Download Building Energy Efficiency

Building Energy Efficiency
Student handbook
Edition
EN1.0 - September 2010
Check IUSES project web site www.iuses.eu for updated versions.
Disclaimer
This project has been funded with support from the European Commission.
This publication reflects the views only of the author and the Commission cannot be held responsible for any
use which may be made of the information contained therein.
Authors:
Sergio García Beltrán (CIRCE), Lucie Kochova (Enviros s.r.o.), Giuseppe Pugliese (CIRCE),
Petr Sopoliga (Enviros s.r.o.)
Layout
Fabio Tomasi (AREA Science Park)
About this handbook and IUSES
This handbook has been developed in the frame of the IUSES –Intelligent Use of Energy at
School Project funded by the European Commission - Intelligent Energy Europe Programme.
The partners of the project are : AREA Science Park (Italy) CERTH (Greece), CIRCE (Spain),
Clean Technology Centre - Cork Institute of Technology (Ireland), Enviros s.r.o. (Czech Republic), IVAM UvA (Netherlands), Jelgava Adult Education Centre (Latvia), Prioriterre
(France), S.C. IPA S.A. (Rumania) Science Centre Immaginario Scientifico (Italy), Slovenski
E-forum (Slovenia), Stenum GmbH (Austria), University “Politehnica” of Bucharest
(Rumania), University of Leoben (Austria), University of Ruse (Bulgaria)
Copyright notes
This book can be freely copied and distributed, under the condition to always include the present copyright notes also in case of partial use. Teachers, trainers and any other user or distributor should always quote the authors, the IUSES project and the Intelligent Energy Europe
Programme.
The book can be also freely translated into other languages. Translators should include the present copyright notes and send the translated text to project coordinator ([email protected])
that will publish it on the IUSES project web site to be freely distributed.
I
Key to symbols
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term, explaining what it means.
Notes: this shows that something is important, a
tip or a vital piece of information. Watch out for
these!
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each chapter and they explain what you will learn
in that chapter.
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have learned.
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came from.
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real situation.
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points) of what you have covered, usually at the
end of a chapter
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to think about a question, especially at the end of
chapters
Level 2: this marks an in-depth section
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HANDBOOK ON BUILDING
Energy Efficiency & Renewable Energies
INDEX
1.
INTRODUCTION............................................................................................................................... 3
1.1.
BUILDING CONCEPT .................................................................................................................... 3
1.2.
BUILDINGS TYPOLOGY ................................................................................................................ 3
2. BUILDING STRUCTURES ............................................................................................................... 7
2.1.
CONCEPT: A BUILDING IS LIKE A BREATH BOX ............................................................................ 7
2.2.
ENVELOPE OF THE BUILDING ...................................................................................................... 9
2.2.1.
Insulation and building materials ...................................................................................... 10
2.2.1.1.
2.2.2.
Reforming with thermal insulation: General examples ........................................................... 12
Windows, glazed surfaces and doors ................................................................................. 12
2.2.2.1.
Windows rating ....................................................................................................................... 13
2.3.
BIOCLIMATIC BUILDING DESIGN ................................................................................................ 14
2.3.1.
Passive solar elements ....................................................................................................... 16
2.4.
TIPS AND HINTS FOR BETTER BUILDING USE .............................................................................. 18
2.5.
EXERCISE/QUESTIONS ............................................................................................................... 19
3. CLIMATIZATION ........................................................................................................................... 23
3.1.
HEATING .................................................................................................................................. 23
3.1.1.
Internal microclimate and comfort..................................................................................... 23
3.1.2.
Heating systems.................................................................................................................. 25
3.1.3.
Type of heat carrier............................................................................................................ 25
3.1.3.1
3.1.3.2
3.1.4.
Hot water..................................................................................................................................... 25
Air heating................................................................................................................................... 25
Energy sources ................................................................................................................... 25
3.1.4.1
3.1.4.2
3.1.5.
Fossil fuels................................................................................................................................... 25
Electric energy ............................................................................................................................ 26
Renewable sources ............................................................................................................. 26
3.1.5.1.
3.1.5.2.
Biomass ................................................................................................................................... 26
Heat pumps ............................................................................................................................. 27
3.1.6.
Solar energy ....................................................................................................................... 29
3.1.7.
Heating elements................................................................................................................ 31
3.2.
COOLING – AIR CONDITIONING ................................................................................................. 33
3.2.1.
Introduction........................................................................................................................ 33
3.2.2.
How does an air conditioner work? ................................................................................... 35
3.2.3.
Energy Label ...................................................................................................................... 36
3.2.4.
Different air-conditioning system options.......................................................................... 36
3.2.5.
Tips and hits on how to use an air conditioner .................................................................. 37
3.3.
EXERCISE/QUESTIONS ............................................................................................................... 39
4. DOMESTIC HOT WATER PREPARATION.................................................................................. 41
4.1.
TYPES OF WATER HEATING APPLIANCES ..................................................................................... 41
4.1.1.
Electrical storage appliances............................................................................................. 42
4.1.2.
Electrical instantaneous appliances................................................................................... 42
4.1.3.
Gas direct instantaneous appliances.................................................................................. 42
4.1.4.
Gas direct storage appliances............................................................................................ 42
4.1.5.
Gas indirect storage appliances......................................................................................... 42
4.1.6.
Other possibilities .............................................................................................................. 42
4.2.
TIPS AND HINTS HOW TO SPARE WATER AND ENERGY ................................................................. 42
4.3.
SOLAR WATER HEATERS ............................................................................................................. 44
4.4.
EXERCISE/QUESTIONS ............................................................................................................... 44
5. LIGHTNING..................................................................................................................................... 46
5.1.
DAYLIGHT................................................................................................................................. 47
5.2.
ARTIFICIAL LIGHTING................................................................................................................ 47
5.2.1.
Sources of light................................................................................................................... 48
5.2.2.
Lamps................................................................................................................................. 49
5.2.3.
Energy consumption........................................................................................................... 49
5.3.
EXERCISE/QUESTIONS ............................................................................................................... 50
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6.
ELECTRIC APPLIANCES AND ELECTRONIC DEVICES (AND SOLAR PV) ......................... 52
6.1.
OVERVIEW ................................................................................................................................ 52
6.1.1.
General tips on how to save energy ................................................................................... 56
6.2.
ELECTRIC APPLIANCES .............................................................................................................. 56
6.2.1.
Refrigerators/ Fridges: ...................................................................................................... 56
6.2.2.
Washing machines: ............................................................................................................ 58
6.2.3.
Dishwashers....................................................................................................................... 58
6.2.4
Ovens ................................................................................................................................. 59
6.2.5
Small home appliances....................................................................................................... 59
6.2.6
Home electronic equipment – Entertainment and home office devices: ............................ 60
6.3.
EXERCISE/QUESTIONS............................................................................................................... 62
6.4.
PHOTOVOLTAIC ENERGY ........................................................................................................... 67
6.4.1
Solar energy ....................................................................................................................... 67
6.4.2
The process of turning sunlight into electricity.................................................................. 68
6.4.3
Photovoltaic applications .................................................................................................. 70
6.4.4
How much electricity can a PV system produce? .............................................................. 71
6.5.
EXERCISE/QUESTIONS............................................................................................................... 74
7. EXERCISE - MONITORING ENERGY CONSUMPTION - HOME/SCHOOL FACILITIES ENERGY AUDIT .......................................................................................................................................................... 77
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1 Introduction
Learning Objective: In this Chapter you will learn:

What is building

What are the types of buildings
1.1 Building concept
Definition: Building is a man-made construction used for supporting or sheltering
any use or continuous occupancy. It is fully enclosed by external envelope (that
means external walls, roof and floor) which creates its internal microclimate.
Buildings come in a wide amount of shapes and functions, and have been adapted throughout
history for a wide number of factors, from building materials available, to weather conditions, to
land prices, ground conditions, specific uses and aesthetic reasons.
Buildings serve several needs of society - primarily as shelter from weather and as general living
space, to provide privacy, to store belongings and to comfortably live and work.
A building as a shelter represents a physical division of the human habitat into the inside (a place
of comfort and safety) and the outside (a place that at times may be harsh and harmful). The first
shelter on Earth constructed by a relatively close ancestor to humans is believed to be built
500,000 years ago by an early ancestor of humans, Homo erectus.
To create required internal microclimate is very energy demanding. So, building construction
and operation have an enormous direct and indirect impact on the environment. Buildings not
only use resources such as energy and raw materials, they also generate waste and potentially
harmful atmospheric emissions. As economy and population continue to expand, designers and
builders face a unique challenge to meet demands for new and renovated facilities that are accessible, secure, healthy, and productive while minimizing their impact on the environment.
Recent answers to this challenge call for an integrated, synergistic approach that considers all
phases of the facility life cycle. This "sustainable" approach supports an increased commitment
to environmental stewardship and conservation, and results in an optimal balance of cost, environmental, societal, and human benefits while meeting the mission and function of the intended
facility or infrastructure.
The main objectives of sustainable design are to avoid resource depletion of energy, water, and
raw materials; prevent environmental degradation caused by facilities and infrastructure throughout their life cycle; and create built environments that are liveable, comfortable, safe, and productive.
1.2 Buildings typology
To differentiate buildings in the usage of this book from other buildings and other structures that
are not intended for continuous human occupancy, the latter are called nonbuilding structures or
simply structures.
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Buildings can be sort by purpose for which they were built:
1) Residential building – apartment building, detached/semi-detached dwelling, row house, cottage, castle, yurt, igloo, mansion, condominium, dormitory
taken by Michael Gardner
2) Educational and cultural buildings – school, college, university, gymnasium, library, museum, art gallery, theatre, concert hall, opera house,
3) Commercial buildings – bank, office building, hotel, restaurant, market, shop, shopping mall,
store, warehouse
4) Government buildings – city hall, consulate, courthouse, parliament, police station, post office, fire station
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5) Industrial buildings – brewery, factory, foundry, mining, power plant, mill
6) Medical building – hospital, policlinic, surgery
7) Agricultural buildings – for example: barn, chicken coop, greenhouse, silo, grainery, stable,
sty, mills
Photo by Lars Lentz
8) Military building – barracks, bunker, citadel, fort, fortification
9) Parking and storage – garage, warehouse, hangar
10) Religious buildings – church, cathedral, chapel, mosque, monastery, synagogue, temple
11) Buildings for sports – sport stadium, pool, gymnasium, court
So there is a big variety of building and also there is a big variety of requirements for these
buildings. All these types of buildings have to create suitable indoor microclimate for purpose
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for which they were built. The requirements are different for all types of buildings, for example
in the warehouse you need lower indoor temperature and much lower humidity than in the indoor swimming pool.
Web links
http://en.wikipedia.org/wiki/Building
http://www.learn.londonmet.ac.uk/packages/clear/thermal/buildings/configuration/
building_orientation.html
http://lonicera.cz/awadukt_thermo/
http://www.vsekolembydleni.cz/clanek.php?id=166
http://www.passivehouse.co.uk/
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2 Building structures
Learning Objective: In this Chapter you will learn:

The important role of building envelope and how energy can be wasted
(including “heat transfer fundamentals”)

An overview of the most common building and insulation materials

Basic concepts of the bioclimatic building design
2.1 Concept: A building is like a breathing box
A building could be seen to be like a box, protecting its contents from climatic conditions, such
as outdoor temperatures, wind, rain, etc.
Indoor comfort, apart from being a subjective matter, depends mainly on two factors: indoor
temperature and humidity. It is obvious that the least comfort is achieved when high temperature
and high humidity works together.
The skin of the building, named the envelope, works like an exchanger with the external climate
conditions, gaining heat from exposure to solar rays and releasing heat towards the outside (due
to ventilation and an inadequate envelope).
The envelope, apart from having the task of wrapping and defending the building, should allow it
to breath, in order to avoid indoor humidity and reach a proper balance between heat gains and
losses*.
Fig.1 Energy balance of a building
This special photo (fig. 2, an infrared picture taken by a thermographic camera*) shows the thermal condition of the building, with the clearer areas (yellow) being the warmer parts, while the
darker (red/blue) ones are the colder areas. It shows the clearest points where heat is escaping.
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In this picture, for example, the wall face has got a thermal gradient (a temperature) of 6.1 ºC at
the thermal point of the floor framework (Sp2 = 6.2ºC). It is 1.1ºC at the wall (Sp1).
Fig.2 Thermographic picture of building
As is shown in the picture, heat is escaping through the windows and because of the thermal
bridges caused by the blind box and the floors.
Fig.3 Thermographic picture of building
Why does it occur?
Definition: That is a physical phenomenon
well known as “Heat Transfer”. According
to this, “Heat always flows from a warmer
to a cooler space”.
It means that in winter, the heat moves directly from all
heated living spaces to the outdoors and to adjacent unheated attics, garages, and basements – wherever there is a
difference in temperature. During the summer, heat moves
from the outdoors to the house interior (when the outside
temperature is higher!).
To maintain comfort, the heat lost in the winter must be
replaced by the heating system, while the heat gained in
the summer may be removed by an air conditioner. That
means a large amount of energy is wasted in most build- Fig.3 Difference of Temperature and heat
ings. In Europe, 70% of the average energy household contransfer
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sumption goes to keeping homes at a comfortable temperature. Typically, natural gas and electricity are used for heating systems, and electricity for almost all cooling systems.
The heat demand for heating the house in the cold season is the major energy-consuming service.
If the heat demand is reduced by means of insulation, heat recovery, superwindows, passive solar
gains and other measures, the heating system can be simplified step by step, and the energy requirement for heating is reduced, as well as the supplier bill and CO2 emissions.
BOX Concept
Heat transfer fundamentals
Note: Heat is always transferred from a warmer to a colder area by three mechanisms:
Fig.4 Heat transfer

Conduction occurs in a solid material when its molecules are at different temperatures. The
hotter molecules transmit energy (heat) to the cold side of the material. For example, a
spoon placed into a hot cup of coffee conducts heat through its handle and into the hand
that grasps it. In buildings, conduction occurs primarily through walls and windows.

Convection is the transfer of energy by the movement of fluids and gases. Warm air rises
and is replaced by colder air drawn in from outside. In multi-storey buildings* with inadequate internal partitions, this can create powerful and wasteful draughts.

Radiation is where the energy is transported by electromagnetic waves*. Unlike the other
mechanisms, radiation requires no intervening medium to propagate. Radiation into buildings occurs mainly through glass windows and doors, but if walls are not well insulated,
radiation falling outside may heat the inside by conduction.
2.2 Envelope of the building
Most of the building energy loss is due to an inadequate envelope, which is composed of the
walls, floors, roof, doors, and windows. The next picture shows from where the heat transfer
typically acts, e.g., external walls and adjacent unheated spaces.
Note: Proper component and insulation materials allow a decrease in the heating or
cooling needed by providing an effective resistance to the flow of heat, or said more
simply, by creating a better conservation of the inside temperature.
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In addition, the colour of the external walls is important, due to their characteristic of reflecting
or absorbing the light of the sun. White and lighter colours act as reflectors, while black and dark
tones are sun absorbers.
Fig.5 Energy looses in a conventional building
2.2.1 Insulation and building materials
Definition: Insulation means all materials with a high resistance to heat flow.
Some commonly used materials for home insulation can be classified according to type:

Vegetable: cork, wood fibre, flax, straw, etc.

Mineral: fibreglass, mineral-wool, expanded clay, metal carbides,
foamed glass, etc.

Synthetic materials: expanded polystyrene, polyurethane and phenolic foams, PVC, etc.
Furthermore, insulation materials are available in a variety of forms. Apart from rigid insulation,
there are: blankets, in the form of mats or rolls, blown loose fibres, foam and spray insulation,
etc.
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They can be used together, thus increasing insulation property, but this requires professional installation and a proper mix.
Good insulation can reduce the heat transfer through walls, roofs, windows, etc., giving the following benefits:




Saves energy because it reduces energy losses during
cold days and allows lower refrigeration loads and temperatures during hot summer days.

