Building Energy audit-methodology

1. Building Energy Audit-Methodology

2. Introduction
Energy audit is an investigation and detailed analysis of the energy (and water) entering and
leaving a building, and is carried out to pinpoint the areas where there is potential for energy
efficiency measures and savings.
Main aim:
• To identify actions that will lead to savings in energy and costs.
Other aims:
• Reduction in carbon emissions.
• Improved environmental conditions for the occupants of the building.
• The development of a system for recording energy use.
• The development of monitoring and targeting schemes.
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3. Introduction contd..
The energy entering the building comes from a number of sources (oil, coal, gas, electricity, etc.)
and “free” sources, such as solar radiation and people, which supply light and heat.
This energy is used to power: heating equipment, lighting, cooling equipment, fans, pumps, cooking
appliances, refrigerators, appliances (computers, printers, etc.), larger items of machinery, lifts and
escalators, etc.
All this energy is eventually converted to heat and leaves the building via a number of routes:
• Transmission through the building envelope,
• Flue losses
• Infiltration and ventilation losses, etc.
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4. Usually the audit is broadly classified into four categories
 Benchmarking
• Preliminary cost analysis, comparison with similar energy efficiency solutions.
 Preliminary audit (walk-through)
• Available data mostly used for a simple analysis of energy use and performance of the technical
systems.
• It is not time consuming and results are rather generic and include simple economic calculations.
 Detailed audit (Diagnostic audit)
• Detailed data and information on all technical systems is required. Detailed measurements and
data inventory is needed for each system (pumps, fans, compressors, etc.).
• The economic calculations should cover at least NPV, IRR, Payback period etc.
• The result is list of clearly defined measures that the client should implement in order to improve
the energy efficiency of the building.
 Investment-grade audit
• Includes complete technical and economic analysis at the investment level.
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Methodology

5. Methodology contd…
An energy audit report is divided into four number of phases
• Pre-survey information and data collection
• Analysis of the data collected
• Formulation of energy-saving solutions
• Reporting of results
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6. Pre-Survey Data Collection
Introductory meeting with the administration and head of maintenance services
Data collection
The collected information may include:
• Electricity/gas/oil/solid fuel/water utility bills
• Plans/elevations/design of the building (incl. building services systems)
• Location of the building (climate)
• Information on the controls and building management system (BMS)
• Information on the structure of the building (U-values, materials, etc.)
• Information on the building’s purpose, hours of work and operation.
Bills going back number of years (at least 3) will enable long-term trends in energy usage.
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7. Walk-Through Survey
Walk-through survey will provide much additional information which cannot be obtained from the
plans.
There are often changes made (extensions, new ventilation plant, additional insulation, etc.)
The condition of the building should also be noted
• Cleanliness of light fittings.
• Collect all the technical characteristics of the domestic hot water (DHW) system including
distribution system and the medium.
• Listing all the technical characteristics of all three systems, the distribution part and the
medium, the cooling/ventilation elements such as convectors, fans, etc.
Standard of maintenance (maintenance plans).
Any specific problems such as broken valves, leaks, missing lagging and other defects should be
noted.
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8. Walk-Through Survey Contd…
Conditions in the building may be measured as well, various hand-held devices are available
nowadays: for temperature, humidity, lighting level, etc. (provide only indication of the conditions
prevailing at the time of the survey)
Interviews with building managers, engineers, caretakers and others can provide useful reliable
evidence and better understanding of the operation of the building.
Spot reading can be useful in identifying potential problems (problems with temperature control,
etc.)
Control issues may also be identified:
• Do users have manual override for heating controls?
• Are there open windows immediately above working radiators?
• Can the user adjust light levels?
• Where are the light switches?
• Are computers switched off at night?
• Is there manual control of ventilation?
• Are fans switched on at night for night cooling
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9. Analysis of The Data Collected
The form and extent of the analysis depends on the number of factors:
• The depth of the audit
• The nature of the building
• The degree to which the energy consumption data can be disaggregated into end uses
• The needs of the client
For complex buildings it is worth to model the performance using proprietary software for simple
steady-state heat loss calculations or detailed hourly simulations of HVAC performance.
Measured or estimated energy consumption should be compared with that of other buildings
having the same function.
• The results of analysis should include at least:
• Analysis of all the energy and water bills and definition of referent energy/water
consumption.
• Model the energy and cost balance.
• Model the balance for each type of energy and water consumer.
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10. Formulation of Energy-Savings Solutions
• The analysis of the data collected should result in the identification of where energy use is high
and where there is waste.
• Such “waste” can be reduced by implementation of no-cost solutions (changes to occupant
behavior, low-tech solution such as adding blinds to the windows) to highly engineered and costly
measures (installation of combined heat and power system, etc.).
• After the suitable means of energy reduction are identified, the estimated savings should be
calculated and their cost effectiveness should be assessed.
• The energy efficiency measures should be calculated according to the referent energy
consumption (real consumption from energy and water bills.
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11. Reporting
The report can be made to the client outlining:
• The present state of the building.
• An analysis of current energy use.
• Identification of areas of waste and where energy can be saved.
• Details of the kinds of intervention which will reduce energy use Details of the savings
possible.
• The cost-effectiveness of the methods recommended.
Measures can be listed in order of preference (lowest cost, shortest payback, highest net present
value, etc.)
List of best options should be presented to management in the form of an energy audit report
List of where you think energy is being wasted, where and how savings could be made.
 Specific recommendations
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12. Sample Problem
A 2BHK residential house in palakol, west Godavari district, Andhra Pradesh is taken for auditing.
Energy bills are around Rs.35000-40000 per year.
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13. Sample Problem Contd…
The average energy consumption of the 2BKH house is about 700KWh per month with major loads like
Air conditioners, Fridge, Geyser and Lightning etc.
ENERGY SAVING PROPOSALS WITH INVESTMENT
Replacing old Air conditioner
It is found that more energy is being consumed due to old Air conditioner in Bed room 2. Working for
8 hours a day it is drawing an energy of 319.8 KWh per month with power rating of 2000KW. If it is
replaced with new 5 star rated one we can have the following benefits.
• Power rating of new Air conditioner 1400W = 1.4KW
• Compressor run time per day 5.33 hours Energy consumption per day 1.4 x 5.33 = 7.462KWh
• Energy consumption per month 7.462 x 30=223.863KWh
• Monthly saving of 319.8-223.863=96KWh
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14. Sample Problem Contd…
• The average cost per unit Rs.8
• Monthly saving 96 x 8 = Rs.768
• Annual saving 768 x 12 = Rs.9216
• A new AC Rs. 35000
• Payback period = 35000/9216 = 3.79
• Therefore the payback period is 3.79 years.
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 Replacing Fluorescent lamps with LEDs
If we replace the 36W fluorescent lamps in closed rooms like Bed rooms and kitchen with 7W LEDs
which is more suitable for closed rooms as it has less beam angle & even exhibit more luminous
intensity than fluorescent lamp apart from being eco-friendly.

