Download Cooling guidelines PL

Efficient and innovative cooling and air conditioning in buildings
Use of ground heat exchangers
Guidebook for building owners and administrators
The sole responsibility for the content of this publication lies with the authors. It does not represent the opinion of the
Community. The European Commission is not responsible for any use that may be of the information contained therein.
1 Introduction
Dear Reader
We hope that this Guidebook will reach you and rise your interest up.
Whom are we addressing?
We are addressing millions of building owners, administrators and developers. To those, who already
possess buildings and are going to retrofit them to upgrade the buildings operation standard and also
to those who will construct their buildings – residential, service and, public service ones. We can
realise that it is not always possible to rationally apply innovative technologies for air conditioning –
certainly not everyone will make a decision to undertake such steps. However, there are still more and
more applications not only implemented by enthusiastic people but also by those who make economic
decisions.
Why do we encourage to use energy efficient and innovative cooling technologies in buildings
Our common ecological awareness is rising up. We are still more and more convinced that it is our
obligation to the future generations, to secure sustainable development of the world, countries, towns
and villages.
Resources of fossil fuels: hard coal, natural gas, crude oil etc. will be available in the next 40-50 years
regarding hydrocarbon fuels, and 200 – 300 years – regarding hard coal. However, we are using still
more and more energy. Its consumption for air conditioning purposes in our houses, offices and service places is still increasing. Additional forecasts issued by different independent institutions show
that this demand will continue to increase, especially in the developing countries in Central Europe.
Even though, any activities oriented at mitigation of energy demand for air conditioning still have a
very low priority level and are known to a small group of experts and even smaller group of building
administrators and owners. Through this publication and through involving ourselves into implementing process of the COOLREGION project, we would like to change this situation.
Which technologies and equipment in buildings
This guidebook focuses on these technologies and equipment that from the technical viewpoint could
be implemented in buildings and from the economic viewpoint promise to be economically efficient
already now or in the future practice.
2 What to consider during the designing process
Energy prices are continuously increasing. This situation enforces necessity to save fuels and to reduce energy consumption and stimulates rational use what directly turns into climate protection effects.
In order to make any buildng an optimal one it is necessary to find its correct location. Selection of a
piece of ground for future construction shall be dictated by a possibility to erect a building oriented to
South (acceptable are deviations up to a dozen or so degrees). It is important to have a building site
wide enough to functionally design the building inside, especially the residential compartments in a
way to assure daylight from the Southern direction, while auxiliary compartments (bathroom, kitchen,
wardrobe, technical roms, staircase, corridors) should be located from the Northern side.
The building should be of comprehensive shape. Evergy wall corner and angle creates a place in
which a thermal bridge may appear. Another question is that a complicated building costs much more
in terms of thermal enveloping. The less area for insulation, the better.
An important part of passive and energy saving buildings is its South face wall. This wall creates in
practice and independent system dedicated to shaddowing in summer and acquiring as much as possible yield from thermal sun radiation during the winter months. In order to meet those two assumptions that seem to be mutually excluning, some design issues need to be resolved. First, it is necessary to correctly install the shaddowing elements in a way that excludes creating of thermal briges. It
is also a problematic issue to install any elements to walls having a thick insulation layer. Beside overglazing, shaddowing system and insulation, also solar collectors can be used as well as photovoltaic
batteries.
Any external walls and faces of the building, elevations, roof, windows or flooplaced on the ground
shall have a very low heat transfer coefficients. All of them shall be 2-3 times lower than in cases of
standard constructions, respectively (according to the present regulations for new buildings).
Requirements under Ordinance
Requirements under Ordinanceof the Ministry of Infrastructure of 14
of the Ministry of Infrastructure, on
February 2008 r. on detail
Technical conditions to be fulfilled
Scope and form of
by buildings and its locations
Energy audit
Type of barrier
standard for a passive building
wsp. przenikania
wsp. przenikania
wsp. przenikania
oprór cieplny
oprór cieplny
ciepła
ciepła
ciepła
2.
2.
2.
2.
2.
2.
U [W/m K]
R [m K/W]
U [W/m K]
R [m K/W]
U [W/m K]
R [m K/W]
3,33
4,00
0,30
0,25
6,67
0,15
?
1,25
4,00
0,80
0,25
0,25
0,22
0,15
4,00
4,50
6,67
?
oprór cieplny
External wall T
External wall T
Roof / ceiling
o
> 16 C
o
i < 16 C
i
windo
0,59
1,70
0,59
1,70
1,25
External doors
0,38
2,60
bw
bw
0,91
?
?
