Download Energy Audit

Gestão de Energia
Energy audits
Carlos A. Santos Silva
Professor Associado Convidado
Cátedra WS – Energia
Departamento de Física
[email protected]
Outlook
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•
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Energy Audit
Energy Services
Energy Efficiency Measures
Measurement and Verification
ENERGY AUDIT
3
Overall objectives
•
Detailed analysis of the energy use in a certain equipment, activity,
installation , building, campus:
–
Where energy is used
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When energy is used
–
How energy is used
• Through an audit it is possible to:
– identify/model the required energy services
– Design a solution to improve the energy use and supply
• Equipment replacement, process change, user behaviour change
Energy Audit Phases
• Preparing and Planning
• Facility inspection
• Field Work
• Data analysis
• Energy audit reporting
• Energy Action Plan
Action Plan
• An action plan is a strategy plan to increase
the energy efficiency of the facility
– It describes the solutions
– It describes the efficiency objectives
– It describes the implementation plan
• This plan results from the energy audit
PREPARATION AND PLANNING
7
Tasks
• Collect data regarding energy use
– Energy bills (3 or more years if available)
• Collect data regarding building envelope and equipment's
– Location and weather data
– Building description (blueprints, bill of materials, etc.)
– Characteristics of the main equipment's
– Functional organization
• Preliminary data analysis
– Find any awkward result
Preliminary visit
• Visit together with the facility manager to see
how the facility operates
• Collect missing data (if available)
• Observe the building envelope
• Identify “low-hanging fruit” savings
FACILITY CHARACTERIZATION
10
Objective
• Detailed analysis of the collected data
– Evaluate energy consumption baseline (normalize
climate data)
– Prepare energy balance
– Identify energy services
• Characterize equipment's performance
Main Equipments
• Heating and cooling
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Hot water and steam boilers
Chillers and cooling towers
Ait treatment units
Ventilation units
Pumps and pipes
Air conditioning units
Air conditioning controllers
• Hot Water
– Tankers
• Lighting
– Lights
– Ballasts
– Controllers
Other Equipments
• Elevators and other mechanical transportation
systems
• Specific equipment's of the building
– Monitors in hospitals, TVs in restaurants
• Refrigeration equipment's in kitchens , laundries,
pools
• Energy generation systems (solar, co-generation)
• The efficiency of every heat generation system
should be verified
Field Work Plan
• With the collected data and the
characterization of the facility, prepare the
field work:
– The list of equipments that will be measured
– The list of equipments that needs to be used for
measurement
– The measuring procedure (one point measure,
long data collection)
– Interviews to be done to complete information
FIELD WORK
15
Main activities
• Measure energy consumption of main sectors/equipments
– Productive systems, hot water, heating and ventilation
– Identify lack of maintenance
• Verify electric installations
• Verify HVAC and lighting controllers
• Continuous monitoring or main consumption points of energy to obtain
load diagrams
– One day
– One week
Complementary activities
• Complementary measurements to collect
information
– Room temperatures
– Room luminance
• Characterize schedule of main equipments
(interviews, observations)
• Characterize the envelope in detail and how