Increases comfort by eliminating the “cold wall” effect*
produced in exterior walls and windows (the temperature
difference between the wall surface and the room should
be no greater than 4°C).
Reduces the risk of condensation* which may cause damage to building insulation and
structural materials, discolouration and unhealthy living conditions. The risk of condensation increases with lower ambient temperatures.
Avoids sudden temperature changes, protecting the building from cracks and thermal expansions.
Improves the building’s acoustics.
Insulation material is usually rated in terms of thermal resistance (indicated with an R-value),
which indicates the resistance of material to heat flow (see paragraph 2.2.1.2). The higher its resistance is, the greater the insulating effectiveness is.
Of course, the thermal insulation property depends on the type of material, its thickness, and its
density.
As an example, look at the comparison between 10 cm of thermal insulation and other building
materials.
Graph 1. Material comparison
Note: In winter, each square metre of uninsulated wall loses the equivalent energy of 3
to 6 litres of oil (referring to the oil which is theoretically consumed for heating the
space without insulation). With good insulation, these losses are reduced to one-sixth.
Doubling the insulation thickness of a blank wall from 45mm to 90mm can save about
30% of the energy1.
1 The energy standard of a building is commonly measured by the energy consumed for heating and cooling (kWh)
per each square metre of building surface (m2) during one year. Thus, when we speak about energy losses or savings due to insulation, we are referring to that energy (expressed by kWh or oil equivalent) which would be consumed or saved for heating and cooling.
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For any building more than 20 years old or insufficiently insulated, a retrofit is advisable for improving its insulation, by which a 50% energy savings is easily achieved for heating and cooling.
In addiction to insulation, careful selection of construction materials is the key to achieving high
comfort levels at a low cost, although it is more suited to the new building stage, or when important renovations are needed.
For example, a hollow ceramic brick has very good insulating properties (or high thermal resistance), and other materials like thermal clay have an even better performance.
Fig.6 Example of a hollow brick with excellent insulating properties
Fig.7 Examples of clay bricks
These bricks have an internal structure of air chambers, helping to achieve good thermal and
acoustic insulation.
In summary, in addition to construction materials, it is important to use insulation-layered material in order to achieve better energy saving results and comfort.
2.2.1.1.
Reforming with thermal insulation: General examples
1. Insulation of facade (walls and windows):
By installing thermal insulation material on external or internal walls, or injecting it inside the
wall, and replacing glass and windows with more efficient ones.
2. Insulation of roof, floor and ceiling:
By installing thermal insulation material between tie-beam,* wall,* with tile* adhered onto insulation material, etc., and by insulating ceilings which are in contact with living spaces and roofs
in contact with no living spaces.
3. Insulation of plumbing system:
By installing thermal insulation material around water pipes in order to reduce heat loss in the
transport of hot water.
2.2.2 Windows, glazed surfaces and doors
Note: These are the weakest parts of the building envelope, responsible, on average, of
one-third of a home’s heat loss in winter and cooling loss in summer.
This is due to air leakages, infiltrations and thermal bridges* along the frame of the components,
and is also due to the heat transfer through the component materials. Common windows usually
come with a low resistance to heat flow, which is inefficient.
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Windows and glazed surfaces, which cover a relevant part of a building surface,
as well as working like the other envelope parts to avoid heat loss, play another
important role: they provide natural daylight and, thanks to sunlight, allow heat
gains for indoor space (mainly in cool countries or cool seasons).
Note: Similarly, external doors are responsible, on average, for
10% of a home’s heat loss.
They usually need to be insulated and sealed, mainly at the bottom with weather-stripping* or
insulating rope to prevent air leaks. Or, if the doors are quite old, it would be good to change
them for new ones made of some good thermal insulation material (wood, double-layered aluminium filled with insulation foam or blanket, etc.).
For this, there are two crucial main steps:

The proper shaping and correct positioning of windows and glazed surfaces;

Checking for energy-efficient windows (which provide a great resistance to heat flow).
1.
Large windows should be positioned on the south side, in order to allow the winter sun to warm internal spaces. Conversely, during the
summer, when the purpose is to keep out the hot summer sun, some
sort of shading device should be used, indeed, by putting up a proper
eave or veranda over the window. Conversely, windows located on
the cold north side of the house should be kept to a smaller size, in
order to avoid the cold from the north entering.
2.
Several efficiency degrees of windows are available, mostly depending on frame material and glass characteristics. For instance, a window with an aluminium or iron frame permits a great amount of heat
flow (low thermal resistance), whilst a wood frame is better since it is
an insulating material. Equally, systems with double-glazing or a double window cut heat loss by almost 50% in comparison with single
glazing, as well as reducing air leaks, condensation of moisture and
frost formation.
2.2.2.1.
Windows rating
Windows are rated with the heat-transfer coefficient U-value. Remember that the U is the inverse
value of R (thermal resistance) and the lower the U-value, the better the energy efficiency of the
window.
Note: Double-glazed windows have up to 75% lower U-values
than single-glazed units. The most efficient double-glazed windows allow about 80% of the sunlight received to enter and have
U-values of approximately 2. Windows with U-values of 1 or
lower are sometimes called “superwindows”. Many of the commercially available high-efficiency windows may include multiple
layers of glazing, low-emissivity (low-e) coatings, inert gas-fill
between glass layers and insulating spacers.
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The following figure shows typical U-values of different types of windows.
Fig.8 Windows Rating: U-values of different types of windows
2.3 Bioclimatic building design
The energy efficient model for building counts more than all the
above technical solutions and design principles and many others, as
it is capable of increasing energy savings, indoor healthiness, helping to reduce the greenhouse emissions from fossil-fuel energy use,
as well as reducing household running
costs.
Furthermore, the energy-efficient concept also includes the elements of the well known the “Bioclimatic
Building Design” to provide a naturally comfortable home all year
round.
Definition: The Bioclimatic Building Design consists of adapting the building to particular weather conditions and getting the greatest comfort with the minimum support
from auxiliary energy sources. The sun is the main energy provider in bioclimatic
design.
It is not a new discipline. Most traditional architecture followed bioclimatic principles when artificial heat and cold sources were expensive and limited.
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Active
systems
Solar collectors
Photovoltaic pannels
.....
Bioclimatic
elements
Passive
systems
Direct solar gain
Thermal walls with air
preheating
Indirect solar gain
Trombe walls
Isolated systems:
Sunspaces and Atria
Mass walls
Collectors and grave fills
Fig.9 Main bioclimatic Active and Passive elements
Definition: Bioclimatic elements are commonly classified as passive and active.

Active solar systems are directed towards solar energy capture by mechanical
and/or electrical systems: solar collectors (for space or water heating) and
photovoltaic panels (for producing electric energy), as dealt with in the next
chapter.

Passive solar design maximizes the benefits from the sun using standard construction features, while operating with little or no mechanical assistance. The
natural movement of heat and air or just making the optimum use of the sun,
for instance in terms of daylight and heat, maintain comfortable temperatures.
Fig.10 Active and passive solar elements in a building.
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2.3.1 Passive solar elements
As the above chart shows, passive solar systems are usually further divided into three main elements, according to the method of gaining solar benefits; they are:



Direct solar gain
Indirect solar gain
Isolated systems
Direct solar-gain systems are basically composed of a southfacing glazing surface that traps the sun’s heat into the space
made by the internal wall and the glazed surface. It is a special wall (called a thermal mass) composed of proper materials able to trap and store solar heat and give it off during the
night. Temperatures of up to 27°C can be reached.
Glazing is usually the most important factor in obtaining energy savings.
In south-facing buildings with glazing surfaces of 60%, savings due to direct solar gain range between 15% and 40%,
depending on the insulating material.
The inconvenience is that the same surface demands 55%
Fig.11 Operating principle of a pasmore air conditioning over the summer. Thus, it is usual to
sive solar surface.
place eaves and trees around the building.
They provide shade in the summer and solar gain in the winter.
Then, facilitating crossed ventilation is a very important factor (even more than thermal insulation) when trying to avoid air conditioning in the summer.
Indirect solar gain uses the same materials and design principles as direct gain systems, but
places the thermal mass (the internal wall) between the sun and the space to be heated.
With indirect solar-gain passive elements, temperatures up to 70°C can be reached (remember
that direct solar-gain elements can reach 27°C). These systems are thus great energy-storing surfaces. The high temperatures are slowly attained and slowly lost being the thermal delay between
six and eight hours. During the summer period, they use eaves to avoid overheating.
These systems affect the global design of the building, so they are recommended for predesigned structures.
Among the several types of indirect solar-gain systems, the most common element is the Trombe
walls.
Fig.12 Operating principle of a Trombe Walls.
Solar radiation is collected and trapped between the large external window and the thermal mass
(the wall) and heats the air in between. The particular element is that such vents are located at the
top and bottom of the wall. The top one allows the heated air to flow into the room, while cooled
air then moves to take its place from vents at the bottom of the wall (remember that warm air re16
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mains higher, due to being lighter than cold air).
The thermal mass (the wall) continues to absorb and store heat to radiate back into the room after
the sun has gone. Dampers can be placed in the vents to prevent warm air from escaping through
them at night.
Isolated systems, such as sunspaces and atria (respectively for dwellings and for larger buildings)
represent additional space with attractive architectural qualities. In certain climates, they can also
offer protection against adverse weather at an acceptable cost.
These systems result from a combination of direct and indirect gain systems. They are made up
of a large glazed surface enclosing a thermal mass (greater than the ones in Trombe walls), located between the exterior wall of the building and the glazed surface. The principle of operation
is similar to Trombe walls.
Fig. 13 Operating principle of atria
What are the benefits?
A new building that is planned and constructed following bioclimatic criteria can become selfsufficient from an energy point of view. However, these are exceptional cases and cannot be applied to most projects.
Note: Any building can obtain energy savings of up to 60% by applying bioclimatic
techniques – without running into extra expense and still keeping the final aesthetic of
the project.
The energy standard of a building is commonly measured by the energy consumed for heating
and cooling (kWh) per square metre of building surface (m²) and usually over a year.
Table 3 shows a comparative example between the consumption of a traditional building and a
bioclimatic one. As seen, savings can be up to 67%.
Tab.3 Consumption of traditional versus bioclimatic building
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Each building, depending on the materials used, should have its own energy demand value To
have an estimation of a building energy demand, and knowing its energy demand per square metre, you need to multiply that value by the habitable surface of the building.
For example, having a surface of 240 m2 (example in note) and an energy demand of 169 kWh/m2 (as shown in the table), we obtain: 240 m2 x 169 kWh/
m2 = 40,560 kWh (being approximately the energy demand of the entire
building).
2.4 Tips and hints for better building use
Building design, its envelope materials, windows and doors used, are decisive in having a comfortable living standard. As the greatest part of building energy consumption is due to heating
and cooling (more than 50%), and considering the long life of a building, attention must be paid
to all those structural issues in order to be really cost effective.
Follow the tips below to increase energy efficiency and to save money.
Envelope and insulation

Good thermal insulation should always be planned during the design process of new or restored buildings.

For existing buildings, modifying the structure to improve insulation is usually difficult
and not always cost effective. However, for older buildings, if you are considering building
work, don't forget that correct thermal insulation can make significant energy and money
savings. Reduce the heat losses by using double panes (for windows) and insulation in the
walls. Energy consumption could be reduced by half (50%).

Remember that dark surfaces absorb more solar radiation.

Make sure of the envelope seal, filling cavities and slits wherever air leakages are found.
Doors and Windows

If you cannot replace older doors and windows, there are several things you can do to
make them more efficient:

Open the curtains and the sunshades in southern windows to allow the sun to pass into the
interior.

Do not use drapes or blinds to cover the windows and glazed faces during winter days, because the windows provide the indoor space with natural daylight, and allow sun heat to
enter (solar gain).

Make sure the door is sealed and have door sweeps at the bottom to prevent air from leaking out. Applying weather-stripping and caulking around doors and windows can significantly reduce air leakage.

Keeping windows and doors closed when heating or cooling systems are operating to avoid
losses.



Bioclimatic Building Design and Systems
Building design and structure elements mostly belong to building construction or largescale reform phase decisions; nonetheless, teenagers should be concerned.
There are three bullet points needed to be learned:
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


acquiring an awareness and knowledge of proper design, materials and use of technologies
could be useful when choosing a home to live in, or simply for giving suggestions to your
parents or school headmasters;
There are small-scale, low-cost repairs, which can be carried out, such as sealing cracks,
adding interior movable shades (such as Venetian blinds), installing ceiling fans, using
plants for shade, etc.
there are non-technical measures, even the simplest of which can have energy benefits for
our buildings without added costs, such as ensuring the rational operation of the building
and its systems, the correct use of windows (for sun penetration during the winter, shading
and night ventilation during the summer), and the rational use of appliances so as not to
place a heat burden on the building (for example, not cooking during the hottest part of the
day).
2.5 Exercise/Questions
1.
What is the direction of the heat transfer?
a)
From warmer to cooler ¨ b) From cooler to warmer ¨
2.
Which colours do you think are the best at absorbing the light from the sun and which at
reflecting them?
....................................................................................................................................................
....................................................
Quote three of the most common insulation materials: ........................ .............................
................................ ..................................
3.
4.
Which of the construction solutions would make the best insulator?
10 cm of thermal insulation ¨ or 20 cm of hollow brick ¨
5.
Can you think of any materials which would not be good insulators?
Why? .......................................................................................................................................
.................................................................
6.
Where do the most losses due to air leaks occur?
....................................................................................................................................................
....................................................
7.
What can be done to stop the drafts?
..................................................................................................................................................
..................................................
8.
Where should larger windows be positioned in a building?
South side ¨ 
North side ¨
9.
What device or system could be used to keep hot sunlight from the windows during the
summer?
...................................................................................................................................................
..................................................
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10.
What kind of window shows the best performance and how much range of U-value should
it have?
..................................................................................................................................................
...................................................
11.
Select whether the following techniques are Solar Active (A) or Passive (P)
Photovoltaic panels
Atria
Indirect solar-gain systems
12.
[ ]
[ ]
[ ]
[ ]
[ ]
[ ]
Try to define “bioclimatic building design” and say what could be considered its main energy source.
...................................................................................................................................................
..................................................
13.
What is the inconvenience of solar passive elements during the summer? And how can this
be easily solved?
....................................................................................................................................................
.................................................
14. Tick the functions of the thermal mass (the internal wall) of a passive solar system:
Heat absorption and storage
¨
Protection against climate adversity
¨
Radiating heat after the sun is gone
¨
Allowing air ventilation
¨
15.
According to the building energy-demand measurement (kWh/m²), and supposing that
your school has a demand of approximate 150 kWh/m² per year:
Get (or estimate) the school’s habitable surface (m²) = ...............
Calculate the global energy demand (kWh) = ................
Glossary
Thermographic camera: also called an infrared camera, is a device that forms an image using
infrared radiation, similar to a common camera that forms an image using visible light. It is able
to reveal temperature variations on the surface of a body.
Heat Gain – an increase in the amount of heat contained in a space, resulting from direct solar
radiation, heat flow through walls, windows, and other building surfaces, and the heat given off
by people, lights, equipment, and other sources.
Heat loss – a decrease in the amount of heat contained in a space, resulting from heat flow
through walls, windows, roof and other building surfaces and from ex-filtration of warm air.
Solar heat gain – heat added to a space due to transmitted and absorbed solar energy.
Multi-storey buildings: buildings composed of different floors.
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Electromagnetic waves: are formed when electric fields couple with magnetic fields, which
propagate through space carrying energy from one place to another.
Cold wall effect: the chilly discomfort experienced by a person in a building as his or her body
radiates heat to the cold surface of an uninsulated wall.
Condensation: is the change of the physical state of aggregation (or simply state) of matter from
a gaseous phase into a liquid phase. For instance, water vapour condenses into liquid after making contact with the surface of a cold bottle.
Balk: one of several parallel sloping beams that support a roof.
Piling stick: a stick or strip of wood used to separate courses in a stack, and thus improve air circulation.
Tile: a thin flat slab of fired clay used for roofing.
Kelvin degree: is a unit measure of temperature and is the same size as the Celsius degree;
hence, the two reference temperatures for Celsius, the freezing point of water (0°C), and the boiling point of water (100°C), correspond to 273.15°K and 373.15°K, respectively.
Expanded polystyrene foam: is a plastic material that has special properties due to its structure.
Composed of individual cells of low-density polystyrene, EPF is extraordinarily light and can
support many times its own weight in water.
Fibreglass: also called glass fibre, is a material made from extremely fine fibres of glass.
Thermal bridge: is created when materials that are poor insulators come into contact, allowing
heat to flow through the path created. The bridging has to be eliminated, and rebuilt with a reduced cross-section or with materials that have better insulating properties, or with an additional
insulating component.
Caulk: a soft, semi-solid material that can be squeezed into non-movable joints and cracks of a
building, thereby reducing the flow of air into and out of the building.
Weather-stripping: material that reduces the rate of air infiltration around doors and windows.
It is applied to the frames to form a seal with the moving parts when they are closed.
Web links
http://www.energysavingcommunity.co.uk/
http://www.proudcities.gr/
http://www.eurima.org/
http://www.energytraining4europe.org/
http://www.need.org/
http://apps1.eere.energy.gov/consumer/your_home/designing_remodeling/index.cfm/
mytopic=10250
http://www.cres.gr/kape/energeia_politis/energeia_politis_bioclimatic_eng.htm
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References
VV. AA.: Guía práctica de la energía para la rehabilitación de edificios. El aislamiento, la mejor solución’ (Practical Guide for the Energy Reform of Buildings. The insulation, the best
solution), Instituto para la Diversificación y Ahorro de la Energía (IDAE), Asociación Nacional
de Industriales de Materiales Aislantes (ANDIMA), 2008.
Key points:
Building design, its envelope materials, windows and doors used, are decisive in
having a comfortable living standard. As the greatest part of building energy consumption is due to heating and cooling (more than 50%), and considering the long
life of a building, attention must be paid to all those issues in order to be really cost
effective.
Good insulation can reduce the heat transfer through walls, roofs, windows, etc.,
giving the following main benefits: Saves energy and increases comfort.
According to “Heat Transfer” principle, heat always flows from a warmer to a
cooler space.
Windows, glazed surfaces and doors are the weakest parts of the building envelope,
responsible, on average, of one-third of a home’s heat loss in winter and cooling loss
in summer.
Any building can obtain energy savings of up to 60% by applying bioclimatic techniques – without running into extra expense and still keeping the final aesthetic of
the project.
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3 Climatization
Learning Objective: In this Chapter you will learn:

What the thermal comfort is and how to achieve it.

