Home Energy Audit: What It Finds, What It Costs and How to Do Your Own
A home energy audit shows you exactly where your home wastes energy and what to fix first. Instead of guessing whether new windows, more insulation or a new furnace will help most, an energy audit measures your home and ranks the options. Many utilities even offer them free or at a discount. This guide explains what a professional audit includes, how the key tests work, how to do your own walk-through and how to turn findings into upgrades that pay back.
Last reviewed and updated: October 2, 2026. Written by Jeremy Jarvis.
Key takeaways
- A home energy audit finds where your home wastes energy, usually through air leaks, missing insulation and inefficient equipment.
- Professional audits often include a blower-door test, an infrared scan and a combustion safety check.
- A do-it-yourself walk-through can find many obvious problems for free.
- Heating and cooling are the largest energy uses in most homes, so air sealing and insulation often pay back first.
Efficiency also shrinks the backup power you need. Every watt you stop wasting is one your generator or battery does not have to supply.
What a home energy audit is
An energy audit, sometimes called a home energy assessment, is a structured inspection of how your home uses and loses energy. It looks at the building shell, such as walls, attic, windows and doors, and at mechanical systems, such as heating, cooling, ducts and water heating. Then it produces recommendations, usually ranked by cost and savings.
There are two broad kinds. A professional audit uses specialized tools and training. A do-it-yourself audit relies on careful observation. Both are useful, and many homeowners start with a DIY walk-through, then book a professional.
Why a home energy audit matters
Most homes leak energy in places you cannot easily see. Warm air escapes through attic gaps, around recessed lights and through duct joints. Cold air leaks in around outlets, baseboards and plumbing holes. Insulation may be thin, settled or missing in sections. These problems add up, but they are hard to find without testing.
Heating and cooling are usually the biggest targets. According to the U.S. Energy Information Administration, more than half, 52 percent in 2020, of a household’s annual energy consumption went to space heating and air conditioning. Therefore, improvements that reduce heat loss and gain often bring the largest savings.
What a professional energy audit includes
A typical professional audit follows a series of steps. First, the auditor reviews your energy bills and asks about comfort problems, such as cold rooms or high summer bills. Next, they inspect the home inside and out, including the attic, basement or crawlspace, windows, doors and mechanical equipment. Then they run diagnostic tests. Finally, they deliver a report.
Ask what your auditor’s process includes before booking, because scope varies. A basic assessment may be a visual walk-through. A comprehensive audit adds testing and detailed modeling.
The blower-door test in a home energy audit
The blower-door test measures how leaky your home is. To run it, the auditor seals a powerful fan into an exterior door frame and depressurizes the house. As outside air rushes in through every gap, a gauge measures the leakage rate. Meanwhile, the auditor walks through the house to find leaks, often with a smoke pencil or an infrared camera.
The result gives a baseline. After air sealing work, a second test shows how much improvement you achieved. Many programs require a test before and after to qualify for rebates.
Infrared scanning
An infrared camera shows temperature differences on surfaces. During an audit, especially with the blower door running, cold spots reveal missing insulation, air leaks and thermal bridges. Infrared works best when there is a meaningful temperature difference between inside and outside, so audits in mild weather may rely more on other methods.
Combustion safety testing
If your home has gas, oil or propane appliances, a good audit includes combustion safety testing. The auditor checks that furnaces, boilers and water heaters vent properly and do not produce dangerous carbon monoxide. This step matters because air sealing can change how a home breathes. A tighter home must still vent combustion gases safely. Install carbon monoxide alarms regardless.
The audit report
The report turns findings into action. A good report lists recommended improvements, estimated costs, estimated savings and priorities. It may include photos and infrared images. Some reports model how much each upgrade would reduce your bills. Use the report to plan, and ask the auditor to explain anything unclear.