users interact with it (interviews, observations)
• Characterize utilization patterns
Audit Equipment
Thermometer
Thermo-hygrometer
Thermography
Lux meter
Network analysers
Current Clamp
DATA ANALYSIS
19
Objectives
• Disaggregation of energy consumption by energy
services
– Complete energy balance
• Develop load diagrams
– Daily, weekly and if possible annual evolution
• Evaluate energy indicators, specific consumptions
– Deviation form disaggregation and indicators should
provide hints regarding energy efficiency measures
Activities
• Evaluate efficiency of the equipments and installations and
estimate savings from equipment replacement, process change or
behaviour change or installation of generation equipments
• Evaluate technical feasibility of doing equipment replacement,
process change of behaviour change
• Due the economic evaluation of implementing such measures
• Determine facility energy class
Energy balance
• The energy balance disaggregation should be in an annual
basis
– Consider average consumption of the last 2/ 3 years, suing
information from energy bills
– Consider the information gathered in the audit
• Equipment's use schedule
• Equipment's characterization
• Equipment's measurements
• Simulation (software)
Simulation
• Objective is to obtain the energy consumption
considering the utilization, the equipments,
the envelope
• The model should be adjusted to the field
measurements
• The calibrated simulation will enable:
– Testing different energy efficiency measures
Energy bills
• Evaluate the average consumption across the
year
– With more than one year, the influence of
weather of activity may be filtered
• Verify correctness of tariffs
• Evolution of used power
– Impact of equipments or activity change
AUDIT REPORT & ACTION PLAN
25
Objective
•
Describe the energy demand of the installation and the costs
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Describe the equipment status
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Identify energy efficiency measures, the investment and its potential payback
– Substitution or retrofit of equipment
– Use of more efficient controllers
– Installation of energy management systems
– Introduction of renewable resources generation
•
Identify upcoming changes in regulations that may impact on the current energy
use
Action Plan
• From the different measures proposed in the
energy audit, identify an implementation plan
– Investment plan
– Schedule
• Low cost measures should be the first to be
implemented
• The return of investment period should be the indicator
used to prioritize the measures in the plan
• This should be done closely with the energy manager
and the board
Gestão de Energia
Energy services
Carlos A. Santos Silva
Professor Associado Convidado
Cátedra WS – Energia
Departamento de Física
[email protected]
Outlook
•
Space Heating and Cooling
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Thermal balance
Heat transfer
Internal gains
Solar gains
Climate
Comfort
Insulation
Hot water
Cooking
Food Conservation
Lighting
Entertainment
Work
House keeping
Communication
SPACE HEATING (AND COOLING)
30
Thermal Balance (1)
• Applying the 1st law of
thermodynamics
– Balance between all the
gains and losses
• Solar (S)
• Internal(I)
• Conduction, convection and
radiation through envelope (T)
• Air mass balance/ventilation
(V)
Thermal balance (2)
Internal gains
Solar gains
Ventilation
Envelope
Winter
+
+
-
-
Summer
+
+
-/+
-/+
(-) Losses
(+) Gains
Thermal balance – closed system (3)
• 1st law of thermodynamics
– Internal energy variation
∆𝑈 = 𝑄 − 𝑊
∆𝑈 = 𝑚𝐶𝑣 ∆𝑇
• Mass includes air, walls, furniture, etc…