Heating systems fundamentals

What renewable energy sources are being used for heating

Cooling systems fundamentals

How to use properly the heating systems and air conditioning and save energy.
3.1 Heating
3.1.1 Internal microclimate and comfort
The key task of the heating is to maintain the thermal comfort in the internal space.
Definition: Thermal comfort is one of the most important factors which provide optimal internal environment for people. It’s a condition when the thermal balance between the man and his surroundings is preserved. It means that the heat which man
produces is taken away from the body.
You can simply change the heat flow from your body by changing clothes (increasing the thermal resistance of the body) or activity (with more activity increase the thermal production of the
body).
Note: The basic criterions connected with thermal comfort are operative temperature
(that is the air temperature influenced by the radiation from surrounding surfaces), humidity and air velocity.
There are recommended values of air temperature for each activity to provide thermal comfort.
However in short-term staying in the space where the required temperature is not, people usually
don’t feel the discomfort, because differences between produced and taken heat are balanced by
internal thermoregulation system. This thermo regulating processes have connection with age,
health condition, nutrition and activity of the person and are influenced by the temperature, humidity and air velocity in the internal environment.
It is proven that thermal comfort has got bigger influence on the subjective comfort feeling and working activity than air pollution or disturbing noise. Some studies proved that person achieves 100 % work
output (soft job) in temperature 22 °C. In 27 °C the output falls to 75
% and in 30 °C the output is only 50 % of the maximum.
The humidity is closely associated with the temperature. In winter the
relative humidity falls to 20 % or lower. So the mucosa membrane of
the respiratory system become dry, the striking power of the organism falls down and harmful substances can get in the respiratory system.
However the thermal comfort depends on many other factors, e.g. the temperature of the surroundings surfaces. These surfaces emit the radiation component of the operative temperature
and can be positive or negative. People are very sensitive on radiation. Even though a person has
a sensation of thermal neutrality, parts of the body may be exposed to conditions that result in
thermal discomfort. This local thermal discomfort can not be removed by raising or lowering the
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temperature of the enclosure. It is necessary to remove the cause of the localised over-heating or
cooling.
Note: Generally, local thermal discomfort
can be grouped under one of the following
four headings:
1. Local convective cooling of the body
caused by draught
2. Cooling or heating of parts of the body
by radiation. This is known as a
radiation asymmetry problem.
3. Cold feet and a warm head at the same
time, caused by large vertical air
temperature differences.
4. Hot or cold feet, caused by uncomfortable floor temperature.
Remember, only when both the local and general thermal comfort parameters have been investigated, the quality of the thermal environment can be judged.
Tab. 1 - Recommendations for winter thermal comfort
Room
Habitable room
Kitchen
Air temperature (°
C)
Intensity of air
changes (h-1)
Air amount
(m3 . h-1)
18-22
3
3 on 1 m2 floor
Gas 3
150
Electricity 3
100
15
Kitchen corner
Bathroom
24
-
60
Bathroom with toilet
24
-
60
Toilet
16
-
25
Lavatory
18
0,5
-
Cloak-room
18
1
-
Pantry
15
1
-
Hall, staircase
10-15
Relative air humidity has to be between 30-60%
Air velocity – in winter max. 0,15 m.s-1; in summer max. 0,25 m.s-1
Note: So the recommended temperature for long-term staying of persons is 19-24 °C.
For small children, elder people and sick or undernourished people the temperature
should be higher – about 23-24 °C.
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3.1.2 Heating systems
There are different types of standard heating systems. We can sort them by the source, place of
the source, type of heat carrier, temperature of the heat carrier, type heating element etc.
Local heating means that the source of the heat (e.g. fireplace) is in the room which should be
heated. Central heating is often used in cold climates to heat private houses and public buildings.
Such a system contains a boiler, furnace, or heat pump to heat water, steam or air, all in a central
location such as a furnace room in a home or a mechanical room in a large building. In big cities
district heating is often used.
3.1.3 Type of heat carrier
Typical heat carrier is hot water or air, but there can be used also other as electricity, steam, etc.
3.1.3.1 Hot water
This system can be low or high temperature. Traditional hot water system with radiators is much
extended in Europe, because this system is optimal for solid buildings with brick or stone walls
and natural ventilation which were the most common in the past. This traditional system is also
optimal for solid fossil fuel sources which are not much flexible.
Note: This system can be applied also in low energy buildings, but there are some differences between traditional system and system for new buildings. The output of radiators is essentially lower, so the system reacts more flexibly on the change of the internal
gains.
3.1.3.2
Air heating
Air heating system of residential buildings is not in contrast to office or industry buildings often
used in Europe. The main reason is the climate conditions, historical development and the connection of the heating system to the construction of the building. The heat carrier in this system
is air. In comparison with water, air has got lower heat capacity so it’s worse heat carrier than
water.
Note: The modern conception of this system is connection of air heating and ventilation. This is usable mainly in the well insulated buildings with low energy demand. In
contrast to circulation system there is controlled fresh air supply which provides the hygienic air interchange.
3.1.4 Energy sources
3.1.4.1 Fossil fuels
Solid fossil fuels, such as hard coal, brown coal, anthracite or coke, were usually used in past.
Note: Heating with solid fossil fuels is one of the main sources of air pollution. Burning
of these fuels generates emission of sulfur, nitrogen and carbon oxides, dust emissions,
emissions of organic and inorganic compounds and others.
In past these sources were hardly controllable and not flexible. Also the combustion efficiency
was low and amount of emissions was high. Modern boilers have got higher efficiency and pro25
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duce less emission. But you should remember that fossil fuels are non-renewable source and
there is limited reserve of the fuels.
Liquid fossil fuels are also popular in some countries. But today’s most used fossil fuel is gas.
Gas has got many advantages in comparison with other fossil fuels. Burning gas instead of solid
fossil fuel emits much less pollutants – emissions of dust and sulfur dioxides (SO2) are almost
insignificant and also amount of carbon oxide (CO) is much lower. The only problem is that
burning gas emits nitrogen oxides (NOx), but nowadays manufacturers lower NOx emissions to
10% of former values. European standards divides heaters in to 5 groups according to amount of
NOx emissions. Gas, like any other carbon fuel, is the source of carbon dioxide (CO2) which is
nowadays considered to be the substance most responsible for greenhouse effect.
3.1.4.2
Electric energy
Electrical heating belongs to most comfortable sort of heating from the view of installation, service, thermal comfort or response rate. It is also available everywhere. But today the price of
electricity rises, so this type of heating is suitable mostly for well insulated buildings where the
energy demand is low. You also shouldn’t forget that mostly fossil fuels are burned to produce
electricity.
3.1.5 Renewable sources
3.1.5.1. Biomass
Definition: Biomass is the organic substance. In the energy context it’s usually wood and wood waste, straw,
grain and other agricultural remains. Biomass may also
include biodegradable wastes (such as dung, sewage etc.)
that can be burnt as fuel.
Basic technologies of the manufacturing are the dry process – combustion, gasification and pyrolysis and wet process – biochemical transformation, such as methane fermentation, ethanol fermentation and production of the bio-hydrogen. To the special group belongs mechanicchemical transformation – oil pressing and its modification, e.g bio-fuel.
Note: Wood or straw are, if they are combusted well, the
second most environmentally friendly fuels. The only pollutants emitted by combustion are nitrogen oxides and
some solid pollutants. The carbon dioxide is consumed by
plant growing, so the no problem with these emissions. The
wood contains almost no sulfur, in straw there is about
0,1% so also these emissions are very low.
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Combustion and gasification
The combustible gases are emitted from dry biomass by high temperature. If the air is present,
the biomass is burning normally, but if the air is not present gas is combusted similarly like other
gas fuels. The output can be easily controlled, emissions are lower and efficiency is higher.
Biomass is very complex fuel, because the part of the gasification is high (wood - 70%, straw 80%). These gases have got other burning temperatures, so very often only a part of fuel is burning. The main condition of the well combustion is high temperature, efficient mixing with air
and enough space in furnace for burning whole fuel.
Fuel value of the wood and other plant fuels varies with type of wood or plant and with humidity. The energy amount in 1 kg of the dry wood is about 5,2 kWh, but in praxis you can dry the
wood completely, the moisture is about 20 % of the weight of the dry wood. So the energy
amount of this wood falls down to 4,3 – 4,5 kWh.
Nowadays biomass is combusted not only in residential building but also in power plants or heating plants. The furnace in the one family house gasificates the fuel first and then burns it. This
system is very well controlled and it is comparable with gas furnaces. Disadvantage is the manipulation with fuel and its storage. Also transport and supply can be problem – depends on the
locality. From technical point of view biomass is not much suitable for small low energy buildings, because there are problems with low output and regulation. Also the protection against low
temperature corrosion should be installed. Very useful is using accumulation and combine it with
preparing domestic hot water.
Heaters in family houses usually burn wood chunks, briquettes, wood chips or wood waste.
Biogas
Biogas rise from organic substances (dump, mulch, sewage) in closed tank without air presence.
The biomass is heated to 37 – 60 °C in biogas facility and the bacteria transform the biomass to
biogas.
Fermentation
The ethanol is created from sugar water, from turnips, grain, corn, fruits or potatoes. Theoretically you can create 0,65 l of 100 % ethanol from 1 kg of sugar. This clean ethanol is very good
fuel for gas-engines.
3.1.5.2.
Heat pumps
Nowadays heat pumps become slowly usual heat source. The increasing price of energy helps expansion of heat pumps to residential
(especially one family) buildings.
Definition: A heat pump is an electric device with
both heating and cooling capabilities. It transforms the
natural low temperature heat from water, soil or air
into heat with higher temperature which can be used
for heating.
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How heat pump works
Note: The major part of the heat pump is the cooling circuit with electrical compressor.
Other parts are two heat exchangers – evaporator and condenser.
The evaporator takes the low potential heat
from the outside environment (air, soil, water), so the outside environment become
cooler, and heat is carried by the compressor
to the condenser. In condenser the heat is
emitted to the environment with higher temperature (heating system, domestic hot water)
and this internal environment becomes
warmer. The heating output of the heat pump
is the sum of the electrical energy of the compressor and low potential energy of outside
environment.
heating  factor 
heating  output
1
electrical  input
Heating factor usually varies between 2,5 to 3,5. It means that from 1 kWh of electrical energy
we can get from 2,5 to 3,5 kWh of thermal energy. In special cases we can get more – about 4-5
kWh. The heat pump is efficient when the thermal difference between environments is high. It
uses 60-70 % of natural energy. The heat pump itself doesn’t produce any emissions.
Sources of low potential energy for heat pumps
1. Water
We can use both underground water and surface water. The
only condition is that it has to be clean, the lowest temperature
has to be over +8 °C, and there has to be enough amount of the
water. When using underground water two wells should be
constructed - one for collection and the other for infiltration.
The used water mustn’t be emitted into a sewage system or
stream, because the ecologically more valuable underground
water would become into less valuable surface water.
2. Geothermal energy
The heat from the soil can be easily
used by the pipe absorber. The heat is
taken indirectly – there has to be a carrier medium between the evaporator
and soil, usually it’s a refrigerant. Absorber is composed from plastic pipeline which is installed vertically in the
wells or horizontally in the surface collector. The output is regulated with the
length of the pipeline.
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3. Air
The external air, which contains the low potential heat, flows
through evaporator. This source is easily accessible, unlimited
and doesn’t influence the external environment, because the heat
taken from the air is put back by heat losses of the envelope. But
with varying of external air temperature the output of the heat
put varies.
3.1.6 Solar energy
Climate change, atmospheric pollution and, in general, the alarming environmental situation,
mainly caused by the continued use of fossil energy sources, are slowly becoming growing concerns and are leading to the development of new alternatives for supplying electricity, wellknown as Renewable Energies.
Note: One of them is solar energy, the source of which is simply the sun; it is available
for free, is inexhaustible and can be used in different ways.
What is Solar Energy?
Every day the sun sends out an enormous amount of energy in the form of radiation. Like others
stars, the sun is a large ball of gases, mostly hydrogen and helium atoms, in a constant combustion process, or said better, in a combining process among those atoms called nuclear fusion.
Simply said, the hydrogen atoms combine or fuse to form helium in the sun’s core under extremely high temperature and pressure conditions. Precisely four hydrogen nuclei fuse to become
a helium atom which contains less matter than the previous four of hydrogen. This loss of matter
is what is emitted into space as radiant energy, the first source of life on the planet earth.
Fig.14 Energy radiations
Only a smart portion of the energy radiated hits the earth, one part in two billon, the remainder
being spread into space. Of that small portion, about 15% of the sun rays are reflected back into
space, another 30% cause water evaporation which is stored in the atmosphere producing rainfall, and finally, solar energy is also absorbed by plants, the land and the oceans, allowing vege29
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table life through the photosynthesis mechanism. Only the rest could be used to supply our energy needs, yet this amount of energy is enormous.
How can we use solar energy?
We have many options for using solar energy at home, school and building in general. The three
main ways are:
1.
Passive heat: it consists of getting use by the heat naturally received from sun. The main
application is in the design of buildings where less additional heating is required (look at
the chapter on building design).
2.
Solar thermal: where we use the sun’s heat to provide hot water for homes or swimming
pools or also heating systems (look at the chapter on water).
3.
Photovoltaic energy (PV): The direct transformation of solar energy into electricity, able to
run appliances and lighting. A photovoltaic system requires daylight – not only direct
sunlight – to generate electricity.
Note: Active systems use various types of solar collectors
and can be additional source
for heating – percentage of
using depends on the geographic latitude, times and intensity of the sunshine. It’s
always system with heat accumulation, mainly to the water
tank but it can be also pool, or
gravel storage, then the accumulated energy is used usually
for heating or mainly for domestic hot water. But a rule
proceeds that longer accumulation means higher costs.
Solar system has to be connected with other heating source (e.g. gas boiler, electrical boiler etc)
in case that there is no or a little sunshine (cloudy, night etc). In summer the heat carrier can be
water, but in the year-long operation the non-freezing liquid has to be used.
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For guaranteeing maximal efficiency of the
system is necessary to find suitable combination of the solar panel, heat accumulator
and the working temperature of heating
system. The regulation of the system is
very important. There are many sensors
connected to main part of the system and
regulating system. When the sensor on the
solar panel discovers that temperature of
the panel exceeds the temperature of the
tank, the regulation switches the pump on
and the heat from panel is carried into the
storage. When temperature in the tank
reaches temperature of the panel, pump is
switched off. So the heat losses are prevented.
3.1.7 Heating elements
Definition:The main task of the heating elements is to put enough heat to the internal
space to create thermal comfort. The quantity
can be regulated by the type, size and way of
installation of the heating element.
Note: The heating elements (radiators or vents)
should be located in the coldest part of the room,
typically next to the windows to minimize condensation and offset the convective air current formed
in the room due to the air next to the window becoming negatively buoyant due to the cold glass
(see picture).
Devices that direct vents away from windows to prevent
"wasted" heat defeat this design intent. Cold air drafts can
contribute significantly to subjectively feeling colder than the
average room temperature. Therefore, it is important to control the air leaks from outside in addition to proper design of
the heating system.
31
Radiator next to the window A – floor convector, B – intensive zone of underfloor heating, C – underfloor heating IUSES — building handbook
On contrary when the element is integrated into the internal surface (e.g. underfloor heating), the
cold air from the window falls down to the floor and creates unpleasant convective flow with
velocity about 0,3 - 0,5 m/s. The floor heating near window should be intensified or floor convector should be installed to deflect the unpleasant flow.
Types of heating elements
1. Radiators
It’s a mistake to think that you can use only underfloor or wall heating in the low temperature heating systems. The modern radiators
can be used also in the low-energy building without any problem
connected with volume of the radiator. However it’s important to
choose carefully the suitable type heating body. Radiator transmits
heat by radiation and convection.
Sectional radiators are composed from several sections and are
manufactured from the different materials – usually from steel
sheets, cast-iron or aluminium. These type
of radiator has got very good hydraulic characteristics. The water content and weight is high so the radiator doesn’t react enough quickly.
That can be a disadvantage in case of using flexible source of heating
and automatic regulation.
Sectional radiators are characterized by the long lifetime - some types
about 80 years without corrosion.
Board radiators belong to the most common radiators. These radiators
are composed from plain or wavy steel boards (from 1 to 3).
Note: Compared to sectional radiators board radiators contains only 1/3 of water, so
they are much more flexible and can be easily regulated by thermostatic valve.
Tubular heating body is mostly installed in the bathroom, toilets or hall.
They consist of several small steel of copper tubes welded together. They
are usually very aesthetical, and are available in many shapes, sizes and colours. It is possible to install it inside the space like the parting wall. This
type of heating element is ideal for drying laundry but hasn’t got enough
high output to heat big room. And also in bathroom it’s recommended to
use it as additional source.
2. Convectors
Convector is a heating element, which transmits heat by convection. It
consists of the exchanger and the case with grating on the upper side.
It can be placed on the
wall, built into plinth or
floor. The inbuilt convector has got small
output so the ventilator
has to be installed to
increase the output.
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3. Underfloor heating
Definition: Underfloor heating is the large-area radiation heating. There are two
types of underfloor heating - hot water or electric.
Using this type of heating element you need lower temperature to maintain the thermal comfort in the interior so low potential source as heat
pump, condensing boilers or solar panels can be used for hot water heating. Electric heating is mainly used as additional element to maintain
higher comfort.
4. Wall heating system
Wall heating system has got the same development as underfloor heating, but is not used so usually. The cost of investments is higher, but it brings some advantages. It creates an ideal climate;
it is flexible in designing and using and brings new possibilities in heating old houses.
External walls emit cold to the room when you use heating system. That turns round with wall
heating system and external wall emit heat to the internal space. So we need low temperature for
heating and the low potential sources can be used. And in contrast to underfloor heating the temperature of the wall is not limited. The construction is similar to underfloor heating.
3.2 Cooling – Air conditioning
3.2.1 Introduction
Air-conditioning systems allow the maintenance of a pleasant temperature in buildings during
the warmer season. It is a relatively recent luxury to choose the desired temperature at which to
keep our homes. In fact, in the last few years, the relevant price drop of those cooling devices has
widely spread their use in more and more residential buildings.
Furthermore, in the great majority of cases, buildings don’t
come with central systems, which would make them more
efficient, while air-conditioning units are installed in single
apartments..
Note: As a consequence, air conditioners are
shooting up the summer utility bills of industries,
hotels, hospitals, institutional buildings, schools,
etc. and, in many warmer European regions, the
household energy consumptions are becoming
greater during summer than winter, due to the extended use of such cooling systems.
Before explaining how an air conditioner works and its typology, the following question needs
reflection.
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What is a comfortable temperature?
Definition: Thermal comfort is very difficult to define because
you need to take into account a range of factors when deciding
what will make people feel comfortable. The most commonly
used indicator of thermal comfort is air temperature, although
other factors, like humidity and air movement, together affect the
thermal comfort feeling.
A comfortable environment is one in which the occupants do not express any
sensation, either cold or hot, because the ambient conditions produce an adequate and sufficient feeling of well-being.
Why define comfort?
An air-conditioning device needs to have a working temperature set, usually from a remote control, above which temperature it starts to cool. Thus, it is advisable to select an appropriate temperature, because if it is too low, the device will be running for too long, but if it is too high the
device will work for only a little time and therefore not be cooling enough.
Often we don’t appropriately consider the necessity of a cooling device or its power and consumption. Thus, defining comfort will allow the selection of the suitable temperature on the thermostat.
What is more comfortable?
The following example clarifies what has been said:
On a summer’s day, the temperature in my town at 15:00
is 38ºC, what is more comfortable?
A) Entering and exiting a building whose interior
temperature is 18ºC?
B) Entering and exiting a building whose interior
temperature is 24ºC?
In option A, the body experiences a sharp jump in temperature of 20ºC, while in option B, this jump is reduced
to 12ºC.
According to the comfort definition, in this case it is
much more comfortable to set the air conditioning to
24ºC.
Note: In summer, the temperature setting of an air conditioner should be such that, entering the building, a feeling of cold is not experienced. Despite the fact that the air conditioning allows you to select temperatures below 18ºC, the operating temperature in
the summer must be between 23ºC and 25ºC.
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And ...What is this for?
To select the suitable air-conditioning temperature gives us four main linked advantages:




