Home Energy Audits: Testing Your Home's Efficiency

Maximum thermal performance leads to a comfortable, energy-efficient home.

If you asked homeowners whether their home had optimal thermal performance, you'd likely get a blank stare. But ask them whether their den is cold or the windows are drafty, and you're likely to get a far more animated response.

Achieving thermal performance means effectively bundling a home up against the elements, so that it stays as warm as possible in winter and as cool in summer, without maxing out the heating and cooling equipment. This will lead to a comfortable, energy efficient home.

But without testing a home it's impossible to know the level of thermal performance until the walls and ceiling are closed up and you or your clients are living in the home. By then it will be very expensive to tear apart what you just constructed and fix it.

The best practice for ensuring adequate thermal performance for a home's building envelope (its roof, walls and foundation) is to perform three different tests. These tests will reveal problem areas, so that you can find and fix them.

1) A blower door test measures the airtightness of the home. A blower door is a powerful, large fan that is temporarily mounted in a house door to measure the leakiness of the house and to help find the location of the leaks. Modern blower doors have variable speed fans so that the pressure in the house can be adjusted, and they also have door-mounting frames so that the fan can be sealed tightly into the door jamb. In order to measure the leakiness of the house, the blower door measures both the air flow through the fan and the pressure difference between the house inside and outside.

2) Low-emissivity window checkers are handheld devices that are placed on the interior pane of a window to detect if a window has a low-emissivity coating. Low-emissivity coatings help to reduce the heat transmitted through the pane, which contributes to the interior comfort of the home. Sometimes odd-shaped windows such as transom windows above doors and the small panes of a stained glass window will not have low- emissivity coatings. If you have a contract with a window manufacturer that guarantees every window has a low-emissivity coating, this test will detect windows without the coating, and the manufacturer will be obligated to replace them.

For more information about energy efficient windows, visit the Department of Energy's Energy Savers website.

3) Infrared, or IR, cameras take infrared images of a house. Pictures taken from the outside detect hot spots, while ones taken from the inside detect cold spots. The images also indicate the temperatures in certain areas. This test is particularly useful in detecting insulation issues and air leakage within a home.

Each of these tests requires specialized contractors and consultants to conduct them. To find a contractor, contact the National Association of Energy Service Companies (NAESCO).

Before contracting with an energy auditing company, you should take the following steps:

  • Get at least five references, and contact all five. Ask if they were satisfied with the work.
  • Call the Better Business Bureau and ask about any complaints against the company.
  • Make sure the auditor uses a calibrated blower door.
  • Make sure they do thermographic inspections using infrared cameras or contract another company to conduct one.

Complete information on testing homes, including audits you can do on your own, can be found at the Department of Energy's Energy Savers website.

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