Quick answer
A home energy audit is an inspection of a house, backed by diagnostic tests, that finds where and how the home uses and loses energy and ranks the improvements that would cut that waste.
ENERGY STAR also calls it a home energy assessment. A professional audit usually includes a blower door test, an infrared scan and safety checks on fuel-burning equipment, and ends with a written report.
Quick facts
The key facts about Home Energy Audit, with sources:
- Also called
- Energy assessment, home performance assessment 1
- Core tests
- Blower door, infrared camera, combustion safety 2
- Typical length
- A few hours; often 3 to 4 for a home 2
- Federal tax credit
- The 25C audit credit expired for work after 31 Dec 2025 7
- Typical savings from sealing and insulating
- About 11% of total energy cost, national average estimate 5
Key takeaways
- An energy audit is a measured inspection, not a sales visit: it should include tests and a written report.
- The heart of a professional audit is a blower door test, an infrared scan and combustion safety checks.
- A good report ranks fixes by impact, so you spend first where the house leaks most.
- ENERGY STAR estimates sealing and insulating saves about 11% of total energy cost on average, more in cold climates.
- The federal audit tax credit (25C) expired at the end of 2025; look to utilities and state programs instead.
What an energy audit actually is
An energy audit answers three questions about a house: where does the energy go, where is it wasted, and what should be fixed first. ENERGY STAR defines it as an assessment that determines where, when, why and how energy is used in a home, built from inspections, diagnostics, data collection, analysis and reporting 1.
The Vermont Department of Public Service puts the goals in plain terms. An audit should pinpoint where a building uses and loses energy, check whether heating and cooling run safely and efficiently, explain how to cut drafts, and identify improvements that may save money 2.
Two things set a real audit apart from a walk-through. First, it uses test equipment, so findings are measured rather than guessed. Second, it ends with a report that you can hand to any contractor. That makes it a planning tool, much like a scope of work is for a remodel.
What happens during a professional audit
Order and tools vary by auditor, but most full audits follow a similar path. The steps below draw on the Vermont audit guide and the ENERGY STAR glossary of home performance terms 21.
- Interview and bills. The auditor asks about comfort problems, drafts and past work, and may review a year of energy bills.
- Exterior and interior walk-through. The auditor checks the shell: attic, walls, windows, doors, basement or crawl space.
- Combustion safety testing. Furnaces, boilers, water heaters and stoves are checked for fuel leaks, carbon monoxide and proper venting 1.
- Blower door test. A calibrated fan depressurizes the house to measure total air leakage. See our blower door test page for how the score works.
- Infrared scan. While the house is under pressure, a thermal camera shows cold or hot spots where insulation is missing or air leaks in 2.
- Moisture and air quality notes. The auditor may suggest ventilation or moisture fixes as part of the plan 2.
- Report and walk-through of results. You get a written list of findings, ranked by priority.
- Air leakageBlower door test
- InsulationInfrared scan and attic check
- Heating and coolingEfficiency and safety
- Combustion safetyFuel leaks, CO and venting
- Ventilation and moistureIndoor air quality
- Energy billsWhere the money goes
A professional audit ties each finding back to a measured test or an inspection. Source: [2] [1]
Types of energy audits and ratings
| Type | What it involves | Best for |
|---|---|---|
| Do-it-yourself check | You look for drafts, check attic insulation depth and review bills | A first look before hiring anyone |
| Utility or walk-through audit | A short visit, often without full diagnostic testing | Finding programs and quick fixes |
| Comprehensive professional audit | Blower door, infrared scan, combustion safety and a report 2 | Planning a major remodel or energy upgrade |
| Home performance assessment | An evaluation by a Home Performance with ENERGY STAR expert 1 | Homes in areas with a local program sponsor |
| HERS rating | A RESNET-certified rater inspects and calculates a HERS Index score 9 | New homes, code compliance paths and resale data |
An audit is not a home inspection
A home inspection before a sale looks for defects and safety problems. An energy audit measures energy use and loss. Some issues overlap, such as roof leaks or failing equipment, but neither replaces the other.
Example: reading ENERGY STAR’s savings estimate for your climate
ENERGY STAR modeled a typical 1970s to 1980s house of about 1,700 square feet and estimated what sealing air leaks and adding insulation would save in each climate zone 5.