Increasing the comfort;
Cutting down the hours of equipment operation, thus consuming less energy;
By consuming less energy, we reduce our electricity bill;
Having temperatures in the house too low is not healthy; it produces a sudden thermal
jump causing the majority of slight summer colds.
3.2.2 How does an air conditioner work?
Definition: The function of any refrigeration or air-conditioning
system is to transport heat from one station to another with a certain amount of work, i.e., electricity consumption.
It is like an exchange where heat is absorbed from inside the
home, getting cooled, and transported to the exterior where is
released.
To do this, the cooling device uses a vehicle substance, well known as “refrigerant”, with suitable physical characteristics. It is a special substance that passes from the fluid to the gas phase
over low temperature conditions. During that phase change , the changed heat is trapped.
A cooling system consists of four basic parts (compressor, condenser, expansion device, and
evaporator), within which the refrigerant fluid is continuously circulated.
The basic system is divided into four steps as is shown in figure 14.
Steps 4–1: The refrigerant passes through the evaporator (situated indoors), where it removes heat from the
warmer space (the inside room), being cooled. This
heat absorption process results in the vaporization of
the refrigerant, which means it passes into the gas
phase (as said above, it passes into the gaseous phase
to trapping heat).
Steps 1–2: The refrigerant leaving the evaporator (in a
vapour low-pressure state) is compressed into a relatively high pressure and temperature by the compressor. It is in the compressor device where electricity is
consumed.
Steps 2–3: Next, the higher pressure and temperature
refrigerant passes through the condenser (situated outdoors), where it condenses due to contact with a cooler
Fig. 14 Basic scheme of a vapourmedium such as the outdoor air, thereby there is a heat
compression refrigeration system
transfer from the refrigerant to the cooler surroundings.
Steps 3–4: Finally, the higher pressure and temperature
refrigerant is reduced in pressure by an expansion valve for delivery to the evaporator.
Obviously, the evaporator device is situated indoors and the condenser outside the building.
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What about their efficiency?
In recent years, concern for the conservation of energy has led manufacturers of air conditioners
to significantly improve their devices to become more energy efficient.
The efficiency of an air conditioner is indicated by the Energy Efficiency Ratio (EER). It defines
“what you get for what you have to put in”, where the useful effect (what we get) is the removal
of heat from the indoor space and what we have to “put in” is the electricity consumption by the
compressor.
The higher the EER is, the more efficient the air conditioner is.
Energy
Efficiency Scale
EER
A
3.20 < EER
B
3.20 ≥ EER > 3.00
C
3.00 ≥ EER > 2.80
D
2.80 ≥ EER > 2.60
E
2.60 ≥ EER > 2.40
F
2.40 ≥ EER > 2.20
G
2.20 ≥ EER
EER 
Heat _ Re moved
Energy _ required
Table 4 Energy efficiency scale
Therefore, the older air conditioners can have an EER of about 2.2, while the new ones can have
a value of approximately 3.5. It means that, comparing these two devices, as the amount of heat
to be evacuated is the same, the device with less EER consumes 60% more energy than the highest EER in performing the same function (3.5/2.2 = 1.60).
3.2.3 Energy Label
With the objective of saving energy to reduce CO² emissions, the European
Union regulates the energy labelling of all air conditioners.
The label for energy efficiency reports on the energy
consumption of air conditioners. They are graded on
a scale from A–G, where A represents the best
equipment that is widely available and G the worst
(see figure).
The energy label will also show the estimated annual
energy consumption in kWh.
Equipment with a higher rating may cost a little
more initially, but G-rated equipment will use 50%
more electricity under normal operating conditions
compared to A-rated units.
3.2.4 Different air-conditioning system options
First of all, before acquiring an air-conditioning system, you need to make sure that you really
need it. Air conditioners are quite expensive when compared to fans and, most importantly, they
consume large amounts of electricity.
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Are you sure you cannot reach a comfort level using an inexpensive fan?
Note: In most cases, a fan will produce the same comfort feeling as an air conditioner.
They lead to temperature feelings of 3°C to 5°C lower than the actual temperature and
have a lower electricity consumption (usually less than 10% of air-conditioner electrical
consumption).
If you have finally decided that you need an air conditioner, choose the type of
system that matches your needs. Shown below are the main air-conditioning system options.
Condenser
Evaporator
Room Air Conditioners
They are used to cool single rooms rather than an entire
building. They are less expensive to operate than central
units, but their efficiency is generally lower.
The most commonly used are
Packaged system
“Split System” ones (as in figSplit system
ure), meaning that the coil
(Evaporator) is located indoors
and the condenser, outdoors. Both units are connected to each another
through a conduit, through which cooling fluid circulates.
When the evaporator and the condenser are both located in the same
case, the system is called a “packaged system” or “combos”.
Central Air Conditioners
Central air conditioners use supply-and-return ducts distributed throughout the building, through
which the cooled air and the later warmer air circulate.
Most central air conditioners are split systems (see above).
Heat Pumps
A heat pump can serve as a heater and as an air conditioner. In the winter, a heat pump draws
heat from the outdoor air and circulates it through ducts into the building.
During the summer, it reverses the process and draws heat from the interior air and releases it
outdoors. These systems can make significant energy savings, as they work both as heaters and
as air conditioners.
Note: During the summer, air conditioning can account for 50% or more of your total
electric bill.
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3.2.5 Tips and hints on how to use an air conditioner
Follow the tips below to increase energy efficiency and save money.

Avoid using air conditioners when possible:

In most cases, a fan will produce the same comfort feeling as an air conditioner.

Avoid unnecessary heat flows, such as excessive lighting, hot equipment, etc. Switch
off when unused.

Eaves and awnings are good tools that avoid the entry of sunlight during the summer
(see the chapter on windows below).

Properly sized and correctly use of your air conditioner:
Surface to cool (m2)
Cooling Power (KW)
9 – 15
15 - 20
20 - 25
25 - 30
30 - 35
35 – 40
40 – 50
50 – 60
1.5
1.8
2.1
2.4
2.7
3
3.6
4.2
Table 5. Guidance for dimensioning
N.B. Indicative values such as construction materials, orientation and design of the building significantly influence cooling needs. For example, if the room to cool is very sunny or if it is an
attic, we should increase the table cooling power values by 15%. If there are heat-source devices,
as in the kitchen, power will be increased by 1 kW.






Set an acceptable level of comfort (between 23ºC and 25ºC, the second one being the
best level) and install control devices (thermostats) to regulate the air-conditioning
system according to the required temperature. With each degree below the comfort
temperature, you are wasting 8% more energy.
Keep doors and windows closed when the air conditioner is running.
Good insulation is very important in avoiding cold leaks (follow the same advice
given in the Heating systems section and look at the Insulation section).
Make sure the cold flow is well distributed throughout the space, avoiding areas with
too cold or too hot air streams (near windows, doors, etc). If your air conditioner has
adjustable louvres, adjust them towards the ceiling, since cool air falls.
Look carefully at the energy rating of the new air conditioner, where A represents
the best equipment and G the worst.
Correct installation and proper maintenance of your equipment:


Place the condensing unit outside and in a well-ventilated area away from solar radiation.
In room air conditioners, place the system in a window or wall area near the centre
of the room and on the shadiest side of the house.
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
Clean and check your air conditioner every few months. Dirty filters and coils can
block the normal air flow and impair the heat-absorbing capacity of the evaporator,
reducing the efficiency of the system. Savings can range between 3% and 10%.
3.3 Exercise/Questions
1.
What can create local discomfort?
………………………………………………………………………………………
2.
What heat carrier is often used in heating system?
………………………………………………………………………………………
3.
Explain how does the heat pump work?
……………………………………………………………………………………….
4.
Why should the heating factor of the heat pump be higher than 1?
……………………………………………………………………………………….
5 Name components of the solar heating system:
……………………………………………………………………………………….
6
7
What are the three main factors affecting thermal comfort?
– ........................ – ........................... – ............................
What should the operating air-conditioner temperature be set at in the summer season in
order to feel comfortable and to avoid a sudden thermal jump? .....................
8
In an air-conditioning system, in what device/part is electricity consumed? (Tick the
correct one)
Compressor
 – Evaporator

Condenser

Web links
http://www.rerc-vt.org/solarbasics.htm
http://www.price-hvac.com/media/trainingModule.aspx
http://www.idae.es/
References
Greg Pahl: Natural Home Heating: The Complete Guide to Renewable Energy Options, Chelsea
Green Publishing, 2003
ASHRAE, Fundamentals Handbook (SI), GA, ASHRAE, 2001, Atlanta.
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Moran, M. J. and H. N. Shapiro, Fundamentals of Engineering Thermodynamics: SI version,
John Wiley & Sons, Inc., 2006.
VV. A. A.: Guía Práctica de la Energía. Consumo Eficiente y Responsable (Practical Guide for
Energy: Efficient and Responsible Consumption), Instituto para la Diversificación y Ahorro de la
Energía (IDAE), 2007, Madrid.
Key points:

Thermal comfort is one of the most important factors which provide optimal
internal environment for people.

The best way how to provide thermal comfort without increasing energy consumption is to achieve just the recommendations - temperature especially - not
overheating or overcooling

There are several possibilities and combinations of heat source and heating elements. It is important to choose optimal combination and proper regulation.

There is a good possibility to use effectively renewable sources - solar, biomass, heat pumps

Air conditioners are shooting up the summer energy bills of industries, hotels,
hospitals, institutional buildings, schools, etc. of many warmer European regions.

The function of any refrigeration or air-conditioning system is to transport heat
from one station to another with a certain amount of work, i.e., electricity consumption. It is like an exchanger where heat is absorbed from inside the home,
getting cooled, and transported to the exterior where is released.

Air conditioner operating temperature in the summer must be between 23ºC
and 25ºC (the second one being the best level). With each degree below the
comfort temperature, you are wasting 8% more energy.

In most cases, a fan will produce the same comfort feeling as an air conditioner. They lead to temperature feelings of 3 °C to 5 °C lower than the actual
temperature and have a lower electricity consumption.
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4 Domestic hot water preparation
Domestic hot water preparation is usually the second highest amount in the heat consumption of
the house. Consumption depends on the user’s habits and differs in every country and every
household.
Note: Is said that minimum consumption is about 40 litres per one person and day what
is about 2 kWh. Average consumption is about 3,4 – 4 kWh per person and day (this
number includes the losses in the piping). .
In houses with central heating system the same source is used for heating and hot water preparation. In houses with local heating system electricity is used most.
Note: To avoid heat losses the pipeline should be as short as possible and well insulated. Temperature should be about 45-60 °C.
During the heating period domestic hot water is usually prepared together with heating. In summer the water preparation should be separated, because you don’t use whole input of the heater.
Especially, efficiency of an old heater can drop to 40 %, modern heaters can switch into the summer mode, so the efficiency can be 80 % or higher.
Table 1. How much potable water we need/consume?
Washing hands
Daily body care
Dishes (1 person)
Taking a shower
Taking a bath
Washing hands
3-6l
9 - 12 l
4-7l
30 - 50 l
150 - 180 l
3-6l
37 °
37 °
60 °
37 °
27 °
37 °
0,1 - 0,2 kWh
0,3 - 0,4 kWh
0,3 - 0,5 kWh
1,0 - 1,7 kWh
5,0 - 6,0 kWh
0,1 - 0,2 kWh
4.1 Types of water heating appliances
There several systems to prepare hot water – instantaneous water heaters or storage system, direct or indirect heating. And all can be sorted by the source of energy. Direct heating means that
the water is in contact with the source of heating (electricity, flame etc). Indirect means that water for consumption is heated through heat exchanger.
Storage system is the oldest system of preparation potable water. The inequality of the consumption and production is covered by the storage. When the uncontrollable heater for solid fuel is
used, the storage is even required. The calculation of the proper size of the storage depends on
the time of heating the water, and then using use this time you calculate input of the storage. This
type of boiler has got low take-off for long time. The disadvantage is that the heat loss can be
quite high (new types have got the loss printed on the energy label).
When you use instantaneous heater, the water flows throw the heat transfer surface and get
warmer. Instantaneous heaters are not suitable for places where the consumption is often and it’s
in small amounts (e.g. washing hands). The temperature changes with the outflow, so it can be
problem sometimes. This type of heaters has got on contrary high take-off for shot time. But this
type is quite sensitive to earthy water.
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4.1.1 Electrical storage appliances
Electrical heating is usually the direct heating. Water in this type of appliance is usually heated at
night, when the electricity is cheaper. So the advantage is the lower price of electrical energy and
also low input of the appliance. The heating spiral connected to the heating system can be installed in the storage, so in winter you can heat water by cheater heat from the heater. This type
of appliance is called combination (or ‘combi’) boiler. The disadvantage is limited volume of
water you can heat. When you consume whole storage, you have to wait quite long (sometime to
the next day) for next hot water.
4.1.2 Electrical instantaneous appliances
This type is usually placed under the sink. When you use this type of appliance the hot water is
available every time, but on contrary it brings disadvantage is that the installed input of this appliance is quite high. So you need better circuit breaker and that means higher costs and bills.
4.1.3 Gas direct instantaneous appliances
This type of appliance was common in the past. Today the gas storage appliances are usually
used. Main advantage of this type is simple construction and operation, and also small proportions. On contrary the efficiency is low and temperature varies with the flow.
4.1.4 Gas direct storage appliances
This type eliminates disadvantage of the instantaneous heater. Input of the burner can be lower,
temperature doesn’t depend on the flow and efficiency is higher even if you take out only small
amount of water. But it’s bigger and price is higher. In comparison with electrical heater, gas
heater can operate during whole day; the input is higher, so the size can be smaller. This water
heater can also be connected with the heater or there are a lot of heaters with integrated storage
in the market.
4.1.5 Gas indirect storage appliances
These are connected to the gas heater and heat
the water through the exchanger installed inside
the tank. This solution is suitable when you use
other source in addition to the gas heater.
4.1.6 Other possibilities
The storage with heat exchanger is the universal
system of water heating and can be used with
any other source of energy, e.g. fossil fuels, biomass, wood, solar energy, heat pump etc. Also
geothermal energy can be used. Counter-flow exchangers are used recently, but mostly to accumulate the energy into the water is preferable. With solar system or heat pump accumulation is
necessary.
4.2 Tips and hints on how to spare water and energy
It’s not pleasant to pay bills especially when the price rises constantly. So it’s better to spare energy and water. In fact you spare two times – water and also energy needed for the heating.
Preparation potable water presents about 25 % of the energy consumption.
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Note: First step is to prevent all leakages of the hot water. Dripping 10 drops in one
minute represents 40 litres per week.
Next step is to lower the consumption. There are a lot of possibilities. Take a shower or bath?
Cheaper is taking a short shower because only one third of water is consumed in comparison
with taking a bath. Also using the showerhead for washing hands or dishes can spare water, because the water is enriched by air and so the higher flow is made. With economical showerhead
in the shower you can spare other 30-35 % of potable water. Using single handle faucets which
reduce time of regulating temperature can spare almost 20 % of energy needed to heat the water.
If you comply with all these principles you can spare 30 – 40 % of energy needed to heat the water, that’s about 7 – 10 % of single family household consumption of energy. And that’s not a
small amount.
So look at possible spares in detail:
Mixing
A great loss of water and energy presents time of mixing water from the tap. A huge amount of
water flows off without any use till you mix water with suitable temperature. So there is one simple trick: open the hot water first and wait till it flows. Then open the cold one which has temperature about 20 °C because it’s warmed in the pipeline and mix it. After a while cold water
from the source (10 °C) flows and brings down the temperature. If you only wash your hands it
doesn’t matter, if you are taking a shower simply increase the temperature. When you finish
close the hot water first. It may appear to be a pettiness but in households with small children
these are thousands of long lasting mixings of water. When you spare a decilitres or litres of water in every washing, yearly savings can reach several cubic metres.
Single handle tap
Problem with mixing is partly solved using the single handle faucet. When you use this type of
faucet you have to learn which position of handle brings the suitable hot water. During washing
dishes it’s useful to close the tap several times, prepare another part of dishes and open it again.
Other tip: with short handle you can’t regulate the flow of the water fluently. The regulation is
usually jumping so it’s better to buy a tap with longer handle. An ideal solution is to use the
thermostatic tap in whole flat, because you can simply set up the temperature and then the flow
of water. There is no need to worry about to hot water.
Shorter water plumbing
When you move the heater from the cellar to the bathroom or as close as possible you can lower
heat losses from the pipeline. Bathroom today becomes representative part of the flat and architects don’t want to have a boiler inside, but you can simply put it in the cupboard.
Change your habits
Taking shot shower can spare almost 70 % of water compared to taking bath. There is no need to
give up relaxing in the bath only to reduce this habit. A bath contains about 150 litres of water on
the other hand you need 50 litres to take a shower.
Reduce wasting
We usually waste water and let if flow off to the sanitary plumbing because we don’t turn off the
faucet when we soap our hands, brush teeth, shampoo hair, shave ourselves, etc. There is also
one good example of the usual wasting. We usually wash our hands in very little amount of wa43
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ter and turn on the hot water, but from the tap flows the water with 20 °C and when the hot water
arrives we usually turn off the tape and let this hot water cool down in the pipeline. So try to
wash your hands with cold water because this water also stayed in the pipeline and is warmed to
20 °C. Another tip how to reduce wasting of water is using single use gloves for dirty work, using cups for brushing teeth or shaving.
4.3 Solar water heaters
Note: This type of domestic water preparation belongs to the most usual using of solar
energy. The main advantage is that the solar energy is accessible, operation of this system cost almost nothing and can be installed additionally. But the costs of investments
are quite high so the pay-off period long and the whole system depends of the sunshine
which is unpredictable.
These active solar systems accumulate collected sun energy into the storage (can be water tank,
but also pool, or gravel storage) and then the accumulated energy is used usually for domestic
hot water or heating. But a rule proceeds that longer accumulation means higher costs. Solar system has to be connected with other heating source (e.g. gas boiler, electrical boiler etc) in case
that there is no or a little sunshine (cloudy, night etc). In summer the heat carrier can be water,
but in the year-long operation the non-freezing liquid has to be used.
Note: Advantages of the solar hot water preparation:

Provides 50 % to 70 % of your annual hot water needs

20-30 years life expectancy

Solar water heaters will halve your annual hot water bills

Summer hot water is almost completely provided

Functions when overcast

Simple planning considerations
4.4 Exercise/Questions
1 Which is the suitable temperature of the domestic hot water?
………………………………………………………………………………………..
2
What does consume less water?
 Taking a bath
 Taking a shower
3 What part of the domestic hot water can be annually prepared by solar system?
………………………………………………………………………………………..
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References
Greg Pahl: Natural Home Heating: The Complete Guide to Renewable Energy Options, Chelsea
Green Publishing, 2003
Web links
http://www.engineeringtoolbox.com
http://www.rerc-vt.org/solarbasics.htm
http://www.diydoctor.org.uk/projects/domestic_hot_water_systems.htm
Key points:

Domestic hot water preparation is usually the second highest amount in the
heat consumption of the house.

