Home Energy Audit: What It Includes, Cost and How to Get One

A home energy audit tells you exactly where your house is wasting energy, so you can spend money on the fixes that matter instead of guessing. The U.S. Department of Energy (DOE) calls an assessment the essential first step to lowering energy bills. This guide covers what a professional audit includes, what it costs, how to find a qualified auditor, free and low-cost options, and a do-it-yourself checklist you can start today.

What does a professional home energy audit include?

A professional audit usually includes an interview about your bills and comfort problems, a walk-through of the home, a blower door test to measure air leakage, an infrared scan to find hidden leaks and missing insulation, and checks on heating, cooling and safety. You should get a written report with prioritized recommendations.

DOE describes an in-depth assessment in three phases:

1. Test in. The auditor interviews you, runs safety and air leakage tests, inspects equipment and insulation, and looks for signs of mold and moisture.
2. Upgrades. Qualified contractors install the recommended improvements.
3. Test out. Safety tests and visual checks confirm the work was done well. Not every auditor offers this step, so ask.

The blower door test

The blower door test measures how airtight your house is. A powerful fan is mounted in a panel that fits an exterior door frame. It pulls air out of the house, lowering the pressure inside, so outdoor air rushes in through every gap. The auditor then uses a smoke pencil to find the leaks.

DOE advises making sure the auditor uses a calibrated blower door connected to a pressure gauge called a manometer. That gives an exact measurement of air leakage. A blower door without that gauge can spot leaks but cannot tell you how much air your house is losing.

The infrared (thermographic) scan

An infrared camera shows temperature differences along walls, ceilings, windows and doors. Warmer and cooler areas show up as lighter and darker patches. When the scan is done while the blower door runs, air leaks appear as dark streaks, which makes them easy to find. It can also show wall cavities where insulation is missing or has settled.

Duct leakage test

Some auditors also use a duct blower, a smaller fan connected to your ductwork, to measure how much air leaks from the ducts. That matters: ENERGY STAR estimates that about 20% to 30% of the air moving through a typical duct system is lost through leaks, holes and poor connections.

Safety and combustion testing

During the audit, DOE notes the assessor may inspect your heating and cooling systems, test for natural gas leaks and check that the home is properly ventilated. If you have gas, oil or propane appliances, ask whether the auditor does combustion safety testing. That matters most after air sealing, because a tighter house can change how appliances vent.

How much does a home energy audit cost?

DOE estimates a professional home energy assessment costs approximately $250 to $600 or more. The price depends on the size of your home, how many tests are done and where you live. Many utilities offer audits free or at a reduced cost, and some contractors discount the audit if you hire them for the upgrades.

Because prices vary so much by region, get at least three written quotes and compare what each one includes. Here is how the common options compare:

Is there still a tax credit for an audit?

Not for 2026. The federal Energy Efficient Home Improvement Credit (25C) allowed up to $150 for a home energy audit, but it does not apply to property placed in service after December 31, 2025. An audit done in 2025 may still qualify on your 2025 tax return, so check with a tax professional. Our guide to energy tax credits in 2026 explains what changed and why.

How do you find a qualified energy auditor?

Look for an auditor certified by the Building Performance Institute (BPI) or the Residential Energy Services Network (RESNET). DOE also suggests asking your electric or gas utility and your state or local energy or weatherization office, which often keep lists of approved auditors tied to their rebate programs.

Questions to ask before you book:

1. Are you certified by BPI, RESNET or a state program?
2. Will you use a calibrated blower door, and will you give me the leakage number?
3. Do you use an infrared camera?
4. Do you test combustion appliances for safe venting?
5. Will I get a written report that ranks upgrades by cost and savings?
6. Do you also sell or install the upgrades? If so, how do you keep recommendations unbiased?
7. Do you offer a “test out” after the work is done?

Can you get a free or subsidized energy audit?

Yes, often. Many electric and gas utilities offer free or reduced-cost audits. Income-eligible households can get an audit plus free weatherization through DOE’s Weatherization Assistance Program. Some state Home Energy Rebates programs also include an assessment as part of the process.

Utility programs. Search your utility’s website for “home energy assessment” or “home energy audit,” or call customer service. Some programs give free LED bulbs, low-flow showerheads or pipe insulation during the visit.