The figures below are ENERGY STAR’s model results; the final column is our own reading of them for an example household. They are averages, not a promise for your home.
| Climate zone | Estimated savings, total energy bill | Estimated savings, heating and cooling only |
|---|---|---|
| Zone 7 (far north) | 15% | 19% |
| Zone 5 (northern states) | 12% | 16% |
| Zone 4 (middle band) | 12% | 17% |
| Zone 3 (warm south) | 8% | 14% |
| Zone 1 (hottest) | 5% | 7% |
| National average | 11% | 15% |
| Example household in zone 5 | If heating and cooling are 50 units of a 100-unit bill | About 16% of 50 = 8 units saved |
The pattern matters more than any single number. The same air sealing and insulation work saves roughly three times as much in the far north as in the hottest zone, because there is more heating to save. An audit tells you whether your house is typical or an outlier.
What the audit report should contain
The report is what you are paying for. At a minimum it should list each test with its result, the problems found, and a ranked list of improvements.
The IRS rules for the old audit tax credit are a useful checklist even now that the credit has expired: they asked for a written report and inspection that identified the most significant and cost-effective improvements, with an estimate of energy and cost savings for each 7.
Look for these items: the blower door result (CFM50 and ACH50), infrared photos with notes, combustion safety results for each appliance, insulation levels found by area, and the auditor’s name and certification.
Ask how savings were estimated. A model like the one ENERGY STAR used for its national figures is more reliable than a rule of thumb 5.
You can then turn the ranked list into bids. Our quote comparison tool helps you line up proposals against the same findings.
Walk the house with the auditor
Vermont’s guidance notes auditors often encourage you to walk through with them. Do it. Seeing the infrared image of a leak above your bedroom makes the report far easier to act on.
Why an audit is worth doing before a remodel
What it gives you
What it will not do
- Fix anything by itself; the work still has to be done.
- Guarantee the modeled savings on your bill.
- Replace a structural, electrical or plumbing inspection.
- Find leaks hidden behind finished walls with full certainty.
Limits of what an audit can tell you
An audit is a snapshot. Savings estimates come from energy models built on assumptions about weather, fuel prices and how you live. ENERGY STAR’s own figures come from modeling a "typical" house, then checking against field experience 5. Your house may differ.
Audits also depend on access. If the auditor cannot get into an attic, a crawl space or behind finished walls, those areas get less attention. Vermont advises clearing access to heating equipment, basement and attic before the visit 2.
Finally, the quality of the report depends on the auditor. A report written to sell one product, such as only windows, is a red flag. A useful report compares options.
What drives the cost of an audit, and who pays
We do not publish audit prices; they vary by region, house size and depth.
The cost drivers are clear: the number of tests (blower door, duct leakage, combustion safety), the size and complexity of the house, whether infrared imaging is included and whether you need a retest after the work.
Vermont notes that most contractors charge for assessments to cover their time and equipment 2.
Help with the cost has shifted. Until the end of 2025 the federal Energy Efficient Home Improvement Credit (25C) covered part of a qualifying audit. The IRS lists the credit as available only for improvements made through December 31, 2025, so it has expired 7.
The federal Home Energy Rebates programs, run through state energy offices, are available only in select states, according to DOE 8. Many utilities also offer audit rebates, as ENERGY STAR notes 6.
An audit report has no warranty or lifespan, but it ages. Plan a new audit after major changes, such as an addition or an HVAC replacement. Use our whole-home budget tool to see how audit-driven fixes fit a larger plan.
How to book and use an energy audit
You can run this process yourself. The testing is done by a trained, certified auditor.
- Check your utility and state energy office for audit programs and rebates before you book 86.
- Choose a qualified auditor: a BPI-certified building analyst or energy auditor, or a RESNET HERS rater 109.
- Ask what is included: blower door, infrared scan, combustion safety, duct testing and a written report.
- Prepare the house: clear access to the attic, basement and heating equipment, and close windows 2.
- Join the walk-through and ask questions as the auditor works.
- Turn the ranked list into a scope of work and get bids.
- Air seal before you insulate; Vermont and ENERGY STAR both stress sealing first 36.
- Retest after the work so you can see the result.
Keeping the audit useful over time
An audit keeps paying off if you treat the report as a living plan.
- Keep the report and photos with your house records; they help a future buyer or contractor.
- Tick items off as they are done, with dates and invoices.