Minimum consumption is about 40 litres per one person and day what is about
2 kWh. Average consumption is about 3,4 – 4 kWh per person and day.

There is a problem in summer period when losses from pipeline turn into unwanted internal gains. To avoid heat losses the pipeline should be as short as
possible and well insulated. Temperature should be about 45-60 °C.

First step is to prevent all leakages of the hot water. Dripping 10 drops in one
minute represents 40 litres per week.

Saving is taking a short shower because only one third of water is consumed in
comparison with taking a bath. Also using the showerhead for washing hands
or dishes can spare water, because the water is enriched by air and so the higher
flow is made.

There is a good possibility to use effectively renewable sources - solar especially
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5 Lighting
Learning Objective: In this Chapter you will learn:
The importance of light for humans
How use daylight and artificial light
An overview of the possible artificial light sources
What is light, how to measure and recommendations for its intensity in buildings
We need proper lighting for seeing and working. Main demand
on the internal space (from this the point of view) is the visual
comfort.
Definition: It means that the lighting environment
has to satisfy physiological, psychological and aesthetical needs of human.
Lighting includes use of both artificial light sources such as lamps and natural illumination of
interiors from daylight.
Note: Daylight is very important for human being. Without daily stimulation of the daylight the human vision can degenerate. So day lighting (through windows, skylights,
etc.) is used as the main source of light during daytime in buildings where people live or
work.
When it’s not possible to use the day lighting you can use
mixed lighting or in worst-case only artificial lighting.
Note: Using daylight during the daytime also
brings down the energy demand and also the
costs.
To provide the demanded illumination of the space the artificial lighting is usually needed. So,
artificial lighting represents a major component of energy consumption, accounting for a significant part of all energy consumed worldwide.
Artificial lighting is most commonly provided today by electric lights,
but gas lighting, candles, or oil lamps were used in the past, and still are
used in certain situations.
Proper lighting can enhance task performance or
aesthetics; while there can be energy wastage and
adverse health effects of lighting. Indoor lighting is
a form of fixture or furnishing, and a key part of
interior design. Lighting can also be an intrinsic
component of landscaping.
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5.1 Daylight
Source of daylight is direct rays of sunlight or sunlight dispersed by sky. Intensity and colour of
daylight vary during the day and the year and also depends on geographical latitude and the
weather condition. Daylight belongs to main factors of the environment and has got a huge impact on the man’s physical and psychical condition. So there are some quantity and quality demands in standards or recommendations.
Quantitative criterion is the level of intensity of daylight, quality is described by luminous flux
and the direction of the light, equability of illuminance and brightness and glare. The glare is
caused by high brightness or high contrast e.g. roof windows oriented to the sky. So it is necessary to regulate direct rays of daylight in internal spaces. There are many ways to regulate daylight. You should choose these instruments which suit best and are economical.
 Firm window covering – are situated on the external side of window
(e.g. terrace blinds)
 Moveable window covering – (e.g. window blind, curtains, movable
terrace blinds) can regulate as necessary and can be placed on both sites.
On external sited also eliminates the gains from the sun.
5.2 Artificial lighting
Artificial lighting is realized by artificial lighting sources in time when day lighting is no possible. Modern sources can create in internal space lighting which is similar to day lighting.
Note: Intensity of the light should react on the visual activity. Lower for basic activity
and higher for visual demanding activity. And also lighting has to create suitable and
pleasant environment.
The lighting is usually divided into central and local lighting. There is main
principle in designing lighting – the light has to be there where is needed
(e.g. floor, working place etc.). Also the way of lighting is important. It can
be direct, semi direct, mixed or indirect. Direct lighting means that the light
falls down on working place or the floor. Direct lighting uses whole emitted light so it’s very economical, but on contrary the dark shadows with
sharp edges originate and caused the glare. Also the ceiling and upper part
of wall are dark.
Semi direct lighting means that the source emits the light not only down but
also up to the ceiling or walls. The room appears more comfortably. The
light reflected from the ceiling makes shadows lighter and the glare is more
acceptable. The semi direct lighting is optimal and is used most often.
Mixed lighting emits light in all directions, so the illuminance of all surfaces
(floor, ceiling, walls) is same.
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Indirect lighting means that all light falls on the ceiling and upper
part of walls. Bright ceiling appears like the source with low intensity, so the whole room is illuminated uniformly without any glare.
Disadvantage of this lighting system is its high light loses caused
by the reflection.
5.2.1 Sources of light
There are two main groups of sources - thermal sources and luminescent. In thermal sources (e.g.
Sun, common bulb) the light is emitted by heating on very high temperature. In luminescent
source (fluorescent bulbs) the light springs from luminescence.
There is a list of technical data which characterizes
source which determines the quantity and quality of
the light:
 voltage (V)
 input (W)
 luminescent flux (lm)
 lumen per watt (lm/W)
 temperature (K)
Bulbs are most common and most uneconomical sources. Only about 3-4 % of the
inputted energy transform into the light, the rest is the waste of the heat. Advantage
is the low price and easy application without need to install other facilities. The colour rendition is very pleasant and approximates to the daylight. The lifetime is quite
short, about 1000 hours. The input varies from 15 to 200 W and lumen per watt
from 6 to 16 lm/W.
Halogen bulbs are quite new sources. Because of its shape they
are preferred for decorative and intimate lighting. The lumen per
watt is higher from 11 to 25 lm/W. And the lifetime is longer,
about 2000 - 3000 hours. These bulbs are manufactured in 2
types, for low voltage (12 V) with input from 5 to 75 W and for
line-voltage with input from 60 to 2000 W. They have got the
highest colour index from all sources. When you use it don’t forget that they are suitable for low voltage, the temperature of this
source is high and they warm surroundings.
Today standard fluorescent lamps are most common. They belong to the
low-pressure sources. The light is emitted by incidence of the UV light
on the layer of luminophore which covers the internal side of fluorescent
lamp. The lamps are manufactured in many colour tones from rose to
daylight. The colour index is quite good. The lumen per watt is higher
from 35 to 60 lm/W. The lifetime is quite long, 5000-8000 hours. But
often switching brings down the lifetime.
There is some anxiety about negative influence of these lamps on human organism (headache,
dry eyes, hair loss etc.) but the research has proved that this fear is idle.
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We recognize two types of fluorescent lamps: linear and compact. Linear sources are manufactured in the length 60, 120 and 150 cm and with inductive stabilizer (INDP) the fused starter for
230 V or without starter with electrical stabilizer (ELP). These sources have got about 10 times
longer lifetime and 5 times higher output than common bulbs. Compact fluorescent bulbs belong
to the group of most modern sources. Some types of these sources are produced with the same
thread as common bulbs, so you can replace bulbs easily. The lifetime is about 8 times longer
and the input about 6 times higher than bulbs.
Table 1. How much energy can be saved with replacing bulbs by fluorescent lamps?
Type of source replacing bulb
Savings
Linear fluorescent bulb Ø 38 mm with
62 %
INDP
Linear fluorescent bulb Ø 26 mm with
72 %
INDP
Compact fluorescent bulb with INDP
76 %
Compact fluorescent bulb with ELP
79 %
Linear fluorescent bulb Ø 26 mm with
82 %
ELP
Linear fluorescent bulb Ø 16 mm with
88 %
ELP
It’s percentage of not used energy.
5.2.2 Lamps
The important parts of the lighting are also the lamps. Different sources
required different lamps, for example the lamps for linear fluorescent
bulbs have got different shape and construction than lamps for bulbs.
Lamps consist of the lighting part and construction part. Lighting part can
be diffusor (which disperse the light), reflector (which reflects the light)
or refractor (which refract the light). The lamp is characterized by the efficiency of the lamp which means the ratio between lumen flux of the
lamp to the flux of the source. Lamps which are opened on the bottom
have got the highest efficiency. Common problem of the lamps is the glare from visible source.
Sources should be covered, so it shouldn’t be possible to see them from usual angles. Good
choice of the lamp brings higher working efficiency, comfort, better vision and health.
5.2.3 Energy consumption
Artificial lighting consumes a significant part of all electrical energy consumed worldwide. In
homes and offices from 20 to 50 percent of total energy consumed is due to lighting. Most importantly, for some buildings over 90 percent of lighting energy consumed can be an unnecessary
expense through over-illumination. The cost of that lighting can be substantial. A single 100 W
light bulb used just 6 hours a day can cost over 28 € per year to use (the calculation is the same
as another electric appliance). Thus lighting represents a significant component of energy use
today, especially in large office buildings where there are many alternatives for energy utilization in lighting.
There are several strategies available to minimize energy requirements in any building:
 Specification of illumination requirements for each given use area.
 Analysis of lighting quality to ensure that adverse components of lighting (for example, glare
or incorrect colour spectrum) are not biasing the design.
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 Integration of space planning and interior architecture (including choice of interior surfaces
and room geometries) to lighting design.
 Design of time of day use that does not expend unnecessary energy.
 Selection of fixture and lamp types that reflect best available technology for energy conservation.
Note:

Training of building occupants to utilize lighting equipment in most efficient manner.

Maintenance of lighting systems to minimize energy wastage.

Use of natural light - some big box stores are being built with numerous plastic
bubble skylights, in many cases completely obviating the need for interior artificial lighting for many hours of the day.
5.3 Exercise/Questions
1 What are quantitative and qualitative criterions of the light?
………………………………………………………………………………………..
2 Why is it necessary to regulate direct rays of daylight in internal spaces?
………………………………………………………………………………………..
3 What is direct lighting?
……………………………………………………………………………………….
4 Which technical data does characterize source?
……………………………………………………………………………………….
References
Fetters, John L.: The Handbook of Lighting Surveys & Audits, CRC Press, 1997
Web links
http://www.iesna.org/
http://www.enlighter.org/
http://www.newbuildings.org/ALG.htm
http://www.lrc.rpi.edu/
http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/97/970109.html
http://www.lightingmanual.com/
http://www.vgklighting.com/
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Key points:

We need proper lighting for seeing and working. Day lighting (through windows, skylights, etc.) have to be used as the main source of light during daytime in buildings where people live or work

Intensity of the light (illuminance) should react on the visual activity. Lower
for basic activity and higher for visual demanding activity. This is closely connected with electric input and consumption of artificial sources of light; higher
intensity higher input higher consumption.

It is possible to save 60 - 80 % of energy with replacing bulbs by fluorescent
lamps.

The simplest and most obvious way to eliminate useless energy consumption is
to switch off lights when not necessary.
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6 Electric appliances and electronic devices (and solar PV)
Learning Objective: In this Chapter you will learn:

The unit of electricity measurement and how to calculate it

How to read the European Energy Label for electric appliances

An overview of the characteristics of the main appliances used in households
and how to save energy using them properly.
6.1 Overview
In our homes, we are surrounded by all kinds of electrical and electronic equipment that we use
regularly to meet our needs. We consider their use as being so elemental that sometimes we forget the associated energy cost.
In Europe, electrical appliances account for about 8% of a typical household’s energy consumption.
Note: The percentage is much higher if we refer to a household’s electricity consumption. Consumption by all-electrical appliances and lighting represents about 55% of the
electricity used by households. The appliances include the six large consumers of electricity (refrigerators, deep freeze, washing machines, dishwashers, TV and dryers), and
many small appliances.
Main appliances include the following:

Refrigerator and deep freeze

Washing machine and tumble dryer

Dishwashers

Immersion heater

Hairdryer

Room air conditioners

Electric oven
Apart from the purchase price, which normally is the driver in the criteria for choosing, the cost
of operating the appliances during their lifetimes should also be seriously considered, that is the
cost of the utility bill every month for many years (depending on the lifetime), due to their electricity consumption. Models with high energy-efficient performance usually have a higher initial
purchase cost, but they permit the saving of significant amounts of energy costs over their lifetime (and thus save money).
Do you know what an Energy Label is?
One of the main aims of the EU Energy Label is to help householders
make informed decisions about the purchase of energy-consuming appliances. It is also an incentive for manufacturers to improve the energy
performance of their products.
The Energy Label is compulsory only for a certain group of products,
light bulbs, cars and most electrical appliances (e.g., refrigerators, stoves,
washing machines, as listed above). The other appliances, which have
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lower power in general, are not covered by the Energy Label. Some of them are: toasters, fans,
clothes irons, blenders, etc.
Definition:The Energy Label is a sticker providing clear and easily recognizable information about the energy consumption and performance of products and must be
attached visibly to new appliances displayed for sale.
An important part of an energy label is the energy-efficiency rating scale, which provides a simple index composed of a code of letters and colours ranging from green
and the letter A, the most efficient, to the colour red and the letter G, the least efficient.
The energy consumption figure shows you the units of electricity use
in kWh to allow comparisons between models.
Each letter that is lower in the scale, away from A, means an increase
in energy consumption by about 12–15% more than the letter that precedes it. Thus, we can say that, for instance, a washing machine of
”Class A” consumes up to 24% less than one of equal benefits and
class C, and up to 36% less than a Class D.
Only in the case of cold appliances (refrigerators, freezers, etc.), must
you add two rows from the top, to include Class A+ and A++, expressing an even lower relative consumption.
Therefore, if you consider that the useful life of a home electrical appliance is more than ten
years, the energy savings to be gained are very important.
How do you estimate appliance electricity consumption? How much electricity do appliances
use?
The first step to making your home more energy efficient is to understand where you use energy.
You can make the greatest impact on reducing your electric bill by focusing on the areas where
you use the most energy.
But to do that it’s useful to know the following two basic concepts!!
1. Electric Power
The electricity consumption of an appliance firstly depends on its
“electric power” or the wattage, that is to say the maximum power drawn
by the appliance. You can look at the wattage of most appliances
stamped on the bottom or back of the appliance, or on its nameplate.
Usually it is expressed by watts (W) or kilowatts (kW)
(Remember that 1 kilowatt (kW) = 1,000 Watts)
Thus, if you have 500 Watts, it means 0.5 kW (obtained by dividing
500/1,000).
Some examples of the wattage range for various electrical appliances are shown here, bearing in
mind that they can vary much according to type, size and working conditions.
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Appliance
Wattage
Appliance
Wattage
700–1200
Air conditioner (room)
1000 +
1000
Aquarium
50–1210
Blender
300
Dehumidifier
800
Microwave oven
700 - 1500
Electric blanket
200
Clothes Iron
750 - 1200
Water heater (150 litre)
Clothes washer
900
CD player
45005500
30
Clothes dryer
Fan (table)
2000
5000
1200
1500
20 - 250
Fan (ceiling)
Coffee
cups)
Toaster
maker
(4/10
Personal computer + monitor
Lap top
120 - 160
Television (25” / 19”)
150 - 80
10 - 50
Radio (stereo)
50 - 300
Vacuum cleaner
1200
Fryer
1200
Hair dryer
1000 +
Refrigerator
200 - 800
Dishwasher
-
50
Table 6 .Typical Wattages of Various Appliances
2. Electricity Consumption
When you use electricity to watch television (or just keep to it on without watching!) for 1 hour,
Note: In other words, consumption is
obtained by multiplying power by time.
you use 150 watt-hours of electricity.
And, 1,000 watt-hours equals 1 kilowatt-hour
(1,000 Wh = 1 kWh).
But, it is important to bear in mind that, since
many appliances have a range of settings (for example, the volume on a radio, the temperature selected on an air conditioner), the actual amount of
power consumed depends on the setting used at any one time.
It means that if an appliance is not running at its maximum wattage (for example not the maximum air-conditioning temperature), the electricity consumed does not exactly equal power per
time, but rather, less. This is obtained by multiplying by the so-called “demand factor”,* which
is a number equalling 1 (running at maximum wattage) or less (not at maximum wattage).
Consumption Calculation:
First of all, you already know that the consumption of electricity by electric appliances is measured in a unit termed “kilo-Watt-hours” (kWh).
In order to estimate the electricity consumption of an appliance, these few
steps can be followed:
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1.
Look at its wattage (the plate gives you its installed power in watts or kilowatts).
2
Make an estimation of how many hours* it runs per day (for instance, TV 3 hours, refrigerator 24 hours).
Multiply the wattage by the hours the appliance is used (run per day).
The formula is:
Power (kilowatts) x Time (hours used Per Day) = Energy consumption (kWh).
3
Then, multiply the daily consumption by the number of days the appliance is used during
the week, month or year (depending on the period of consumption you want observe).
Finally, you can calculate the annual, monthly or daily cost to run an appliance by multiplying
the electricity consumption (kWh) by the price of a unit of kWh (i.e., 9 cents€/kWh).
The formula is:
Energy consumption (kWh) x Electricity price (cents€ / kWh) = Cost (€).
Examples of Calculation:
 Clothes Iron:
Electric Consumption = (850 Watts × 1 hour/day × 3 days/week × 4 weeks/
month) ÷ 1,000*
= 10.2 kWh/month
Money Cost = 10.2 kWh × 13 cents€/kWh = 132.6 cents€/month
(.........× 12 month/year = 1,591 cents€/year = 15.91 €/year).

