What is an energy audit?

The dictionary definition of an audit is a methodical and through examination and review . Therefore, an energy audit examines the energy use of a particular location, such as a building. It evaluates the efficiency of all building and process systems that use energy.






What are the purposes of an energy audit?

An energy audit can be complex, lengthy and expensive or relatively simple, quick and cheap: it basically depends on the budget allocated. At the low end, the audit is really an inspection or overview of energy use in the facility and does not dig at all into details. At the top end, there is almost no limit to what can be done.

Audits suitable for homes and small business

• a walkthrough of the facility comparison of energy consumption data from utility bills with typical usage for similar facilities identification of obvious energy-saving changes

Audits suitable for medium-sized organisations

• a walkthrough of the facility comparison of energy consumption data from utility bills with typical usage for similar facilities

• onsite measurements analysis of equipment, systems, operational characteristics

• detailed identification of energysaving changes

Audits suitable for large organisations

• expanded detail in evaluation, analysis and testing

• computer simulation of current situation and effects of possible changes

These notes will deal with the low level audit. Higher level audits require more substantial skills and training than can be allowed for here.

Conducting the audit

Like any process, an audit is best done with information before action. In this case, find out as much as you can about the facility and its operation, be it a home or small business, before you do the walkthrough. If you go on site without really knowing the background, you will be wasting your time and the client’s money.

The type of audit consists of three steps as shown in Figure 1.


Collect background information

FIGURE 1 Steps in a low-level audit

Step 1. Collecting background information

The type of information you need before you go onsite to do the walkthrough is what you would obtain by email or phone conversation. It would include:

• the type of building (construction materials)

• a floor plan

You probably wouldn’t require detailed energy consumption data from utility bills at this stage, but you could ask the client to collect as many as possible, so that they are available when you arrive for the walkthrough.




Add to the list above – other pieces of useful information about a facility’s energy use.


Conduct facility walkthrough


Analyse results and information and make recommendations

As with any audit, being organised for the walkthrough is essential, so you should go armed with a checklist or list of questions to ask. These questions will be different for different types of buildings, eg house, café, small factory, shop. Some of these questions could be answered over the phone (or by email) but are better checked visually. An example would be “is the building insulated?”. The occupier may not know, but will give you an answer anyway, which may be wrong.

Step 2. The walk-through

This is where you actually set foot inside the building with the intention of examining specific aspects of the energy consumption of the facility. Unless you are very familiar with the building, it is essential that you are accompanied on your inspection by someone who is able to answer questions that arise. If it is a specialist facility like a small factory, make sure the person knows how the equipment works.

Try to anticipate basic hand tools and test equipment you will need to perform a thorough inspection. Always bring a flashlight, straight and Phillips head screwdrivers and a pair of pliers. A tool belt will help keep your hands free. Other tools could include:

Allen wrenches calculator camera clipboard crescent wrench flashlight knife light meter pliers tape measure thermometer

Talk with building occupants as you tour the facility. They often provide valuable information from a different point of view.

Impressions regarding comfort, lighting

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levels, occupancy patterns and hours of operation can lead to additional ideas for energy conservation opportunities.

One aspect often forgotten is that building usage fluctuates during the day/week/month/year. If you have the time and the budget, visit again during an off-peak time. It may reveal energy consumed without purpose, and an easy way of making immediate savings.

Before you leave, take a moment to make sure you have seen everything you need to see. You may not have the time to come back. Particularly ensure that you have the electricity and gas bills for at least the last year, and preferably more.

Step 3. Analysis and report

Now it is time for you to look at the data and the answers to your questions and consider your observations. Where can energy consumption be reduced? When considering where savings can be made, remember one key point: The best results will be obtained by examining the big energy-consuming processes.

Making energy savings anywhere is good, but it would be a waste of valuable time to concentrate your attentions on areas where a very small proportion of the facility’s energy consumption is.

By way of example, you could cut energy consumption by half for a device that uses 10 W of electricity, but this would make less overall difference than a 1% reduction in a process using 10kW. This is not to say that you should ignore the small savings, but they should be lower down the priority list.

If you can identify what the actual minimum energy requirement for the facility (known as the base load) is, you might be able to identify where energy is being wasted when not required, eg air conditioning on at weekends, ovens running overnight on full heat.

The report

If you are required to write a formal report, it could use the following structure, though it is hardly the only way to approach such a report.

1. Executive Summary

This needs to summarise the findings and list the recommendations (or at least the highest priority ones) in one page.

2. Building Information

This section provides a general background of the facility, the mechanical systems, and operational profile. A description of the building envelope, age and construction history, operating schedules, number of employees, occupancy patterns, and a discussion of the operation and maintenance program should be included.

The building information section should also contain a floor plan, selected photos of the facility and mechanical systems, a description of energy types used in the plant, and a description of the primary mechanical systems and controls.

You might think that the client will already know all this but you might be surprised. This might be the first time that such information has been assemble din the same place.

3. Consumption data

This will depend on how much information you have been provided with, but if you have more than a year’s worth of data, then you could graph it; less than this will be best served in a table.

4. Summary of current situation

Essentially this tells the client how well they are doing now, putting into context the recommendations in the next section.

Include any benchmarking information you have been able to gain.

5. Recommendations

This is the valuable part of the document for the client. It will provide a prioritised list of the actions that can be taken to reduce energy use, and should include where possible, cost and savings estimates.

See also Fact Sheet 5: Benchmarking &

Fact Sheet 6: Ideas for Energy Saving

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