A home energy audit and what it finds

A home energy audit is the first step toward making a home more efficient. A certified auditor looks at how the house uses energy and where it loses it, then identifies and ranks the improvements.

Audits vary in depth. Some take about an hour. A thorough one takes about four hours, uses specialized equipment and costs more.

What the auditor tests

A thorough audit uses diagnostic tests:

• A house air leakage test. A blower door is a large fan that pulls air out of the house. As it runs, a technician measures how tight the house is and finds the leaks.
• A duct leakage test on the heating and cooling ducts.
• An infrared scan of the house.

The auditor also interviews you about the house, runs safety tests, inspects the heating and cooling equipment and the insulation, and looks for mold and moisture.

The three steps

A full audit has three steps:

1. Test in. The auditor measures the house as it is.
2. Improvements. Qualified contractors install the recommended work.
3. Test out. The auditor measures again to confirm the work did what it should. Not every auditor offers this, so ask.

Who does audits

Auditors are certified through Home Performance with ENERGY STAR, the Residential Energy Services Network (RESNET) and the Building Performance Institute (BPI). Some utilities offer audits too. A professional audit is the most reliable way to find air leaks, which are often hidden.

Paying for it

Many utilities offer rebates on a professional home energy assessment, so ask yours before booking. Households that qualify by income may be able to get an assessment and weatherization work through their state's Weatherization Assistance Program.

Before a full audit

On a windy day you can run your own leak check, with a damp hand held near closed windows and doors. Bring what you find to the visit.

An annotated example

What to do next

Call your utility and ask whether it offers audits or rebates on one. Gather a year of energy bills, and note any rooms that are drafty or hard to heat. When you book, ask whether the audit includes a test-out after the work.