Personal Computer and Monitor:
Electric Consumption = (120 + 160 Watts × 4 hours/day × 365 days/year) ÷
1,000* = 408.8 kWh
Money Cost = 408.8 kWh × 13 cents/kWh = 5,314 cents€/year = 53.14 €/year.
*Remember that 1,000 Wh = 1 kWh. In the above formulas, division by 1,000
is done to transform watt hours (Wh) into kilowatts hours (kWh), which is a
more suitable way to express electricity consumption. Observe: if, in the example, electricity consumption was expressed by watts, the result would be =
10,200 Wh (for the clothes iron) and 408,800 (for the PC and monitor). It
would mean larger and uncomfortable numbers!!
Note that: the electricity price is variable among European countries. Check
your utility bill for your price!!
Reading the utility bill
Your utility bill usually shows what you are charged for the kilowatthours you use, and shows also how many kilowatts hours (kWh) have
been consumed. The multiplication between these two factors, plus the
addition of others elements (taxes, administrative costs, etc.) gives you
the amount to pay.
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Note: In Europe, the average residential rate is 20 cents per kWh, varying from 9 cent€/
kWh (Bulgaria) to 32 cent€/kWh (Denmark). A typical European household consumes
about 4,500 kWh per year, costing an average of €900 annually.
6.1.1 General tips on how to save energy
Two basic and simple points to be observed:

Take care when buying electrical appliances. Purchase energy-efficient products (such as
Class A) and get used to looking at the electric power (wattage).

Operate them efficiently: try not to use appliances if they are not necessary, and switch off
them when not used.
Note: Many appliances continue to draw a small amount of power when they are
switched “off”. These “phantom loads” occur in most appliances that use electricity,
such as VCRs, televisions, stereos, computers, and kitchen appliances.
Most phantom loads will increase the appliance’s energy consumption by a few watt-hours.
These loads can be avoided by unplugging the appliance or using a power strip and using the
switch on the power strip to cut all power to the appliance.
6.2 Electric appliances
6.2.1 Refrigerators/ Fridges:
Nowadays, refrigerators are necessary devices in homes for better preservation of food.
Note: Because they are machines that operate 8,760 hours a
year (all year), their consumption is the highest in a home.
Although these appliances are relatively low-power, their high number of
running hours makes them greater consumers of energy than others with
much greater power.
Compare:
Air conditioner:
Refrigerator:
Electric Power = 2 kW
Electric Power = 0.2 kW
Hours of operation = 480 hours/year
Hours of operation= 8,760 hours/year
Electricity consumption = 2 x 480 = Electricity consumption = 0.2 x 8,760 =
960 kWh/year
1,752 kWh/year
As can be seen, a refrigerator consumes more energy than an air conditioner that has wattage 10
times higher.
As mentioned, cold appliances (refrigerators, freezers, etc.) are
rated with two more energy-efficiency levels in the “Energy
Label”, i.e., Class A+ and A++, expressing an even lower relative consumption.
56
A+ A+ A B C D E F G
+
<3 <42 <55 <75 <90 <10 <11 <12 >1
0
0 0 5 25
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A new refrigerator with an A+ label uses at least 42% less electricity than conventional models
(Class D or E), and even less than 30%, if the new refrigerator is labelled with A++.
In cold appliances, it is very important to avoid losses of cold air, as they will need to produce
the lost cold air again.
The main causes of cold losses are:

Insulation: the heat transfer through the material that makes up the walls of the refrigerator.

Food: the heat transfer from the food (as food deposited initially has a greater temperature
than refrigerator).

Door seals (gasket): the heat transfer through the board which is responsible for maintaining airtightness.

Door open: the heat transfer caused when the door is opened.
8%
9%
Door ope n
15%
Door s e als
Food
Ins ulation
68%
Graph 2 . Cause of cold losses
Refrigerator and Freezer Energy Tips:

Look for the ENERGY LABEL when buying a new refrigerator and select class A+ or
A++.

Select a new refrigerator that is the right size for your household needs. The bigger it is,
the higher the energy consumption gets.

Do not put in hot food.

When you have to thaw food from frozen, do it in the refrigerator compartment and not
outside of it, as that will exploit the colder temperature of the frozen food.

Make sure your refrigerator door seals are airtight. Test them by closing the door over a
piece of paper. If you can pull the paper out easily, the seal may need replacing.

Keep the doors open the shortest time possible.

Do not install a refrigerator in warm places and with little ventilation.

Don’t keep your refrigerator or freezer too cold. Recommended temperatures are 5°C for
the fresh food compartment of the refrigerator and -18ºC for the freezer section.

Regularly defrost a manual-defrost refrigerator and freezer; frost decreases the energy efficiency of the unit. Don’t allow frost to build up more than 3mm thick.
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6.2.2 Washing machines:
This is an essential appliance present in almost all European homes. The
number of times it is used depends on the users’ habits, but can be estimated, on average, to between three and five times per week. After the refrigerator and TV, it is the appliance that consumes more energy than any
other in European homes.
The machine washes clothes by using hot water and detergent in a process
of spinning on a drum load.
Note: The largest energy consumption is not in moving cargo, but in heating the water,
which is done by electrical resistance, using about 85% of the total energy.
The other important consumption factor is related to water use, which can be approximated to
30–50 litres.
The Energy Label for washing machines shows all these issues: effectiveness of washing, effectiveness of spin, water and energy consumption per cycle.
Advice on their use:

Buy machines with a Class A Energy Label.

Wash full loads. If you are washing a small load, use the appropriate water-level setting,
or better, wait until you have more dirty clothes.

Wash using cold water or use a low temperature setting whenever possible. 30ºC would be
sufficient!!!

Avoid using the dry function – for that there is the sun and wind!
The new bi-thermal machines operate with two sources of water, hot and cold. The hot
water is taken from the hot water system that is preheated and allows less energy consumption.
6.2.3 Dishwashers:
The use of this appliance is growing day by day, according to the increase in our level of comfort demand and the decrease of family spare
time.
One out of four European families has got a dishwasher and uses it almost every day, making it one of the most energy-using consumer appliances.
Note: As in the washing machine, approximately 70–80% of the electricity used goes
to heating the water.
Currently, there are devices with many setting programs which are capable of selecting mediumcapacity and low-temperature modes, allowing an energy consumption reduction.
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Tips on its use:

When shopping for a new dishwasher, look for the Energy Label Class!

Be sure your dishwasher is full, but not overloaded, when you run it.

Set the water heater in your home to a lower temperature.

Let your dishes air dry; after the final rinse, leave the door open so the dishes will dry
faster.
6.2.4 Ovens:
There are two main types of ovens, gas and electric. The first ones are the
most recommended from the standpoint of efficiency, but electric ovens
are more widespread in European families, although they are more energy
consuming.
Although ovens consume a lot of energy according to their wattage, over a
year, the total energy consumption is relatively low, thanks to their lower
employment in terms of time (hours).
Tips on their use:

Leave the oven door closed during cooking. To know the status of the cooking food, simply use the light. Each time you open the door, you lose about 25–50 degrees of heat.

Try to get used to its maximum capacity and not use the oven only to heat a little food. For
this, use the microwave instead of the conventional oven, it can save between 60 and 70%
of the energy and is, in addition, faster.

Turn off the oven a little before the food is cooked, as the residual heat will be enough.
6.2.5 Small home appliances:
They can be divided into two groups:

those which do some mechanical work, such as to beat, to cut up, to squeeze, and in general are of low power;

those which produce heat, such as irons, toasters, hair dryers, electric blankets with higher
power, and thus, lead to significant consumption.
Note: These electric appliances are not covered by the Energy Label, but they are not
for that reason energy innocuous!!
Look at the power of the following devices:
Vacuum cleaner = 1,300 Watts
Iron = 1,000 Watts
Hair dryer = 1,200 Watts
Food mixer = 1,800 Watts
Note: Only the intelligent use of this range of products can prevent energy waste!!
Thus, do not dry clothes using a tumble dryer!! ...unfortunately some people do that. .
Tips on their use:
 Do not leave appliances on unnecessarily.
 Use your hands to do work like squeezing an orange or beating eggs.
Choose with care when shopping for appliances. Look at their wattage and not only at price.
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6.2.6 Home electronic equipment – Entertainment and home office devices:
These are devices that are increasingly widespread and are being employed
more and more hours a day. Every year, electronic products manufacturers
emerge with more sophisticated equipment, and thus, offer more attractive entertainment.
Note: The energy use of electronic equipment often goes unnoticed.
Instead, an estimated 10% to 15% of all electricity used in European
homes can be attributed to the running of electronic devices.
The vast majority is consumed by home
entertainment systems and home office
equipment. But small energy users, including portable devices with battery chargers,
add a significant weight, not because they
use a lot of energy individually, but because of their numbers and the many hours
of activity.
In this group are: televisions and home cinemas, VCRs and DVD
players, combination units (TV/VCR; TV/DVD), home audio, computers, video game consoles, etc.
Power modes
All these products incorporate various operating modes. One of them
is the stand-by mode that can be turned on and off via a remote control. This is virtual disconnection, because devices on stand-by consume roughly between 10 and 15% of normal conditions. Thus, it is
recommended to switch off completely if you are not going to be
used them.
Operation modes are as following:
Table 7 Operating modes
Mode
Definition
Examples
Active
(In-Use)
Appliance is performing its primary function.
TV
displays
picture
and/or
VCR
records
or
plays
back
Printer prints document.
Active standby
Appliance ready for use, but not performing
DVD
player
on
but
primary
function.
Cordless appliance charging.
Appears on to consumer.
Passive standby
Appliance
is
off/standby.
Microwave not in use, but clock is on.
Appears off to consumer, but can be activated
CD player off, but can be turned on with reby remote control or is performing peripheral
mote control.
function.
Off
Computer
speakers
are
off,
Appliance is turned off and no function is being
but
plugged
in.
performed. Consumer cannot activate with reTV is not functioning and cannot be turned on
mote control.
with remote.
60
not
sound.
tape.
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Below is a table of common electronic equipment and the average energy used in each mode and
per year (in order from the most energy-intensive to the least). In the last two columns, the relatives annual energy consumption costs are showed, considering the lowest and highest European
electricity price.
Product
Passive
Standby or
Off (watts/
year)
Active
Standby
(watts/
year)
Active
(watts/
year)
Average
Annual
Energy
Use
(kWh)
Annual Energy Cost
(Euro) EU
Annual Energy Cost
(Euro) EU
lower price
(0,09 €/kWh)
higher price
(0,32 €/kWh)
Home Entertainment
Plasma TV (<40")
3
-
246
441
39,69
141,12
DVR/TiVo
37
37
37
363
32,67
116,16
Digital Cable
26
26
26
239
21,51
76,48
Satellite Cable
12
11
16
124
11,16
39,68
LCD TV (<40")
3
-
70
77
6,93
24,64
Video Game Console
1
-
24
16
1,44
5,12
DVD
1
5
11
13
1,17
4,16
Desktop Computer
4
17
68
255
22,95
81,6
Laptop Computer
1
3
22
83
7,47
26,56
LCD Monitor
1
2
27
70
6,3
22,4
Modem
5
-
6
50
4,5
16
Wireless Router
2
-
6
48
4,32
15,36
Printer
2
3
9
15
1,35
4,8
Fax
4
4
4
26
2,34
8,32
Mutli-Function Printer/
Scanner/Copier
6
9
15
55
4,95
17,6
Home Office
Rechargeable Devices
Power Tool
4
-
34
37
3,33
11,84
Cordless Phone
2
3
5
26
2,34
8,32
Electric Toothbrush
2
-
4
14
1,26
4,48
MP3 Player
1
-
1
6
0,54
1,92
Cell Phone
0
1
3
3
0,27
0,96
Digital Camera
0
-
2
3
0,27
0,96
Table 8 Electronic equipment and average energy consumption
External Power Adapter
Electronic products run on low-voltage direct current (DC), and therefore
require a power adapter to transform the 120-volt alternating current (AC)
supplied at the power outlet. Some larger products, like TVs, stereos and settop boxes, incorporate the power supply into the body of the product. Others
use external power supplies, the familiar “wall packs” that increasingly compete for space in our sockets and power extension strips.
Note: These power supplies consume electricity whether or not the
product is on or off, and even if it is disconnected! You’ll know a
wall pack is using energy when it has been plugged in for a while
and it is warm to the touch.
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Tips and hints:
There are several steps you can take now to minimize the energy used by the electronics in your
home:

Unplug It. The simplest and most obvious way to eliminate power losses is to unplug
products when not in use. Search the wall sockets in your house for hidden unconnected
chargers and other devices that don’t need to be plugged in. When you detach your cell
phone or similar device from its charger, unplug the charger too.

Use a Power Strip. Plug home electronics and office equipment into a single power strip
with an on/off switch. This will allow you to turn off all power to the devices in one easy
step.
Especially for Computers:

When not using the computer, even for short periods, switch off the screen.

Use screensaver black, as this consumes less energy.

Remember, you must enable the power management features (low-power “sleep mode”)
on your computer. It is standard in Windows and Macintosh operating systems. Simply
touching the mouse or keyboard “wakes” the computer and monitor in seconds.
Energy Star
Under an agreement reached between the United States and the European Union, an energy label called “Energy Star” is used for many
electronic devices (monitors, computer equipment and imaging equipment).
This label indicates equipment which has the ability to disconnect and
go into a low-power “sleep mode” after a period of inactivity. Thanks
to this mode, a reduction of energy consumption is achieved by 75%
compared to the performance of normal “off” functions.
The ENERGY STAR label ensures a low standby power use for these appliances — in most
cases, only 1 watt or less.
Tips and hints:
There are several steps you can take now to minimize the energy used by the electronics in your
home:
Look for the ENERGY STAR label when purchasing a new TV, DVD Player, VCR, audio system, computer, printer, fax, and copier.
6.3 Exercise/Questions
1
How much do electrical appliances account for a typical household’s energy and electricity consumption (in %)? ...........................................
2
What information is provided in the EU Energy Label? .................................................................................................And what letter/colour
rate is the most efficient rate?
................................................................................................
What kind of appliances have been given two more energy ranges (A+ and A++)?
................................................................................................
3
4
According to the Wattage Table, write how much power do the following devices use
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(expressed by kW):
Blender =.....................
Vacuum cleaner =..................
5
Electricity consumption calculation. Fill in the gap:
Power (W)
X
Time = Electricity (W) X
(h)
1100
100
600
800
150
X
X
X
X
X
4
10
4
4
4
=
=
=
=
=
X
X
X
X
X
Price
(cent€/
kWh)
15
15
15
15
15
=
Cost
=
=
=
=
=
6
How much electricity will the following appliances consume if they are used for 2.5 hours
each?
Blender = kWh.....................
Vacuum cleaner = kWh..................
And if are they used 0.5 hour a day during 12 days a month?
Blender = kWh/month.....................
Vacuum cleaner = kWh/month..................
7
How much electricity does a typical European household consume approximately? ........................................; and how much does it cost? .........................
8
Which is the household appliance using the highest consumption (on average) per year?
And why?
....................................................
9
Where would be the best place to site a refrigerator? (Tick the Wrong answer/s):
Close to the oven ¨

In a small storage room without windows

Wherever it is far from warm spaces ¨

10
In which task do washing machines, like dishwashers, consume the largest amount of electricity?
.........................................................................................
11
Answer the following statements with right (R) or wrong (W):
Ovens don’t lose energy by opening their doors during cooking ........
Small home appliances are covered by the Energy Label.......
Some small home appliances have a large wattage........
12
How much electricity do home electronic equipment account for in EU homes on average
(%)? ............................
13
Check for at least two electric or electronic household appliances that, even if they have
lower wattage, register large electricity consumption during a year:
– ............................
– ...............................
Explain why: .........................................................................
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14
What is the average cost of a kilowatt-hour of electricity for residential customers in your
country?
..................................................
Glossary
Demand Factor: the ratio of (a) the maximum real power consumed by a system to (b) the
maximum real power that would be consumed if the entire load connected to the system were to
be activated at the same time.
Web links
www.energystar.gov/
http://www.energysavingtrust.org.uk/
http://www.energylabels.org.uk/eulabel.html
http://www.energysavingcommunity.co.uk/
References
VV. AA.: Guía práctica de la energía. Consumo Eficiente y Responsable (Practical Guide for
Energy. Efficient and Responsible Consumption), Instituto para la Diversificación y Ahorro de la
Energía (IDAE), 2007.
Key points:

The purchase price of electric appliances and electronic devices, usually is the
driver in the criteria for choosing, however models with high energy-efficient
performance have a higher initial purchase cost, but they permit the saving of
significant amounts of energy costs (and thus, of money).

The electricity consumption of an appliance firstly depends on its “electric
power” or the wattage, that is to say the maximum power drawn by the appliance. Then consumption is obtained by multiplying power by time of appliance
use.

The Energy Label is a sticker providing clear information about the energy
consumption and performance of products. For instance the energy-efficiency
rating scale, which provides a simple index composed of a code of letters and
colours ranging from green and the letter A, the most efficient, to the colour red
and the letter G, the least efficient.

The largest electricity consumption in appliances such as washing machines
and dishwashers is in heating the water, which is done by electrical resistance,
using from 70% up to 85% of the total energy.

Home electronic equipment and entertainment and home office devices are increasingly being employed more and more hours a day. Their energy use often
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
goes unnoticed; instead, an estimated 10% to 15% of all electricity used in
European homes can be attributed to them.
The simplest and most obvious way to eliminate power losses is to unplug
products when not in use.
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6.4 Photovoltaic energy
Learning Objective: In this Chapter you will learn:

Solar energy fundamentals and how solar energy is transformed into electricity

Main types of photovoltaic cells

A basic sizing of a photovoltaic system
6.4.1 Solar energy
Climate change, atmospheric pollution and, in general, the alarming environmental situation,
mainly caused by the continued use of fossil energy sources, are slowly becoming growing concerns and are leading to the development of new alternatives for supplying electricity, wellknown as Renewable Energies.
Note: One of them is solar energy, the source of which is simply the sun; it is available
for free, is inexhaustible and can be used in different ways
What is Solar Energy?
Every day the sun sends out an enormous amount of energy in the form of radiation. Like others
stars, the sun is a large ball of gases, mostly hydrogen and helium atoms, in a constant combustion process, or said better, in a combining process among those atoms called nuclear fusion.
Simply said, the hydrogen atoms combine or fuse to form helium in the sun’s core under extremely high temperature and pressure conditions. Precisely four hydrogen nuclei fuse to become
a helium atom which contains less matter than the previous four of hydrogen. This loss of matter
is what is emitted into space as radiant energy, the first source of life on the planet earth.
Fig.14 Energy radiations
Only a smart portion of the energy radiated hits the earth, one part in two billon, the remainder
being spread into space. Of that small portion, about 15% of the sun rays are reflected back into
space, another 30% cause water evaporation which is stored in the atmosphere producing rainfall, and finally, solar energy is also absorbed by plants, the land and the oceans, allowing vegetable life through the photosynthesis mechanism. Only the rest could be used to supply our energy needs, yet this amount of energy is enormous.
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How can we use solar energy?
We have many options for using solar energy at home, school and in buildings in general. The
three main ways are:

Passive heat: it consists of getting use by the heat naturally received from sun. The main
application is in the design of buildings where less additional heating is required (look at
the chapter on building design).