A do-it-yourself home energy audit
You can find many problems yourself. Start on a windy day. Hold a lit incense stick near doors, windows, outlets and plumbing penetrations, and watch for smoke that wavers. Check weatherstripping on doors and windows. Look for gaps where pipes and wires enter walls.
Next, check the attic. Measure insulation depth and look for gaps around chimneys, recessed lights and the attic hatch. Then look at ducts in unconditioned spaces for disconnected sections or gaps. Finally, review appliances and lighting. Old refrigerators, incandescent bulbs and aging water heaters are common energy users. Our Electricity Cost Calculator shows what each appliance costs to run.
Prioritizing the results
Not every upgrade is equal. In general, start with low-cost, high-impact steps such as air sealing, weatherstripping and attic insulation. Then address ductwork, especially ducts in attics or crawlspaces. After that, consider equipment replacements when existing units reach the end of their life. Windows are often expensive relative to savings, so they usually come later unless they are badly damaged.
| Upgrade | Typical cost level | Why it often ranks high or low |
|---|---|---|
| Air sealing and weatherstripping | Low | Targets leaks that drive heating and cooling losses |
| Attic insulation | Low to moderate | Large area, often under-insulated |
| Duct sealing | Low to moderate | Leaky ducts waste conditioned air |
| LED lighting | Low | Quick savings with little effort |
| Heat pump water heater | Moderate to high | Big savings when replacing an electric tank |
| HVAC replacement | High | Best timed when equipment is near end of life |
| Window replacement | High | Often slow payback unless windows are failing |
Common home energy audit findings
Certain problems show up again and again. Attic hatches often have no insulation or weatherstripping. Recessed lights in the top-floor ceiling often leak air into the attic. Ducts in attics are frequently disconnected or poorly sealed. Basements and crawlspaces often have uninsulated rim joists. Meanwhile, older homes may have little wall insulation at all.
Many of these fixes are inexpensive. That is why audits often pay for themselves quickly through the first round of improvements.
Costs and utility programs
Professional audit costs vary by region, home size and scope. However, many utilities offer free or discounted assessments, sometimes with free LED bulbs, smart power strips or basic air sealing included. Some programs also offer rebates for recommended upgrades. Check your utility’s website and the DSIRE database before you book.
Choosing an auditor
A good auditor makes the process worthwhile. Look for training or certification from a recognized building science organization, or approval from your utility’s efficiency program. Ask what tests are included, how long the visit takes and what the report looks like. In addition, ask whether the auditor also sells upgrades. Independent auditors may give more neutral advice, while contractor-auditors can be convenient if you plan to hire them anyway.
Before the visit, prepare. Gather bills, list comfort problems and make the attic, basement and mechanical equipment accessible. During the visit, follow along and ask questions. You will learn a lot about your home in a few hours.
A room-by-room energy audit walk-through
A room-by-room approach keeps a DIY audit organized. In the kitchen, check the refrigerator’s age and door seals by closing the door on a piece of paper; if it slides out easily, the seal may be worn. Look under the sink for gaps where pipes pass through the wall. Bathroom exhaust fans should vent outdoors, not into the attic, so check where they lead.
Living areas often hide drafts around windows, doors, outlets on exterior walls and fireplace dampers. Bedrooms that are always too hot or cold can point to duct problems. Downstairs, check rim joists and plumbing penetrations in the basement. Finally, in the attic, look for gaps around the hatch, chimney and recessed lights, and check insulation depth. Write everything down, with photos.
How an energy audit helps backup power planning
An audit does more than lower bills. It also makes outages easier. A tighter, better-insulated home holds heat longer in winter outages and stays cooler longer in summer outages. That buys time and comfort when the power is out.
Efficiency also shrinks the backup system you need. If an audit leads you to replace an old refrigerator or switch to LED lighting, your essential load drops. As a result, a smaller power station or generator can carry you through. Our Home Power Plan Builder helps you plan both efficiency and backup together.