- Stage work into other projects. Vermont suggests hard-to-reach spots may be cheaper to fix when another project opens them up 4.
- Retest after big changes, such as new windows, an addition or attic work.
- Recheck combustion safety whenever the house gets tighter or equipment is replaced.
Warning signs an audit is overdue, and red flags
- Drafty rooms, hot or cold ceilings, or uneven temperatures between rooms, which ENERGY STAR lists as common symptoms of attic insulation problems 6.
- Ice dams along the roof edge in winter 6.
- High heating or cooling bills with no clear cause.
- Condensation or mold on walls or windows; EPA says the key to mold control is moisture control 12.
- Red flag: an "audit" with no tests, no written report, or a report that recommends only the product the auditor sells.
Combustion safety comes first
Tightening a house can change how gas or oil appliances vent. Vermont notes safety tests are done before and after air sealing so exhaust gases do not spill indoors. Never skip the combustion check, and keep working carbon monoxide alarms on every level.
Call a qualified HVAC contractor or your gas utility right away if the auditor finds a gas leak, a cracked heat exchanger or carbon monoxide.
Standards, certifications and program rules
No federal audit license. There is no single federal license for energy auditors. Programs and codes instead rely on certifications. The Building Performance Institute (BPI) certifies building analysts, energy auditors and quality control inspectors 10. RESNET certifies HERS raters, who inspect and calculate a home’s energy performance 9.
Energy code testing. For new dwelling units, 2021 IECC Section R402.4.1.2 requires an air leakage test reported at 50 pascals, using ANSI/RESNET/ICC 380, ASTM E779 or ASTM E1827, with a signed report to the code official 11.
An audit of an existing home is not required by the code, but it often uses the same test methods.
Codes as a performance path. RESNET reports that state and local governments are adding HERS Index targets as a performance compliance option in their energy codes 9. Check what your jurisdiction adopted.
Tax credit status. The IRS lists the Energy Efficient Home Improvement Credit, including the home energy audit portion, as available for improvements made through December 31, 2025 7. It has expired and should not be planned on for new work.
Energy audit vs. similar services
| Service | What it is | Main difference from an audit |
|---|---|---|
| Home energy audit | Inspections, diagnostics and a report on energy use 1 | The baseline |
| Blower door test | One test of air leakage 1 | Part of an audit, not the whole audit |
| HERS rating | A scored energy rating by a certified rater 9 | Produces a standard index score; common for new homes |
| Home inspection | A pre-sale check for defects | Looks for damage, not energy losses |
| HVAC load calculation | Sizing math for heating and cooling equipment | Uses audit data but answers a different question |
Common myths about energy audits
- Myth An energy audit is just a sales pitch for new windows.
- Reality A real audit includes measured tests and ranks options by impact 2; windows are rarely the first fix.
- Myth My house is new, so it does not need one.
- Reality Newer homes can still leak through ducts, attic hatches and penetrations; the code now tests new homes for exactly this reason 11.
- Myth More insulation always fixes drafts.
- Reality Vermont notes insulation without air sealing first loses much of its value 3.
- Myth The federal tax credit will pay for part of it.
- Reality The 25C credit expired for improvements after December 31, 2025, per the IRS 7.
- Myth Savings will be the same in every climate.
- Reality ENERGY STAR’s modeled savings run from about 5% to 16% depending on climate zone 5.
How climate and your state change the payoff
Two local variables shape what an audit is worth.
The first is your IECC climate zone: ENERGY STAR’s model shows much larger savings from sealing and insulating in northern zones (about 15% to 16% of the total bill in zones 7 and 8) than in the hottest zones (5% to 6% in zones 1 and 2) 5.
The second is your state energy office, which runs the federal Home Energy Rebates where they are live; DOE says they are available only in select states 8. Utility audit programs also vary by provider.
When an energy audit should shape your remodel
Get an audit before you spend on insulation, air sealing, HVAC replacement or windows. It is also smart before a large project such as finishing a basement or adding space, since the work may open walls and ceilings where leaks are easy to fix.
If you are only replacing one appliance or making a small repair, a full audit may be more than you need.
Your next step: call your utility to ask about audit programs, then book a certified auditor and ask for a written, ranked report.