Solar thermal: where we use the sun’s heat to provide hot water for homes or swimming
pools or also heating systems (look at the chapter on water).

Photovoltaic energy (PV): The direct transformation of solar energy into electricity, able to
run appliances and lighting. A photovoltaic system requires daylight – not only direct
sunlight – to generate electricity.

sizing of a photovoltaic system
6.4.2 The process of turning sunlight into electricity.
“Photovoltaic” comes from the two words: “photo”, from the Greek root word, meaning light,
and “voltaic”, from “volt”, which is the unit used to measure electric potential.
Definition: Photovoltaic systems use cells to convert
solar radiation into electricity. The cell consists of one or
two layers of a semi-conducting material.* When light
shines on the cell, it creates an electrical field across the
layers, causing electricity to flow. The greater the intensity of the light, the greater the flow of electricity is.
Currently, commercial PV cells
convert only between 6% and 15%
of the radiant energy into electricity.
Nonetheless, although it may not
seem so, it is a good result and great
possibilities are inherent in this
technology, thanks to important advances achieved by scientific research in the last few years, mainly
in the field of new materials which
are able to achieve the photovoltaic conversion.
The most common semi-conductor material used in photovoltaic cells is
silicon, an element most commonly found in sand. There is no limitation
to its availability as a raw material; silicon is the second most abundant
material on earth mass. A photovoltaic system, therefore, does not need
bright sunlight in order to operate. It can also generate electricity on
cloudy days. Due to the reflection of sunlight, slightly cloudy days can
even result in higher energy yields than days with a completely cloudless
sky.
How does a PV cell work?
The most important parts of a PV system are the cells which form the basic building blocks of
the unit, collecting the sun’s light, the modules which bring together large numbers of cells into a
unit (and in some situations, the inverters used to convert the electricity generated into a form
suitable for everyday use).
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Fig.15 Solar cell functioning
Regardless of size, a typical silicon PV cell produces about 0.5–0.6 volts DC (Direct Currency).
The current (and power) output of a PV cell depends on its efficiency and size (surface area), and
is proportional to the intensity of sunlight striking the surface of the cell.
Note:
For example, under peak sunlight conditions, a typical commercial PV cell with a surface area of 16 cm² will produce about 2 watts peak power. If the sunlight intensity were
40 % of peak, this cell would produce about 0.8 watts.
However, 2 watts are not enough to run any electrical devices. But hundreds of cells
composing a PV module, sometimes also called a panel, running for more time, will result in a power output from 10 watts to 300 watts, depending on the technology used –
even more if several modules are connected together (called arrays).
Fig. 16 Photovoltaic elements
For example, a typical commercially available 160-watt-power PV module could have a
surface area of 1.2 square metres (1.5 m x 0.8 m).
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Cell-production process
There are several kinds of available technology, mainly differentiated by the type of raw material
composing the cell and the method of building the modules. The most common are as follows.
PV cells are generally made from Crystalline Silicon, with two main possibilities: from thin
slices cut from a single crystal of silicon (monocrystalline) or from a block of silicon crystals
(polycrystalline), or mixing silicon with others semi-conductor materials (amorphous); their efficiency ranges between 12% and 17%. This is the most common technology representing about
90% of the market today.
Fig.17 Types of PV cells
The other type available is the Thin Film technology. The modules are constructed by depositing
extremely thin layers of photosensitive* materials onto a low-cost backing such as glass,
stainless steel or plastic. Thin film manufacturing processes result in lower production costs
compared to the more material-intensive crystalline technology, a price advantage which is currently counterbalanced by substantially lower efficiency rates (from 5% to 13%).
There are several other types of photovoltaic technologies developed
today and starting to be commercialized, or still at the research level,
such as the Flexible Cells, based on a similar production process to thin
film cells – when the active material is deposited in a thin plastic, the
cell can be flexible.
In recent years, scientific research has achieved important
improvements in the PV cell technology by achieving 40% efficiency with a
multi-junction solar cell made out of various elements (Gallium, Indium, Arsenic
and Germanium), but the high production costs made it not commercially available.
6.4.3 Photovoltaic applications
The photovoltaic technology can be used in several types of applications.

The first and probably most “high tech” applications have been developed for
spacecrafts.

Already familiar is the sight of solar-powered calculators, toys, lighting
and phone boxes, and many others consumer goods using solar cells.

Where no mains electricity is available, off-grid applications are used to
bring access to electricity to remote areas, such as remote telecommunication stations, mountain huts, developing countries and rural areas.

It is also ever more common to see medium and large power plants that
lie in countryside fields, so-called grid-connected power plants.

Here, it is our prime interest to throw light on the buildings which integrate photovoltaic systems.
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These PV systems can cover roofs and facades, thus contributing to the
reduction of the energy which buildings consume. They don’t produce
noise and can be integrated in very aesthetic ways.
European building regulations have been and are being reviewed to
make renewable energies a required energy source in public and residential buildings. This action is accelerating the development of
ecobuildings and positive energy buildings (E+ Buildings), which open up many opportunities
for a better integration of PV systems in the built environment.
Regarding their functioning scheme, usually these systems carry a
connection to the local electricity network which allows any excess
power produced to be fed into the electricity grid and to be sold to the
utility. Electricity is then imported from the network when there is no
sun. An inverter is used to convert the direct current (DC)* power
produced by the system to alternative current (AC) power for running
normal electrical equipment.
6.4.4 How much electricity can a PV system produce?
Depending on the location of the solar facility, more or less energy is available, and therefore,
more or less electricity can be produced.
Thus, the answer lies in several factors, and the main steps to take into account are as follows:
1. the amount of energy that reaches a certain location; solar irradiation and hours of sun;
2. the correct position and inclination of the modules;
3.
technology employing photovoltaic modules.
1. Energy coming from the sun is measured by the “solar irradiance”, that is defined as the energy power of the sun which a certain place receives per unit area (expressed in watts or kWs per
square metre).
Multiplying irradiance data (the power) by the sunshine hours of a given place (time duration),
we obtain the sum of irradiation (energy). In other words, the irradiation indicates the quantity of
solar energy (kWh) received on a square metre of surface (kWh/m²) during a given time. For example, multiplying by the daily sunshine hours averaged in a given place (or hours/day), we obtain the daily irradiation (kW·h/m²·day).
Graphically, the following map shows the yearly irradiation for Europe.
2. Another crucial step is the PV modules position with respect to the sun, with the objective of
getting as long a radiation exposure as possible. The longer the hours of direct solar exposure,
the more electricity production is achieved.
Three aspects have to be considered for positioning:

Orientation: a system for solar power should be oriented as much as possible to the south
(if you are located in the northern hemisphere).

Inclination (angle): the PV modules should have an inclination
which allows perpendicular facing towards the midday sun. This
coincides, as general rule, with the latitude of the geographic location. In Europe, the optimum inclination angle of PV modules
to maximize yearly energy yield goes from 26º in the south of
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Greece to 48º or even more in the north of Europe. The reason for this is, in the south, the
sun travels quite perpendicularly, and thus, modules assume a quite horizontal inclination
in order to get as long a use as possible from the irradiation. In contrast, the opposite happens to the north, where the sun has a lower trajectory with respect to the horizon, and
thus, modules need to be inclined more vertically. The same concept is valid for the seasons: the sun is higher in summer than in winter.
Fig.18 Sun positions
Shadow and wire: these should be avoid as much as possible, such as any shadows made by
buildings, mountains or trees. Any shadow will affect the electricity output by reducing it.
3. The third step regards the technology used for which, as mentioned above, there are several
options depending mainly on the material composing PV cells. Here the key factor is represented
by the “conversion efficiency” that can reach as much 17% for the better technology commercially available. This means that a small portion of the irradiation received can be transformed
into electricity.
Nowadays, Solar Maps and interactive application services are available for each country. They
include all those above-listed factors and deliver a comprehensive estimation of the amount of
electricity production achievable in a certain place. Thanks to these tools, we can know our region and local potential, and thus, are able to calculate how much electricity could be produced
by a given solar facility.
One of those tools is the Photovoltaic Geographical Information System (PVGIS) available
online with a very friendly and funny application.
Visit the website of the Joint Research Centre to discover how much solar energy strikes your
region (http://re.jrc.ec.europa.eu/pvgis/).
Let’s calculate together...
The following map (from the PVGIS) shows the amount of electricity generable in the European regions by photovoltaic systems.
It already takes into account: quantity of solar irradiance, average hours of sun
and other factors, such as conversion efficiency of PV technology, optimal
modules orientation and inclination, and wire losses.
In brief, it allows a good estimation of the solar energy potentiality of a given
site.
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Fig.19 Photovoltaic Geographical Information System (PVGIS)
The more red-coloured a given site is, the better energy performance there is.
At the bottom of the map, the same colour legend shows two important indicators:

The yearly sum of irradiation incident on a square metre of photovoltaic
modules, expressed by kWh/m2 (Global irradiation).

The early sum of potential solar electricity generated by a 1 kWp system
installed, or kWh/kWp (Solar electricity).
The first row of data (Global irradiation) refers just to the irradiation on one
square metre of surface per year. Note that it doesn’t mean that 1 m2 actually
produces the value indicated. As said before, not all of the sunshine that strikes
a PV cell will be converted into electricity, due to the technological limitations
(“conversion efficiency”) and other losses.
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The second row of data (Solar electricity) directly informs how much electricity a 1 kW PV system could generate, installed in a given place. The estimation value already includes various losses and technology limitations.
What you need is just to search for your city and check the right value......
Example:
 A one-kilowatt (kW) PV system installed in Sardinia (Italy) can produce
approximately 1,350 kWh of electricity per year (look at the map).
Obviously, for a two-kilowatt system, it is (1,350 x 2) 2,700 kWh per year of
electricity.
Note that: This is almost the load of a typical European customer. The average residential customer uses 3,200 kilowatt-hours (kWh) of electricity per
year (average in Europe is 27).
How large will the PV system be?
To obtain a one-kW rooftop system and considering the installation of 200watt power modules:

About 5 modules would needed (obtained by: 1 kW (or 1,000 W)/200 = 5).
But note that module banks (arrays) must never count with uncoupled modules, which means that a total of at least 6 modules are suitable. In addition it
is even better to over-dimension the system, due to different kinds of losses.
Finally, if each module is 2 square metres, the surface covered by PV modules
will be 12 square metres (resulted from: 2 m2 x 6 modules).
6.5 Exercise/Questions
1
What does the word photovoltaic mean?
.................................................................................................
.................................................................................................
2
How efficient are PV cells today? Explain what the conversion efficiency means?
.................................................................................................
.................................................................................................
3
Do PV cells produce AC (alternate current) or DC (direct current) current? ..................................................................................
4
Estimate how much electricity a PV system installed in your school facility could produce
(please look at the solar map), and calculate how large it would be. Repeat the example al74
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ready developed, adapting to your school’s geographic location.
Given data:

5 kW system to install

Modules chosen of 160 watts power each

Dimension of each module: 2 square metres
Glossary
Semi-conductor: a semi-conductor is a substance, usually a solid chemical element or compound, that can conduct electricity (electrical conductivity) intermediately between metals
(conductors) and insulators (no conductors). It conducts under some conditions but not others,
making it a good medium for the control of electrical current.
Photosensitivity: is the amount to which an object reacts upon receiving photons (solar radiation), especially visible light.
Direct current (or DC electricity): is the continuous movement of electrons from an area of
negative (−) charges to an area of positive (+) charges through a conducting material such as a
metal wire.
Direct current was supplanted by alternating current (AC) for common commercial power in the
late 1880s because it was then uneconomical to transform it into the high voltages needed for
long-distance transmission. Techniques developed in the 1960s overcame this obstacle, and direct current is now transmitted over very long distances, though it must ordinarily be converted
into alternating current for final distribution.
References
de Francisco G. A. et al. Energías Renovables para el desarrollo, (Renewable Energies for
Development), Cooperación Internacional, Thomson-Paraninfo, Madrid, 2007.
Web links
http://www.epia.org
http://www.soda-is.com/eng/index.html
http://re.jrc.ec.europa.eu/pvgis/
http://www.pvsunrise.eu/Pictures.asp
Key points:

One of the most important sources of renewable energy is solar energy, whose
source is simply the sun; it is available for free, it is inexhaustible and can be
used in different ways.

We have many options for using solar energy at home, at school and in buildings in general. The three main ways are: passive heat, solar thermal and photovoltaic energy.
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


PV cells are generally made from Crystalline Silicon, in three main ways: from
thin slices cut from a single crystal of silicon (monocrystalline) or from a block
of silicon crystals (polycrystalline), or mixing silicon with others semiconductor materials (amorphous); This is the most common technology representing about 90% of the market today.
A typical commercial PV cell with a surface area of 16 cm² will produce about
2 watts peak power only. However hundreds of cells composing a PV module
will get an interesting electrical generation and have a power output from 10
watts to 300 watts, depending on the technology used – even more if several
modules are connected together (called arrays).
The amount of electricity that a PV system can produce depends mainly on
three factors: the amount of sun energy that reaches the location; the position
and inclination of the modules and their technology.
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7 Exercise - Monitoring Energy Consumption - Home/school facilities Energy
Audit
Grade Level: Secondary
Subject areas: Sciences, Mathematics, Economics, Social studies, Language, Art
Methodology
In this activity, students will apply the energy conservation measures they have learned about
from the “Handbook on Buildings” to perform a comprehensive energy audit of the school or
home building.
The following activity should be performed step by step, following the 6 steps below and the further activity variations suggested, although each step works/is worthwhile as an individual separate exercise.
Tables and formats are suggested for each step, although further tables, figures and data, photos
and graphic representations can be used.
The entire work activity can be performed with:

Pen/paper, and/or

PC (all tables and calculator sheets are available in Excel format on the IUSES web
page and DVD multimedia).
The students can work individually, in pairs or in small groups to work out their energy consumptions and find some energy saving solutions.
Goal(s)
To perform an energy audit, as the first step in assessing how much energy a building consumes
and in evaluating what measures you can take to make it more energy efficient. (You can perform a simple energy audit yourself, or have a professional energy auditor carry out a more thorough audit.)

To estimate energy requirements/consumptions of both electrical and thermal appliances;

To calculate energy costs;

To understand CO2 related emissions and how to calculate them;

To take action to reduce energy loss and consumption.
Summary
1st step – Checking all sources of energy consumption (Appliances – Lighting – Heating and
Cooling)
2nd step – Register and calculate the consumption
2a – Electricity consumption
2b – Fuel consumption
3rd step – Graphic representation
4th step – Calculating CO2 (equivalent) emissions
5th step – Building inspection
6th step – Make recommendation for savings
* Supplementary Step – Variations and combination with other activities:
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1st step
Checking all sources of energy consumption (Appliances – Lighting – Heating and Cooling)
Make an inventory of all energy consumer appliances you can find in your school or home. This
can be done (using tables like those below) following two main criteria:

checking room by room (gymnasium, refectory, classroom – kitchen, bathroom, living
room, etc.); and