0,80
1,10
bw – no requirements
A typical feture that differs passive buildings from the traditional ones is the way of heating or cooling.
This is because passive buildings are not equipped with heating or cooling installations that can usually be found in typical buildings. Cooling and heating is usually carried out along with mechanical
ventilating. One should remember that a building should be designed in a way that makes it possible
to reduce its basic heating demand to a value of about 15kWh/m2 per year. An important role in reducing energy demand can be dedicated to the use of renewable and alternative energy resources, such
as heat pumps or ground heat exchangers.
Przeszklenie o
współczynniku
przenikania
ciepła U≤0,8
W/m 2K
Szczelne przegrody
zewnętrzne o
współczynniku
przenikania ciepła
U<0,15 W/m2K
Wywiew
Wylot
zurzytego
powietrza
Nawiew
Zyski cieplne z
promieniowania
słonecznego
Rekuperator
Nagrzewnica
Wlot
świeżego
powietrza
Filtr
Gruntowy wymiennik ciepła
Summarising the above, the following conclusions can be drawn about features to characterise buildings:
1)
Demand for energy necessary for heating of one square meter of internal area, during a single
heating season shal be below 15 kWh, which is equivalent to combustionof 3 kg of hard coal or
1,5 litter of heating oil.
2)
Passive solar yields cover 40% of heat demand.
3)
Correctly insulating, low-emission window glazing (3 layers or with a special membrane).
4)
Wll insulating window frames.
5)
Walls having high insulating properties.
6)
Mitigation to an absolute minimum of thermal bridges.
7)
Low permeability fr air into and out from the building through the external walls.
8)
Compact, not complicated shape of the building.
9)
Mechanical ventilation that removes moisture better that the traditional convective one.
10)
Heat recovery from ventilation air.
11)
No conventional separate hetaing / cooling systems. Heating and cooling are performed by injection of hot or cold air along with mechanical ventilation.
12)
Optionally – recovery of heat and chill from the ground. External air blowed into the building
should be pre-heated or pre-cooled in a ground heat exchanger.
13)
Optionally – recovery and storage of heat from solar heat radiation (solar collectors, transparent
insulation, etc.).
14)
Optionally – recovery of heat ‘hidden’ in the ventilation air (heat pump air-to-air).
15)
Use of shaddings (leave trees, roofs, roller blinds) from the south wall in to order to minimize
solar radiation penetration into the building.
3 Use of innovative cooling technologies
In case of high thermal insulation properties of the external surfaces, that is usual for passive
buildings, the role of ventilation increases significantly, although it often either missunderstood or
underestimated. Without an efficient mechanical ventilation, heat recovery by means of a heat
recuperator and ‘hidden’ heat recovery by means fo heat pump or ground heat exchanger would not
be possible.
Fresh air intaken for ventilation of rooms mas pass through a piping system placed under the ground
or through a gravel bed in order to become pre-heated. This is a so-called ground heat exchanger
which is a common solution used in passive buildings. Ground heat exchanger makes it possible to
recover clean energy from the ground. This is a verry efficient kind of equipment (energy consumption
derives only from air flow resistance / pressure drop). Furthermore – construction of a ground heat
exchanger is relatively simple and cheap – this can be a „home-made” device. Despite numerous
advantages of such solution it cannot be used with gravity ventilation, commonly used in buildings.
Such heat exchanger can only be used in buildings with mechanical ventilation.
Design of ground heat exchanger (GHE) includes a natural bed (layer) of clean, flushed gravel placed
in the ground. Air flowing through the gravel (depending on the year season) in the sumer is cooled
and dried, in the winter is heated and saturated with moisture and all over a year is filtered by removal
of dust and bacteria. Direct contact of the bed with the surrounding ground enables a fast regenaration
of the bed temperature.
Parameters of the exhaust air downstream the gravel bed are characterised with very slow deviations
in time, that can be only detected in a several-month lasting cycles. In practice, during one month
these deviations are hard to be noticed. This is a positive effect because the result of this phenomena
is that any day-by-day appearing changes in air temperetaure are levelized during a day period and
during consecutive days, even if rapid changes in ambient temperature take place.
In cases when the ambient temprerature increases rapidly, that occure sometimes in winter and intermedium periods, as well as during rapid drops of temperature in summer, owing to the fact that the
exchangers respond with a certain delay, it may happen that during certain periods of time, from the
ventilation viewpoint, the parapeters of air downstream the bed are worse that the ambient air parameters. Correctly operated automatic control system shoule assure intake of the air from the better
source.