– Heat
• Transfer through windows, walls, et…
• Generation and absorption
– Occupants
– Appliances (work consumption)
𝑚𝐶𝑣 ∆𝑇=𝑄𝑖𝑛 − 𝑄𝑜𝑢𝑡 + 𝑄𝑔𝑒𝑟
𝑄 = 𝑄𝑖𝑛 − 𝑄𝑜𝑢𝑡
𝑄𝑔𝑒𝑟
(𝑄𝑔𝑒𝑟 ≅ −𝑊)
Thermal balance – open system (4)
• 1st law of thermodynamics
∆𝐸 = 𝑄 − 𝑊 +
𝐸𝑖𝑛 - 𝐸𝑜𝑢𝑡
– Ventilation
– Air leakages (infiltrations)
𝑄−𝑊 =
𝑚𝑜𝑢𝑡 ℎ𝑜𝑢𝑡 +
𝑄−𝑊 =
𝑉𝑜𝑢𝑡 2
2
+ 𝑔𝑧𝑜𝑢𝑡 - 𝑚𝑖𝑛 ℎ𝑖𝑛 +
𝑚𝑜𝑢𝑡 ℎ𝑜𝑢𝑡 - 𝑚𝑖𝑛 ℎ𝑖𝑛
𝑉𝑖𝑛 2
2
+ 𝑔𝑧𝑖𝑛
Heat transfer gains
• Conduction
• Convection
• Radiation
𝑄 = 𝑘𝐴
𝑇1 − 𝑇2
𝐿
𝑄 = ℎ𝐴 𝑇1 − 𝑇2
4
𝑄 = 𝜀𝜎𝐴 𝑇 1 − 𝑇 2
4
Internal gains (𝑄𝑔𝑒𝑟 )
• Electric appliances
– Computers
• Heat generation in power sources, processor
– Lighting
• Radiation and convection
– Occupants
• Radiation, convection, latent heat (water vapour)
We do not consider here the heat generation from radiators, fireplaces, AC
Energy generated by occupants
Solar gains
• Heat Exchange with
the sun
– Direct (sunny days)
– Diffuse (cloudy days)
• Usually evaluated
using the RTS (radiant
time series method)
Air exchanges and leakages
• Air Exchange between the interior and the
exterior originates changes in the internal
energy (and thus temperature)
𝑄 = 𝑚 ℎ𝑒𝑥𝑡 − ℎ𝑖𝑛𝑡 (𝐽/𝑠)
𝛿ℎ
𝑐𝑝 =
𝛿𝑇
𝑝
𝑄 = 𝑚 𝐶𝑝 𝑇𝑒𝑥𝑡 − 𝑇𝑖𝑛𝑡 (𝐽/𝑠)
Dynamic simulation
• It allows to evaluate all
heat exchanges and
calculates heating and
cooling needs
Design Builder
Open Studio
40
THE INFLUENCE OF CLIMATE
41
Degree Days
• Simple and direct method (though incomplete) to
characterize the climate of a certain region
– It measures the product between the number of days and the
number of degrees that the interior temperature is lower
(heating) or higher (cooling) than a certain comfort temperature
• Heating degree days (HDD)
• Cooling degree days (CDD)
𝐻𝐷𝐷 𝑇𝑐𝑜𝑛𝑓 =
1
24
8760
𝑚𝑎𝑥 𝑇𝑐𝑜𝑛𝑓 − 𝑇𝑒𝑥𝑡 ,𝑖 , 0
𝑖=1
𝐶𝐷𝐷 𝑇𝑐𝑜𝑛𝑓 =
1
24
8760
𝑚𝑎𝑥 𝑇𝑒𝑥𝑡 ,𝑖 −𝑇𝑐𝑜𝑛𝑓 , 0
𝑖=1
HDD and CDD in Europe
43
THERMAL COMFORT
44
Comfort temperature
“mind state that expresses satisfaction about the
thermal environment”
• Human comfort depends on the ability to control
the body temperature between 36 and 37ºC
• It depends on the balance between heat
exchange
– It is not only about air temperature
• It depends on the humidity (evaporation/transpiration)
– It depends on the activity, clothes, etc…
Comfort conditions
• Temperature: 20 to 27ºC
• Relative humidity: 30 to 60%
INSULATION
47
Thermal and air leakage insulation
Thermal bridges
• It describes the disruption of
the thermal insulation due
to the existence of a
material with high
conductivity
• They can represent up to
20% losses
Green roofs and facades
• Adds width (L) with a fairly good insulation
– k: 0.18 a 0.41 W/mK
– Concrete roof k=1.4 W/mK
• Has impact on radiation and convection
through latent heat
HOT WATER
51
Hot Water
• Water used for
– Showers
– Washing (dishes, clothes, house cleaning)
• Important Variables
• Litters of water
• Final temperature (Hot)
• Initial temperature (Cold)
• Energy
∆𝑈 = 𝑚𝐶𝑝 ∆𝑇
Water usage
• Reducing water usage reduces energy water
consumption
Water Temperature
• The Final Temperature has two conflicting constraints
– Skin scalding (5s at 60ºC)
– Bacterial Contamination (e.g. Legionella)
• The European Guidelines for Control and Prevention of Travel Associated
Legionnaires’ Disease recommend that hot water should be stored at 60
°C (140 °F) and distributed such that a temperature of at least 50
°C (122 °F) and preferably 55 °C (131 °F) is achieved within one minute at
points of use
• The Initial Temperature
– Depends on the ambient temperature
Pipes losses
Typical values in Portugal
LIGHTING
56
The importance of lighting
• The way we “feel” in a certain environment