checking by type of consumption charge (electric and electronic appliances, lighting, etc.).
Divide them between Electricity and Fuel fired (natural gas, fuel oil, coal, wood) equipments.
Check list Electrical Equipment (Appliances – Lighting)
Room/Space
Name of Appliance
Type (Lighting;
Electric, Electronic
appliance)
Check list Fuel-fired Equipment (Heating-Cooling, etc.)
Room/Space
Name of Appliance
Type
(Space heating
and cooling;
Water heating;
Cooking; etc.)
Fuel type
(natural gas,
oil, etc.)
Extend the lists as you need.
2nd step
Register and calculate the consumption
2a – Electricity consumption
Make a comprehensive list of all electrical appliances (in your home or school), then register
their power consumption (wattage) and estimate for how long they are used (amount of time
each one is on).
The students may ask their parents or teachers about the use of appliances that the students do
not use themselves and together estimate the hours of use. In a case where it is not possible to
find the wattage plate on a given appliance, then use the figures shown in the Handbook or in the
example below.
Then calculate the amount electricity consumption by multiplying the wattage of each appliance
by the number of hours used. Energy used (kilowatt hours) = Power (kilowatts) x Time (hours).
Finally, calculate the cost of the electricity consumption by multiplying consumption by the
price of a unit of electricity (as located in the electricity bill). Cost (€) = €/kWh × kWh.
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Register and calculate the electricity consumption
Name:
Subject of measurement:
Place/Location:
Hours of use per W eek
1
CHARGE
Lighting
Incandescent light bulb 40W
Incandescent light bulb 60W
Incandescent light bulb 75W
Incandescent light bulb 100W
Fluorescent lam p 13W
Fluorescent lam p 17W
Fluorescent lam p 20W
Fluorescent lam p 32W
Fluorescent lam p 40W
Ele ctric Appliances
Air conditioner (room)
Air conditioner
Fa n (table )
Fa n (ce iling)
Clothes Iron
W ate r heate r (50 litre)
Motor or pum p
Clothes w ashe r
Dishw asher
Refrigerator
Free zer
Hair dryer
Clothes dryer
Blender
Mix er
Microw a ve oven
Juicer / sque ezer
Toaster
Vacuum cleaner
Coffe e m aker
Fryer
Electric bla nket
Dehumidifier
Aqua rium
Electronic Applia nces
Personal compute r + monitor
Radio (stereo)
Te levision
VHS
La p top
Equipo de sonido completo
Ninte ndo
CD playe r
Ex tra ctor
Range consumptions
Untill 200 kW h
Between 201 and 1100 kW h
More than 1101 kW h
Nº of
Charge
2
3
De m and
Factor
4
40
60
75
100
13
17
20
32
40
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
800
2000
200
50
1000
1500
0,7
0,7
0
0
0
0
0
0
0
0
Pow e r (W )
600
1500
200
100
1000
2500
600
200
800
50
700
1200
1000
1200
200
800
1000
140
150
120
60
50
300
5
30
500
10
Electricity Price
(Residential):
20 c€/kW h
15 c€/kW h
12 c€/kW h
79
0,9
0,9
0,3
0,4
Hours
pe r day
5
Days of
us e X
We e k
6
Hours pe r
w eek 7 =
5 x 6
0,6
0,6
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0,9
1
1
1
0,9
1
1
0,9
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Wh
pe r
We e k
2x 3x 4
x 7
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
8 TOTAL W h x W eek:
0
Number of W ee ks a Month = 30/7=
4,3
9 W h x Month = 7 x 4,3
0
Transform ing to kW h x Month = 9 /1000
0,00
Total electricity
Sub-total:
consumption cost:
200
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Demand Factor: since many appliances have a range of settings (for example, the volume on a
radio, the temperature selected on an air conditioner), the actual amount of power consumed depends on the setting used at any one time. It means that if an appliance is not running at its maximum wattage (for example not max air conditioning temperature) the electricity consumed not
exactly equals power per time but less. Thus it is used a so called “demand factor” which is a
number by multiplying with and depends on the tipe or use of the appliance. Obviously, factor
equals 1 means the appliance runs always at its maximum wattage, while less than 1 do not. In
the table are reported the tipical Demand Factor for each appliance.
2b – Fuel consumption
The object of this exercise is to convert fuel consumption into kWh, in order to better understand
these kinds of consumption and make comparisons with electricity consumption.
In order to obtain the amount of fuel consumption, it is easier to register them directly by looking
at bills or by asking parents or teachers.
This is because, in contrast to the procedure followed for electricity consumption (step 2a), it is
quite complicated to calculate fuel energy consumption of equipment starting from their own
power (commonly expressed by CV, kcal, therms, etc.).
Transform the consumption (amount of fuel: kg – m³ for natural gas – litres for fuel oil) into
kilowatts by using the following conversion factor table (valid for the most common fuels used
in Europe).
(Available the Excel Calculator data sheet)
Fuel Consumptions
Energy content of selected fuels for end use — Conversion Table
Name:
Subject of measurement:
Place/Location:
Conve rting fue l type s to kW h (1)
Fue l Type
Amount consum e d
(pe r month)
Calculated on a Net Calorific Value basis
Units Units
Na tura l Ga s (2)
kg
Liquefied petroleum gas
(Butane/Propane)
kg
ha rd coa l
kg
Ga soil
kg
W ood (25 % humidity)
Pe lle ts/w ood bricks
m³
litre
X
Conve rsion fa ctor (1)
(kW h pe r unit)
×
13,1 kW h/kg
7,85 kW h/m³
0
×
12,78 kW h/kg
7,65 kW h/l
0
9,87 kW h/l
0
×
6,65 kW h/kg
×
11,75 kW h/kg
kg
×
3,83 kW h/kg
kg
×
4,67 kW h/kg
litre
Tota l kW h
0
0
0
TOTAL
(Source: DIRECTIVE 2006/32/EC of 5 April 2006 on energy end-us e efficiency and energy s ervices )
(1): Mem ber States m ay apply other values depending on the type and quality of fuel m os t us ed in the res pective Mem ber
State.
(2) 93 % m ethane.
80
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3rd Step
Graphic representation
Group all energy charges and appliances detected (now you have all of them in terms of kWh) by
summarized group, as in the table below. Convert the consumption (kWh) into percentage (%).
Then draw a pie chart to show graphically how the energy consumption is shared in your school/
home.
Fill in the pie chart by using the Excel application or by painting the empty chart manually.
Share of Energy Consumption
(Example)
Consumption Sub-groups /
Ene rgy Se rvice
Consumption Pe rcenta ge
(kW h)
(%)
300
100
380
125
100
255
234
57
30
1581
Spa ce heating & cooling
W ater he ating
Lighting
Cooking
Refrige ra tion
Electric Applia nce s
Electronic Appliances
Standby / ghost pow er
Othe r
Total
18,98%
6,33%
24,04%
7,91%
6,33%
16,13%
14,80%
3,61%
1,90%
Pie Chart of Energy Consumption
1,90%
3,61%
18,98%
14,80%
Space heating & cooling
Water heating
Lighting
6,33%
Cooking
Refrigeration
Electric Appliances
16,13%
Electronic Appliances
Standby / ghost power
24,04%
6,33%
Other
7,91%
Manual Chart
81
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4th step
Calculating CO2 (equivalent) emissions
The objective of this exercise is to calculate approximately the Green House Gas (GHG) Emissions related to your energy consumptions.
The most important GHG is the CO2, which represents the great majority, from a quantity point
of view. While the concept of “CO2 equivalent” means including the other GHGs, such as Methane (CH4) and Nitrous Oxide (N2O), they represent only a small amount compared with just
CO2.
In the table below, the “emissions factors” of a range of fuels (the ones used for heating in the
residential and tertiary sectors) are shown, as well as the emission factor of the electricity taken
by the public grid.
Emission factor = Quantity of emissions per unit of energy (Joule or kWh) or per unit of mass
(kg, m³, litre).
In the case of CO2 only, factors for different mass units are given, in order to simplify calculation and to allow the insertion of Energy Consumption expressed by the units available to you.
For CO2 Equivalent, only the Energy input in kWh is allowed.
Note that:
The emission factor of Electricity depends on the Electricity Mix of each country (that is, the
composition of different kinds of energy sources used for electricity production), and may vary
yearly and for each country.
Emission factors of Fuels: An accurate estimation of emissions (mainly for CH4 and N2O) depends on combustion conditions, technology, and the emission control policy, as well as fuel
characteristics. Therefore, the average and most common factors have been considered here.
How to do the exercise:
1. Insert your energy consumptions by using the Unit you have available.
2. Multiply by the related emission factor. For example:
if your energy consumptions are expressed by kg of coal, multiply by 1.9220 to obtain CO2
emissions only;
if they are expressed by kWh of natural gas, multiply by 0.2019 to obtain CO2 emissions
only, and by 0.2178 to obtain CO2 equivalent;
if all energy consumptions are expressed by kWh, obtained thanks to the previous 2b exercise, just multiply by the factors in the two columns of CO2 and CO2 equivalent per
kWh. (Note that the Excel calculator uses the last one multiplied as default.)
3. Observe your total emissions by remembering that, in graphic terms, one Ton of CO2 approximately equals one swimming pool of 10 metres wide, 25 metres long and 2 metres deep.
82
83
Energy Consumption
--2,6479
2,9026
1,9220
3,2740
0,5108
0,2019
0,2271
0,3459
0,2786
X
X
X
X
X
X
Kg of
fuel
kWh
X
--3,8976
4,8457
-----
litre of fuel
-----
---
--3,7827
m³ of
fuel
kg of CO2 per different units as follows:
96100
77400
63100
--56100
TJ
Emissions Factors for selected fuels for End Use
TOTAL
0,3470
0,2800
0,2440
0,5387
0,2178
per kWh
kg of CO2 equivalent (1)
kg of
CO2 equivalen
0
0
0
0
0
0
0
kg of
CO2
0
0
0
0
0
0
0
Emissions
References:
– Eggleston, S., Buendia, L., Miwa, K., Ngara, T. and Tanabe, K., Eds., 2006. “2006 IPCC Guidelines for National Greenhouse Inventories. Volume 2: Energy”,
IPCC National Greenhouse Gas Inventories Programme, Institute for Global Environmental Strategies (IGES), Hamaya, Japan.
– For Net Calorific Values: “DIRECTIVE 2006/32/EC of 5 April 2006 on energy end-use efficiency and energy services”.
CO2 Equivalent includes other GHG emissions, such as CH4 (Methane) and N2O (Nitrous Oxide). An accurate estimation of CH4 and N2O
emissions depends on combustion conditions, technology, and the emission control policy, as well as fuel characteristics. Therefore, an average
factor has been considered here and only for CO2 eq. per kWh as energy input.
Public Electricity
Natural Gas
Liquefield Petroleum
Gas (LPG)
Coal
Gasoil (for boiler)
Other Fuels
Energy Type
Insert here
your consumptions
(Available the Excel Calculator data sheet)
Calculating CO2 (equivalent) emissions
CONVERT ENERGY CONSUMPTION INTO CO2 (equivalent)
IUSES — building handbook
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5 th step
Building inspection...Check your building
This step will show you problems which, if solved, may save you significant amounts of money
over time. During the checking, you can pinpoint where your house or school is losing energy.
An audit also determines the efficiency of your home’s heating and cooling systems and shows
you ways to conserve hot water and electricity.
You can easily conduct a home energy audit yourself. When auditing your home, keep a checklist of areas you have inspected and problems you found. This list will help you prioritize your
energy-efficiency upgrades.
Student assignment: Identify whatever helps or hurts energy conservation in a specific building.
Look for "bad elements" that waste energy and money.
Energy Audit Data Sheet
Degree of implementation
Basic Standards
Nothing
Starting
Implementin
g
Lights and Equipment
When adequate light is available from the sun, or when rooms are unoccupied, all
lights are to be turned OFF.
X
Are lights in passage places (i.e., corridors, toilet, etc.) turned OFF when not in
use ?
X
Are electronic ballasts installed to provide the proper starting and operating electrical condition to power lamps?
X
Computer monitors are either turned OFF, or computers are put into Sleep mode
when not in use.
Computer peripherals such as printers, scanners and other electronic equipment are
to be turned OFF when not in use.
X
X
All outside lights are to be turned OFF during daylight hours.
All outside lights are to be turned OFF at night.
X
X
Portable heaters may only be used as a short-term emergency measure. Principals
must authorize their use in these circumstances.
Small “bar” refrigerators are prohibited unless there are compelling reasons for their
use in exceptional circumstances.
X
X
Only the most energy-efficient equipment is purchased (e.g., Highest Energy Label
and Energy Star).
An equipment consolidation program is implemented to ensure that energy is not
wasted by using more equipment than is necessary (e.g., unplugging and/or removing unnecessary refrigerators and reducing the number of computer printers through
networking).
X
X
Are there lighting Control Systems such as: power stabilizers of lighting depending
on the sunlight (light sensors) or automatic switch while a space is occupied by
someone (Occupancy Motion Sensors), or simply timers.
A cleaning lighting fixtures programme is in practice.
X
X
Are walls and ceiling lights enough in colour to reflect light well?
Incandescent lightings has been removed and replaced with compact fluorescent.
Etc. ..Extend the list...
84
X
X
Extensively
IUSES — building handbook
Degree of implementation
Nothing
Basic Standards
Heating and Cooling
Windows and curtains are closed at the end of the school day.
Space around vents on walls or window sills is kept free of obstruction.
Extensively
X
X
Internal gym doors are kept closed.
Mechanical equipment is checked regularly and problems are reported promptly.
X
Are insulating drapes or other tight window treatments such as framed shades in
place?
Have all heating boilers been checked and are well insulated?
Exhaust fans off if not needed (gym, restrooms).
When it is hot in a room, is opening windows done rather than regulating radiators
by thermostat valves?
Implementin
g
X
Doors to the outside of the building are not left open longer than necessary.
Are hot water faucets free from drips?
Are the ceilings insulated? (ask the headmaster or professor)
Is heating and cooling equipment (ducts, radiators, grilles) blocked by curtain, furniture, blankets, etc.?
Starting
X
X
X
X
X
X
X
Is there effective weather stripping on doors?
X
Etc. ..Extend the list...
General Awareness and Management
Are there posters that favour energy savings spread around the school facilities
(such as “Do not leave the lights on”, or “Close the door to avoid heat losses”, etc.)?
X
Is student participation promoted through Workshops or Awards?
Has a sort of Energy or Environment Board been created, composed of students and
teachers engaged in fostering best energy practice?
X
X
Etc. ..Extend the list...
The above table includes just a limited list of items to be checked, so that it is recommended to
extend it freely according to your facility characteristics.
85
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6th step
Make recommendations for energy saving
As the final step, after having collected data and information about energy performance for your
school or home, it is time to take action and establish energy-saving measures.
This step aims at drawing up a list of recommendations, behavioural and technical, which will
help you to reduce energy consumption and losses. Obviously, the range of changes proposed
should derive from energy weakness and faults detected by the previous building inspection (step
5); with the objective of improving and solving them. Consequently, numerous measures could
be put in place.
Here the task is to consider only the most important measures or the ones which you consider to
be technically or economically feasible for your case.
Please follow these steps:
a.
Propose a range of measures/changes/interventions (freely extend the list);
b.
Calculate the energy savings (estimate approximately the potential percentage of
savings for each measure with respect to the electricity and/or fuel consumption);
c.
Estimate the costs of actions and the pay-back period (search for the market price
of the action proposed; then divide it by the economic savings to know the payback period);
d.
Calculate the CO2 avoided (use the same emission factors previously used in the
CO2 table – exercise step 5).
The following table includes just a few examples of recommended measures. Please freely extend the list according to your facility’s characteristics.

Insert here your consumptions and the proper data for emissions and prices, according
to the type of Fuel used and local energy Prices. For emission factors and units, use the
same data as in the previous CO2 emission sheet.

Then use these data for proceeding to the calculations required for filling in the table
below.
Example
Unit
Ene rgy Type
Ele ctr icity (fr om grid)
Cons um pti
Em is s ion
on pe r
Factor s
m onth
(k g CO²e q/.....)
Price
€/.....
kW h
3500
0,54
0,19
kW h
litre
kg
litre
3200
0,22
0,20
Fue ls for He ating
Natural Gas
Liquef ied Petroleum Gas (Butane, Propane)
Coal
Gasoil
Other Fuels
0
0
0
0
Example:
If you are considering changing “light bulbs”, the type of saving is “Electricity”:
1.
energy saving affects Electricity = 15% (estimated % saving) of 3.500 kWh (your electricity consumption);
2.
CO2 emissions avoided are to be calculated = multiplying electricity saved (525 kWh)
by the emission factor of the electricity (0.54 kg of CO2/kWh – “it changes for any
country”);
3.
Economic savings = electricity saved (525 kWh) x electricity price (0.19 €/kWh –
“search for local price”).
If you are considering “installing double-glazed windows”, it is a “heating measure”, consequently:
86
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1.
2.
3.
the percentage of savings is calculated over the amount of Fuel used (10% x 30.000
kWh);
the emission factor of CO2 emissions is the Natural Gas one (0.2 kg/kWh);
the economic savings are calculated with the Price of Natural Gas.
Type
of
Energ
y
MEASURES PROPOSED
The
rma
l
Heating
Improving thermal
insulation of the walls
Installation of double
glass windows
Apply weatherstripping and caulking
around doors
Installation of selfclosing systems for
external doors
Install Thermoregulation systems
(thermostatic valves
and timers)
Keep windows and
doors closed when
heating or cooling
systems are operating
Do not use drapes or
curtains to cover the
windows during winter days (solar gain)
And Close them at the
end of the school day
(avoiding heat loss)
In Winter set temperature at 15ºC for bathroom and corridors,
while 20-21ºC for
rooms
Do not leave open
Doors to the outside
of the building longer
than necessary.
Start the heating system (boiler) one hour
before school activity
begins and turn off at
elast one hour before
the end
Do not block heating
and cooling equipments (ducts, radiators, grilles) by curtain, furniture, blankets, etc.
Type
Behavioral/
Technica
l
% of
Savings
Energy
Savings
T
30%
960,00
CO2 avoided kg/
month
Economic
Savings
(€/
month)
Cost of
the
Action
(€)
Pay Back
period
(months)
Recommendations about
feasibility
209
192
50.000
260,4
In the case of
rehabilitation
T
15%
480,00
105
96
26.000
270,8
Whenever the
existing windows are single
pane and not
recently installed
T
20%
640,00
139
128
1.500
11,7
Always
T
5%
160,00
35
32
2.000
62,5
Always
T
5%
160,00
35
32
1.500
46,9
Always
B
5%
160,00
35
32
0
0,0
Always
B
5%
160,00
35
32
0
0,0
Always
B
5%
160,00
35
32
0
0,0
Always, unless
a partucularly
strong cold
season
B
2%
64,00
14
13
0
0,0
Always
B
5%
160,00
35
32
0
0,0
Always, unless
a strong cold
season
B
2%
64,00
14
13
0
0,0
Always
87
IUSES — building handbook
Type
of
Energ
y
MEASURES PROPOSED
Electr
icity
Lightings and Equipments
Replace Incandescent lighting with
low consumption
compact fluorescent ones
Install lightings
Control Systems
(light sensors, occupancy motion
sensors or timers)
especially in corredors and bathrooms.
Install electronic
ballasts to fluorescent lamps
Use Power Strips.
Plug home electronics and office
equipment into
power strip with an
on/off switch.
When adequate
light is available
from the sun, or
when rooms are
unoccupied all
lights are to be
turned OFF.
Put in place a frequent a programme
for cleaning luminaries
All lights, including
the outside ones,
are to be turned off
at night
Computer monitors
are either turned
OFF, or computers
are put into Sleep
mode when not in
use.
Type
Behavioral/ Technical
T
% of
Savings
15%
Energy
Savings
525,00
CO2 avoided kg/
month
283
Economic
Savings
(€/
month)
100
Cost of
the
Action
(€)
800
Pay Back
period
(months)
Recommendations about
feasibility
8,0
Always, wherever the frequency of
switch on and
off is not so
frequent
T
10%
350,00
189
67
500
7,5
Always, mainly
in corredors,
bathrooms and
places where
switch on/off is
do frequent
T
6%
210,00
113
40
700
17,5
Always
T
2%
70,00
38
13
200
15,0
Always
B
4%
140,00
75
27
0
0,0
Always
B
2%
70,00
38
13
0
0,0
Always
B
10%
350,00
189
67
0
0,0
Always
B
3%
105,00
57
20
0
0,0
Always
88
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Variations and combination with other activities:
“Energy label detectives” – Investigation of the difference between the energy consumption of
the best and worst available product in the shops.
“Standby power in my home/school” – Investigation of the standby power consumption at home
or school.
Carbon footprint: Get the pupils to calculate their family’s carbon footprint by using an on-line
calculator such as www.carbonfootprint.com.
Get really creative: Ask the pupils to imagine life without electricity. Try one day without electricity. What did our forefathers do before electricity was discovered? Even looking 100 years
ago can be an eye-opener for children.
A bit of History: Make a large timeline showing approximately when certain electrical appliances were introduced. Start with the light-bulb.
Introduction of a competitive element: Challenge! Can you save 500 Watt in a week? Get the
students to plan how to do this, preferably with their parents/teachers help.
89
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90