In autumn and by the end of summer, the air temperature downstream the bed is higher than during
the winter and spring months. In the turn of August and September this temperature may reach as
much as 22°C at ambient temperature of +32°C. In turn of February and March ma be -2°C at. ambient -20°C, especially with strong frost „attack” in January and February. A big inertia of the exchanger
results in the fact that climat Quarters of the bed temperature are shift in relation to the climate seasons. This shift reaches about two months.
Possible configurations of GHE:
In the places where surface ground water appears, a GHE may be located in different configurations
in relation to the ground surface.
a) The GHE may be entirely hidden under the ground surface (only the air intake head stays over the
ground).
b) The GHE is partly submerged. A part of the exchanger is located under the ground and the remaining part is elevated above the ground surface.
c) The GHE beside a ground slope. One or two walls of the exchanger belong to this slope.
d) (not illustrated) Bottom of the GHE lies on the ground. The insulation inserted several dozen centimeters into the ground and on the slope surface makes it possible to elevate ground isothermal
lines above its surface, into the exchanger. In order to obtain comparable thermal effect the GHE
capacity shall be increased.
Calculations of energy effects to come from using a Ground Heat Exchanger for building ventilation
and air conditioning.
In order to determine heating and cooling capacity of a ground heat exchanger, a simplified method
can be applied for designing. This is the IGSPA (The International Grodnu Source Heat Pump Association) method.
Following this method, the exchanger capacity is calculated from the below formula:
Qw =
Vn ⋅ ρ ⋅ c p ⋅ (t1 − t e )
3,6
[W ],
where:
Qw – exchanger capacity
Vn – amount of introduced ventilation air
ρ – air density downstream the GHE
cp – specific heat of the air downstream the GHE
t1 – air temperature downstream the GHE
te – ambient air temperature.
Average ambient air temperatures are pre-assumed according to the Polish Standard PN-82/B-02403
while temperatures downstream the ground heat exchanger can be assumed following the example
specification of a ventilation system coupled with a GHE, as in the Figure below.
Symbols:
tp - indoor temperature in the building
tm - temperature of the air mix or downstream the recuperator (efficiency up to 70%)
tz - tw - outdoor and indoor temperatures
tgw - temperature at the GHE outlet
tnoz tnoc - temperature of in-blown air.
Necessary amount of the air can be determined on the basis of air replacement multiplicity or from the
necessary amount of air per capita.
Number of ventilation air replacements per hour is called ‘air replacement multiplicity’. This value depends not only on cubature of rooms but also on the place and intensity of air pollution. Experimental
values gained for different types of rooms / compartments vary in a wide range. It can be assumed
that e.g. for office rooms the hourly air replacement intensity shall reach a value of about 1, in classrooms – 2 and residential rooms – 0,5. By multiplying the replacement multiplicity for a chosen type of
room by its cubature the amount of ventilation air can be determined.
Another way to determine the ventilation air amount is to base it upon the number of persons who use
the rooms. The Polish National Standard PN-83/B-03430 on ventilation in residential and public service buildings defines amounts of ventilation air injected from the outdoor, per capita. Typical values
are as follows:
ƒ
20 m3/h for every person present in a room
ƒ
30 m3/h per every person in a room in case of rooms in which smoking is allowed.
Basic properties of GHE
1. Simple design of GHE, use of available and cheap materials makes it possible to manufacture a
GHE, generally in any place and any conditions. This entails a possibility of common use of this equipment for ventilation, air conditioning and thermal ventilation.
2. Utilisation in a simple way of the natural energy resources of the ground at small depth for cooling
and heating of the ventilation air stream
3. Use of e ground heat exchanger is purely a way to use renewable energy resource. An investor
who makes a decision to construct such equipment may apply for a grant or a preference investment
loan from The Bank for Environment Protection or from the National or Voivodeship Fund for Environment Protection and Water Management.
4. Use of a GHE may generate additional savings related to automation of air conditioning equipment
because due to the inertia of a GHE the parameters of air at the GHE outlet do not depend (to a large
extent) on the changes in outdoor air properties at the GHE intake. Outlet air parameters are relatively
stable in a long time horizon and do not require ongoing control.
5. Air parameters at the gravel bed outlet are subject to very slow variations in the function of time and
are noticable only over a few-months lasting cycle. During a period of one month such changes are
practically neglicible. This phenomenon gives a convenient result because any daily rapid changes of
outdor air are levelised as well on a daily basis as for longer periods of time, when rapid increase or
drop of ambient temperature can be observed.
6. High capacity and low operation costs of a GHE make it possible to use only the outdoor air for
ventilation – without necessity of blending it with used air through recirculation. Up to date, the largest
GHE in Poland has total capacity of 137 thousand m3/hour.