- If You plan insulation, air sealing or new HVAC
- Then Yes, audit first so bids target real losses
- If Rooms are drafty or bills are high without a clear cause
- Then Yes, testing finds what you cannot see
- If A rebate program requires before-and-after proof
- Then Yes, book a calibrated test
- If You are making one small, known repair
- Then Probably not; fix it directly
Questions about Home Energy Audit
What does a home energy audit include?
A professional audit usually includes a walk-through of the house, a blower door test to measure air leakage, an infrared camera scan, and safety tests on fuel-burning appliances. It ends with a written report that ranks improvements. Some audits also test duct leakage and review a year of energy bills.
How long does a home energy audit take?
Most home audits take a few hours. Vermont’s Department of Public Service says a thorough home assessment may take three to four hours and usually happens on a weekday. Larger or more complex homes take longer. Clear access to the attic, basement and heating equipment to keep it on schedule.
Is a home energy audit worth it?
It is usually worth it before any major energy spending, because it shows where the house loses the most.
ENERGY STAR estimates that sealing and insulating save about 11% of total energy costs on average, and up to about 16% in the coldest climate zone. An audit tells you which of those fixes fit your house.
Can I do my own energy audit?
You can do a basic check yourself. Look for drafts around doors and windows, check how deep your attic insulation is and review your bills. A do-it-yourself check cannot measure total air leakage or test combustion safety, though. For those, you need a trained auditor with calibrated equipment.
Is there still a tax credit for a home energy audit?
No, not at the federal level for new work. The IRS lists the Energy Efficient Home Improvement Credit, which included a capped credit for a qualifying audit, as available for improvements made through December 31, 2025. Check your utility and state energy office for current audit rebates.
Who is qualified to do a home energy audit?
Look for a BPI-certified building analyst or energy auditor, or a RESNET-certified HERS rater. Many utility programs keep lists of approved auditors. Ask for the certification number, a sample report and what tests are included before you book.
What is the difference between an energy audit and a HERS rating?
An energy audit diagnoses an existing home and ranks fixes. A HERS rating, done by a RESNET-certified rater, produces a standard HERS Index score that compares the home with a reference home. Ratings are common for new construction and code compliance, while audits are more common before upgrades.
What should I do after an energy audit?
Start at the top of the ranked list. In most homes that means air sealing first, then insulation, then equipment. Vermont and ENERGY STAR both advise sealing air leaks before adding insulation. Get bids that reference the audit findings, and retest after the work so you can see the result.
Does an energy audit check for safety problems?
A professional audit checks combustion safety on fuel-burning appliances, looking for fuel leaks, carbon monoxide and venting problems. It is not a full safety or structural inspection. Report any gas smell or alarm to your utility or an HVAC contractor right away, whatever the audit schedule.
Sources
- ENERGY STAR, Glossary of Common Terms (energy audit, home energy assessment, combustion safety test), retrieved .
- Vermont Department of Public Service, Vermont Energy Saver: Energy Audits, retrieved .
- Vermont Department of Public Service, Vermont Energy Saver: Air Sealing, retrieved .
- Vermont Department of Public Service, Vermont Energy Saver: Insulation, retrieved .
- ENERGY STAR, Methodology for Estimated Energy Savings (Table 1, savings by climate zone), retrieved .
- ENERGY STAR, Attic Insulation Project, retrieved .
- IRS, Energy Efficient Home Improvement Credit, retrieved .
- U.S. Department of Energy, Home Energy Rebates Programs, retrieved .
- RESNET, HERS Index and Energy Codes, retrieved .
- Building Performance Institute (BPI), certifications, retrieved .
- ICC, 2021 International Energy Conservation Code, Chapter 4 [RE] Residential Energy Efficiency (R402.4.1.2), retrieved .
- U.S. EPA, A Brief Guide to Mold, Moisture and Your Home, retrieved .
Expert review
Written by the HyreRemodel Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: The definition comes from the ENERGY STAR glossary. Audit steps, length and safety testing come from the Vermont Department of Public Service audit, air-sealing and insulation pages.
Savings figures are ENERGY STAR’s modeled estimates by climate zone, quoted as published. Tax-credit status is from the IRS credit page; rebate status from DOE.
Code testing rules are from 2021 IECC R402.4.1.2. DOE Energy Saver audit pages returned "page not found" on the retrieval date and are not used. No prices are given.
Suggest a correction. We fix errors and say what changed.