depends on the light
Transparent vs. Opaque spaces
• Glazed facades gives spaces a lighter
appearance
– Daylight availability (+)
– Heating by solar radiation (+)
– Conduction exchanges (+)
– Visual comfort problems (-)
Light design (natural + artificial)
• Light impacts directly on
– Visual Comfort
– Productivity
– Energy Consumption
• These objectives are sometimes conflicting
Natural vs Artificial light
Measuring “Light”
• Luminous Flux – quantity of light emitted by a
luminous source in all possible directions (lm)
• Luminous Efficacy – Ration between the luminous
flux and the power of the source (lm/W)
• Luminous intensity – Luminous flux per unit of
solid angle (cd)
• Illuminance – ration of luminous flux by the area
of incidence (lux=lm/m2)
• Luminance – ration between luminous intensity
emitted in a given direction and the apparent
area of the luminous
Visual Comfort
• Visual comfort is a subjective impression related to
quantity, distribution and quality of light.
• Visual comfort is reached when objects can be seen
clearly, without tiredness and in a pleasantly colored
environment
– The level of illumination of the visual task;
– The luminous distribution in the space (light repartition,
luminance ratio and embarrassingly shading);
– The sight towards outside;
– The colour rendering and the colour of the light source;
– The absence of glare.
Illuminance
• Type of space
• Activity
Glare
• Visual conditions in which there is excessive
contrast or an inappropriate distribution of light
sources that disturbs the observer or limits the
ability to distinguish details and objects (CIE)
• Difficulty to see in the presence of bright light
(natural or artificial)
– caused by a significant ratio of luminance between the
task and the glare source.
– Depends on the angle between the task and the glare
source and eye adaptation
General characteristics of artificial light
Artificial light efficiency
Artificial light colour
Luminaire cleaning
ELECTRIC SERVICES
69
Electric Power
• Not all the power is useful
Power in AC (P=UI)
•
Inductance and capacitance elements cause
energy flow changes (AC)
–
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Capacitance introduces a 90º lead between
current and voltage
Inductance introduces a 90º lag between
current and voltage
R
C
L
RC
RL
Electricity bill (low voltage)
Electricity bill (medium voltage)
Food Conservation
Refrigerator Labelling
75
Working
• Personal computer
– CPU
• awake 120 W
• asleep = 30 W
– Monitor
• awake 150 W
• asleep = 30 W
– Laptop = 50 W
Working (2)
• Printers
– Inkjet
– Laser
• Scanner
• Copy
Communication
• Router
• DataShow
Gestão de Energia
Energy efficient measures
Carlos A. Santos Silva
Professor Associado Convidado
Cátedra WS – Energia
Departamento de Física
[email protected]
Gestão de Energia
Measure and Verification
Carlos A. Santos Silva
Professor Associado Convidado
Cátedra WS – Energia
Departamento de Física
[email protected]
Outlook
• Measure & Verification
• IPMVP
– Introduction
– Definitions
– Framework
MEASURE AND VERIFICATION
83
Definition
• Process to quantify the savings associated with the implementation
of energy efficiency measures
– Measures energy, not the cost
– It is necessary to evaluate economic savings
– It is based in the application of a methodology
• International Performance Measurement and Verification Protocol (IPMVP)
• ASHRAE Guideline 14:Measurement of Energy and Demand Savings
• eeMeasure
IPMVP application
Energy Conservation Measure (ECM)
•
An activity or set of activities designed to increase the energy efficiency of a facility, system or
piece of equipment.