7. Only the costs of air transportation across the gravel bed are caried (pressure drom of ca 100 Pa)
without costs of its heating or cooling.
8. A GHE assures to entirely cover chill demand during the summer period. The relation between energy input (fan) and energy yield reaches an average value of 1:15.
9. Air stream from the GHE that enters the recuperators (even at winter extreme conditions with –20oC
outdoor) does not cause freezing of the cross heat exchnger because the recuperator inlet temperature is close to 0oC or is positive.
10. Use of GHE in the winter period makes it possible to gain up to 50% of ventilation heat from the
ground.
11. Recirculation or use of a recuperator allows to gain further amounts of heat, up to 20-30%.
12. Average maximum temperature difference of the air upstream and downstream a GHE in summer
10÷12°C, and in winter 18÷20°C refers to extreme outdoor air temperatures reaching +32°C i -20°C
respectively. The average thermal effect of the gravel bed equals 1kW/m3 and during the summer and
winter peak conditions it reaches even up to 2kW per 1m3 of the bed.
13. Best energy effects are obtained during the extreme weather conditions, i.e. for low outdoor temperatures in winter and high outdoor temperatures in summer. Any harmful peaks are „cut” out.
14. Dowstream the GHE the air humidity is reduced in the summer period, e.g. from 15,2 down to 12,7
g/kg, while during winter air humidity increases.
4 Good existing examples
Energy efficient buildings complex of the EXBUD Company, with
cubature of 96.000 m3, incorporates many energy efficient solutions
of heating system based on ground heat exchangers and heat
pumps. Energy gained from the ground through pipels either tubular
heat exchangers and from waste heat. Further heat savings result
from automatic control of ventilation parameters and air replacement
and temperature in some rooms and selected periods of time.
Energy efficient installation systems include recovery of additional
energy from outdoor renewable sources, by means of using:
ƒ tubeless ground heat and substance exchangers,
ƒ tubular ground heat exchnger;
An unique in Poland renewable energy resource are the ground heat
exchangers use in this building complex for pre-heating of fresh ventilation air in winter and its cooling in summer. These exchanger are
displaced around the complex at a small depth, under the grassbeds.
The accumulative – transferring bed a layer of fine granite has been
used. The relation between input capacity (fan motor power) and the
energy effects (yield) reaches 1:30. Most of the buildings in this Centre has been equipped with such tubeless exchangers. In the hotel
building a ground tubular exchanger has been installed in which
ventilation air is pre-heated in winter and cooled in summer as the
result of its flow through the piping system positioned under the
ground at the depth of 1,5 to 2,0 meters.
A sinle-family building using alternative energy sources for cooling
and air conditioning.
The building is located on concrete cross-shaped foundations, between which two Ground Heat Exchangers filled with flushed river
gravel.
The building is well enveloped in terms of thermal insulation.
Walls: k < 0,30 [W/m2K],
Roof: k < 0,25 [W/m2K],
Windows: k = 1,1 [W/m2K],
In addition to that, a heat pump (air-to-water) operates in the building.
Cooling of the outdoor air intaken into the buildings goes in the result
of air flow through a bed of gravel located in the ground. Owing to
use of flushed river gravel and owing to positioning the fireplace inthe central part of the building, the objects presents perfect accumulative properties. The building has been occupied since 2003 and
according to the reports by its owner the object assures high comfort
of use with very low expences for energy carriers.
5 Further information
We hope that this Guidebook will reach you and rise your interest up with energy efficiency and
innovative technologies of cooling.
For detail information and data please visit:
www.eplan.info.pl/coolregion
and
www.taniaklima.pl
TANIA KLIMAtyzacja gruntowa i ogrzewanie
ul. Graniczna 49 j
Poland 41-408 Mysłowice
tel:[+48] (32) 201 61 68
6 Literature / sources
1) Joanna Rucińska
- “Zastosowanie uproszczonej metody projektowania gruntowego
wymiennika ciepła do oceny jego efektywności energetycznej”, Politechnika Warszawska,
“Building Physics in Theory and Practise”
2) Sławomir Kurpaska, Hubert Latała, Kazimierz Rutkowski - „Analiza wydajności cieplnej
gruntowego wymiennika ciepła w instalacji wykorzystującej pompę ciepła”, Inżynieria Rolnicza
11/2006
3) Sławomir Pasierb, Mariusz Bogacki, Arkadiusz Osicki, Jerzy Wojtulewicz – „Odnawialne Źródła
Energii. Efektywne wykorzystanie w budynkach. Finansowanie przedsięwzięć”, poradnik FEWE
4) Witold Piecha „Opłacalna wymiana”, Magazyn Instalatora 02/2006