Professional Energy Audits

Professional Energy Audits

Professional energy audits generally go into great detail and can provide insight into energy savings.The energy auditor should do a room-by-room examination of the residence, as well as an examination of past utility bills.

Many professional energy audits will include a blower door depressurization test. Most will also include a thermographic scan.

This video shows a home energy audit being conducted.

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How to buy?
What are my Options?
What do I ask a contractor?

How to buy?

Preparing for an Energy Audit. Before the energy auditor visits your house, make a list of any existing problems such as condensation and uncomfortable or drafty rooms. Have copies or a summary of the home's yearly energy bills. (Your utility can get these for you.) Auditors use this information to establish what to look for during the audit. The auditor first examines the outside of the home to determine the size of the house in square feet, its volume and its features (i.e., wall area, number and size of windows). The auditor then will analyze the residents' behavior:

Is anyone home during working hours?
What is the average thermostat setting for summer and winter?
How many people live here?
Is every room in use?

Your answers may help uncover some simple ways to reduce your household's energy consumption. Walk through your home with the auditors as they work, and ask questions. They may use equipment to detect sources of energy loss, such as blower doors, infrared cameras, furnace efficiency meters, and surface thermometers or spot radiometers.

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What are my Options?

De-pressurization Test. If you are having difficulty locating leaks, you may want to conduct a basic building de-pressurization test:

   1. First, close all exterior doors, windows, and fireplace flues.
   2. Turn off all combustion appliances such as gas burning furnaces and water heaters.
   3. Then turn on all exhaust fans (generally located in the kitchen and bathrooms) or use a large window fan to suck the air out of the rooms.

This test increases the infiltration rate through cracks and leaks, making them easier to detect. You can use incense sticks or your damp hand to locate these leaks. If you use incense sticks, moving air will cause the smoke to waver, and if you use your damp hand, any drafts will feel cool to your hand.

On the outside of your house, inspect all areas where two different building materials meet, including:

All exterior corners
Where siding and chimneys meet
Areas where the foundation and the bottom of exterior brick or siding meet.

You should plug and caulk holes or penetrations for faucets, pipes, electric outlets, and wiring. Look for cracks and holes in the mortar, foundation, and siding, and seal them with the appropriate material. Check the exterior caulking around doors and windows, and see whether exterior storm doors and primary doors seal tightly.

When sealing any home, you must always be aware of the danger of indoor air pollution and combustion appliance "backdrafts." Backdrafting may occur when the various combustion appliances and exhaust fans in the home compete for air. An exhaust fan may overcome the natural chimney draft, pulling the combustion gases back into the living space. This can obviously create a very dangerous and unhealthy situation in the home.

In homes where a fuel is burned (i.e., natural gas, fuel oil, propane, or wood) for heating, be certain an appliance that uses a chimney has an adequate air supply. Generally, one square inch of vent opening is required for each 1,000 Btu of appliance input heat. Heating appliances that are “direct vented” have their own outside air supply and a power exhaust, and do not need additional venting. When in doubt, contact your local utility company, energy professional, or ventilation contractor.

Thermographic Scans. Energy auditors may use thermography—or infrared scanning—to detect thermal defects and air leakage in building envelopes.

How They Work

Thermography measures surface temperatures by using infrared video and still cameras. These tools see light that is in the heat spectrum. Images on the video or film record the temperature variations of the building's skin, ranging from white for warm regions to black for cooler areas. The resulting images help the auditor determine whether insulation is needed. They also serve as a quality control tool, to ensure that insulation has been installed correctly.

A thermographic inspection is either an interior or exterior survey. The energy auditor decides which method would give the best results under certain weather conditions. Interior scans are more common, because warm air escaping from a building does not always move through the walls in a straight line. Heat loss detected in one area of the outside wall might originate at some other location on the inside of the wall. Also, it is harder to detect temperature differences on the outside surface of the building during windy weather. Because of this difficulty, interior surveys are generally more accurate because they benefit from reduced air movement.

Infrared scanning allows energy auditors to check the effectiveness of insulation in a building's construction. The resulting thermograms help auditors determine whether a building needs insulation and where in the building it should go. Because wet insulation conducts heat faster than dry insulation, thermographic scans of roofs can often detect roof leaks.

The energy auditor may use one of several types of infrared sensing devices in an on-site inspection. A spot radiometer (also called a point radiometer) is the simplest. It measures radiation one spot at a time, with a simple meter reading showing the temperature of a given spot. The auditor pans the area with the device and notes the differences in temperature. A thermal line scanner shows radiant temperature viewed along a line. The thermogram shows the line scan superimposed over a picture of the panned area. This process shows temperature variations along the line. The most accurate thermographic inspection device is a thermal imaging camera, which produces a 2-dimensional thermal picture of an area showing heat leakage. Spot radiometers and thermal line scanners do not provide the necessary detail for a complete home energy audit. Infrared film used in a conventional camera is not sensitive enough to detect heat loss.

Preparing for a Thermographic Inspection. To prepare for an interior thermal scan, the homeowner should take steps to ensure an accurate result. This may include moving furniture away from exterior walls and removing drapes. The most accurate thermographic images usually occur when there is a large temperature difference (at least 20°F [14°C]) between inside and outside air temperatures. In northern states, thermographic scans are generally done in the winter. In southern states, however, scans are usually conducted during warm weather with the air conditioner on.

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What do I ask a contractor?

Selecting an Energy Auditor.There are several places where you can locate professional energy auditing services.   Look for auditors who are certified with the Building Performance Institute (BPI).  This website lists certifications of auditors and contractors.  Your state or local government energy or weatherization office may help you identify a local company or organization that performs audits. They may also have information on how to do your own audit. Also check your telephone directory under headings beginning with the word "Energy" for companies that perform residential energy audits. Before contracting with an energy auditing company, you should take the following steps:

Get several references, and contact them. Ask if they were satisfied with the work.
Make sure the energy auditor uses a calibrated blower door.
Make sure they are BPI certified.
Make sure they do thermographic inspections or contract another company to conduct one.

Before getting a professional energy audit it may also be useful to complete the online energy audit. Please click here to start the home online energy audit.

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