15. Sample Problem Contd…
The following outcomes could be observed
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• Energy saving per month 8.19 KWh Saving per year 8.19 x 12 = 98.28 KWh
• Saving in terms of money 98.28 x 8 = Rs.786.24
• Cost of each LED 350
• For 5 LEDs 350 x 5 = Rs.1750
• Therefore the payback period is 2.2 years.

16. Sample Problem Contd…
• Use of Immersion water heater instead of Geyser
• Geyser is used for 1 hour a day and it consumes 3KWh a day.
• per month its usage is 90 KWh.
• Cost per 90 KWh is 90 x 8 = Rs.720
• If we use immersion water heater instead of geyser it will consume 1 KWh for 1 hour usage.
(For the same work) That is per month its usage is 30 KWh.
• We can save up to 60 KWh.
• Cost per 30 KWh is 30 x 8 = Rs.240
• Therefore we can save up to Rs.480/- per month
• Cost of a new Immersion water heater is Rs.1500
• Payback period is 3.12 months.
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17. Sample Problem Contd…
• In synopsis the followings are the main conclusions:
• Replacement of old Air conditioner with a new star rated would cost around 35000/- and it
will pay back in period of 3.79 years, by implementing this we can save up to 96KW per
month i.e. 13.5% of total consumption.
• As mentioned in recommendation 2, it is efficient to replace fluorescent lamp with LED will
save up to 1.2% and its payback period of investment is 2.2 years.
• If they use Immersion water heater instead of Geyser we can prevent power wastage of
60KWh. The cost of a new immersion water heater is 1500 rupees and the payback period
3.12 months. It will save 8.5% of total power.
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18. References
• Electrical Energy Audit in Residential House (sciencedirectassets.com)
• Microsoft Word - BSR-1819217-577 (ijsr.in)
• Hirst E., Berry L. and Soderstr J., 1980. “Review Of Utility Home Energy Audit Programs”
• Mendis N.N.R., 2006. “ENERGY AUDIT: A CASE STUDY” Department of Electrical Engineering
University of Moratuwa Katubedda, Sri Lanka, pp.45-50.
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19. THANK YOU