–
ECMs may also conserve energy without changing efficiency.
•
Several ECM's may be carried out in a facility at one time, each with a different thrust.
•
An ECM may involve one or more of:
•
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physical changes to facility equipment,
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revisions to operating and maintenance procedures,
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software changes,
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or new means of training or managing users of the space or operations and maintenance staff.
An ECM may be applied as a retrofit to an existing system or facility, or as a modification to a design
before construction of a new system or facility.
Savings
• The reduction in energy use or cost.
– Physical savings may be expressed as avoided energy use
or normalized savings
– Monetary savings may be expressed analogously as “cost
avoidance” or “normalized cost savings”
• Savings, as used in IPMVP, are not the simple
difference between baseline and reporting period
utility bills or metered quantities.
Normalized Savings
•
The reduction in energy use or cost that occurred in the reporting period, relative
to what would have occurred if the facility had been equipped and operated as it
was in the baseline period but under a normal set of conditions.
•
These normal conditions may be a long term average, or those of any other chosen
period of time, other than the reporting period.
•
Normal conditions may also be set as those prevailing during the baseline period,
especially if they were used as the basis for predicting savings.
•
If conditions are those of the reporting period, the term avoided energy use or just
savings, is used instead of normalized savings.
Estimate
• A process of determining a parameter used in a savings calculation
through methods other than measuring it in the baseline and reporting
periods.
• These methods may range from:
– arbitrary assumptions
– engineering estimates derived from manufacturer’s rating of equipment
performance.
– Equipment performance tests that are not made in the place where they are
used during the reporting period are estimates, for purposes of adherence
with IPMVP.
Baseline Period
• The period of time chosen to represent operation of the facility or system
before implementation of an ECM.
• This period may be as short as the time required for an instantaneous
measurement of a constant quantity, or long enough to reflect one full
operating cycle of a system or facility with variable operations.
– Baseline Energy: The energy use occurring during the baseline period without
adjustments
– Adjusted-baseline energy: The energy use of the baseline period, adjusted to
a different set of operating conditions.
Reporting Period
•
The period of time following implementation of an ECM when savings reports
adhere to IPMVP.
•
This period may be :
– as short as the time for an instantaneous measurement of a constant quantity;
– long enough to reflect all normal operating modes of a system or facility with variable
operations;
– the length of the financial payback period for an investment;
–
the duration of a performance measurement period under an energy performance contract;
– or indefinite.
Adjustments
•
Routine Adjustments: The calculations shown in the M&V Plan to account for changes in selected
independent variables within the measurement boundary since the baseline period.
–
Independent Variable: A parameter that is expected to change regularly and have a measurable impact on
the energy use of a system or facility.
•
Non-Routine Adjustments: The individually engineered calculations to account for changes in static
factors within the measurement boundary since the baseline period.
–
When non-routine adjustments are applied to the baseline energy they are sometimes called just “baseline
adjustments”
•
Baseline Adjustments: The non-routine adjustments arising during the reporting period from
changes in any energy governing characteristic of the facility within the measurement boundary,
except the named independent variables used for routine adjustments.
Measurement Boundary
• A notional boundary drawn around equipment and/or
systems to segregate those which are relevant to
savings determination from those which are not.
• All energy uses of equipment or systems within the
measurement boundary must be measured or
estimated, whether the energy uses are within the
boundary or not
IPMVP FRAMEWORK
94
Savings
Savings =
Baseline-Period Use / Demand
– Reporting-Period Use / Demand
± Routine Adjustments
± Non-Routine Adjustments
M&V Design
• Define a M&V plan (duration, accuracy) according to the available
budget and needs
• Gather relevant energy and operating data from the baseline period
and record them in away that can be accessed in the future
• After the ECM is installed, ensure it has the potential to perform
and achieve savings by conducting operational verification
• Compute and report savings