Weatherization Assistance Program (WAP). DOE’s WAP gives free weatherization to income-eligible households, generally up to 200% of federal poverty guidelines, and households receiving SSI or TANF are often automatically eligible. States set the details. Congress funded the base program at about $329 million for fiscal year 2026. Apply through your state weatherization office or local community action agency. Our guide to help paying energy bills explains how to apply.

State Home Energy Rebates. The federal Home Energy Rebates are run by states, and only some states have launched programs. The whole-home HOMES program rewards projects that cut modeled energy use by at least 20%, or measured use by at least 15%, which usually means an assessment first. Since DOE Program Notice 26-2 took effect on May 29, 2026, households must generally address insulation and air sealing before getting appliance rebates. See home energy rebates by state to check your state.

What about the Home Energy Score?

The Home Energy Score is a DOE rating that DOE’s Energy Saver guide compares to a miles-per-gallon rating for a car. It estimates a home’s energy performance, lets owners, buyers and renters compare homes, and comes with recommendations for cost-effective upgrades. Some programs and real estate listings use it. Ask your auditor or utility whether they offer it.

How do you do a DIY home energy audit?

A DIY audit is a careful walk-through looking for air leaks, thin insulation, old equipment and wasteful habits. DOE says it will not be as thorough as a professional assessment, but it can help you find easy fixes and decide whether a pro is worth it. It costs nothing but an afternoon.

DIY checklist

1. Gather 12 months of bills. Note which months spike. Big winter bills point to heating losses. Big summer bills point to cooling and sun gain.
2. Check for drafts. DOE suggests looking where different materials meet, such as between the foundation and walls, and between the chimney and siding.
3. Inspect common leak points. Check around outlets, switch plates, window and door frames, baseboards, attic hatches, window air conditioners, and pipes, wires and vents that pass through walls.
4. Check caulk and weatherstripping. Look for cracked caulk and flattened or missing weatherstrip on doors and windows.
5. Look in the attic. If you can see the tops of the floor joists, you probably need more insulation. Our attic insulation guide shows recommended levels by region.
6. Check your ducts. Look for disconnected sections, gaps and tangled or kinked flexible ducts in attics, crawlspaces and garages.
7. Check equipment age. Note the age of your furnace, air conditioner, heat pump and water heater from their labels.
8. Change the HVAC filter. ENERGY STAR suggests checking it monthly and replacing it at least every three months.
9. Count your old bulbs. List any incandescent or halogen bulbs still in use.

A simple leak test you can do yourself

DOE describes a basic depressurization test, ideally on a cool, windy day:

1. Close all exterior doors, windows and fireplace flues.
2. Turn off combustion appliances such as a gas furnace and water heater (DOE notes you can skip this step if you prefer not to turn off the furnace).
3. Turn on all exhaust fans that blow air outside, such as bathroom fans and the range hood.
4. Pass a lit incense stick slowly around the edges of likely leak spots. If the smoke is pulled into or blown out of the room, you have found a leak.

When you are done, turn the appliances back on and confirm pilot lights relit. If you smell gas at any point, leave the house and call your gas utility from outside.

What happens after the audit?

You get a report that ranks the recommended upgrades. Often the best value comes first from air sealing and attic insulation, then duct sealing, then equipment upgrades when old systems need replacing. Use the report to collect quotes and to apply for any utility or state rebates.

DOE says sealing uncontrolled air leaks can save 10% to 20% on heating and cooling bills, and ENERGY STAR estimates sealing and insulating can save up to 10% on total annual energy bills. Our air sealing guide walks through the common fixes. If the report recommends new heating and cooling equipment, get at least three written quotes that include a proper load calculation.

Ask for a “test out” after major work. A second blower door test confirms the leakage actually went down, and a repeat combustion safety test confirms appliances still vent safely.

Bottom line

A home energy audit is the smartest first step before spending on insulation, windows or a new heating system. A professional audit with a blower door, infrared scan and combustion safety testing costs roughly $250 to $600 or more, according to DOE, but your utility may offer one free or at a discount. Choose a BPI or RESNET certified auditor, get a written report that ranks upgrades, and start with the low-cost fixes it identifies. If money is tight, check the Weatherization Assistance Program first.