After the audit: track your results
Once you make improvements, measure the results. Compare your bills with the same months in previous years, adjusting for weather. A home energy monitor makes this easier by showing real-time and historical use. Our home energy monitor guide explains the options. Seeing results helps you decide what to tackle next.
How often to repeat an energy audit
Homes change over time. Insulation settles, caulk cracks, weatherstripping wears and new penetrations appear when cables or pipes are added. Therefore, a quick DIY walk-through every year or two is worthwhile. A professional home energy audit makes sense again after major renovations, before replacing heating or cooling equipment, or if bills rise without an obvious reason.
Selling or buying a home is another good moment. An energy audit can help buyers understand upgrade needs and help sellers highlight efficiency improvements. Some regions even encourage or require energy ratings at sale, so check local rules.
Renters and energy audits
Renters can benefit from an energy audit too, even without permission for major upgrades. A DIY walk-through can reveal drafts that removable weatherstripping or window film can fix. Swapping bulbs for LEDs, using smart power strips and adjusting thermostat schedules are renter-friendly steps. In addition, sharing findings with a landlord can encourage improvements that benefit both of you, such as attic insulation or a more efficient water heater.
Some utilities offer free assessments to renters as well, with the owner’s consent for any physical work. Ask your utility what programs are available, and check whether your state requires landlords to meet certain efficiency standards.
Home energy audit checklist
- Gather twelve months of energy bills.
- Check your utility for free or discounted audits.
- Do a DIY walk-through for drafts, insulation and duct gaps.
- Book a professional audit with blower-door testing if possible.
- Make sure combustion safety testing is included for fuel-burning appliances.
- Prioritize air sealing, attic insulation and duct sealing.
- Plan equipment replacements for end of life.
- Track bills or use a monitor to measure results.
Tools for your own audit
A few inexpensive tools help with a DIY audit, such as an infrared thermometer, a plug-in electricity meter and weatherstripping. Then explore our Energy Savings hub for upgrade guides.
Frequently asked questions about home energy audits
What does a home energy audit include?
A professional audit usually reviews your energy bills, inspects insulation, windows, ducts and equipment, runs a blower-door test to measure air leakage, uses an infrared camera to find gaps, checks combustion appliances for safety, and delivers a report with prioritized recommendations.
Is a home energy audit worth it?
Often yes, especially if your utility offers one free or at a discount. An audit finds problems that are hard to see, such as hidden air leaks and missing insulation, and helps you spend upgrade money where it saves the most.
How do I do my own energy audit?
Walk through your home looking for drafts at doors, windows and outlets, check attic insulation depth, inspect ducts for gaps, review appliance age and labels, and compare a year of energy bills. Fix the easy items first, such as weatherstripping and caulking.
Why are heating and cooling the focus of most audits?
According to the EIA, space heating and air conditioning accounted for more than half of a typical household’s annual energy consumption in 2020, so reducing heat loss and gain often brings the biggest savings.
Does my utility offer free energy audits?
Many utilities offer free or discounted home energy assessments, sometimes with free air sealing, LED bulbs or rebates for recommended upgrades. Check your utility’s website or the DSIRE database for programs in your area.
Sources and how we researched this guide
This guide is research-based. We did not perform audits for this article; we summarize how home energy assessments are commonly conducted, use EIA data on home energy use, and point to ENERGY STAR and Department of Energy resources. Your auditor’s report is the authority for your home. Found something out of date? Tell us and we will check it against the source.
- U.S. Department of Energy: Energy Saver
- EIA: Use of energy in homes
- ENERGY STAR: Products
- DSIRE: Database of state incentives
Keep planning
- Home Energy Monitor: How It Works, What It Shows and How to Choose
- How Many Watts Does a Refrigerator Use? Running, Starting and Daily kWh
- Energy Efficient Appliances: Which Upgrades Save the Most and When to Buy
- Heat Pump Water Heater: How It Works, Where It Fits and What It Saves
Go deeper: Energy Savings hub · Electricity Cost Calculator · Solar Payback Calculator
