Expect the cost of a home energy audit to vary substantially because these services are not interchangeable. A blower door test measures how much outside air enters through leaks in the building enclosure. A thermal camera helps locate temperature anomalies that may indicate missing insulation, air bypasses, moisture, or HVAC problems. A duct leakage test evaluates the distribution system separately, while a HERS Index report involves energy modeling by a qualified HERS rater. Request an itemized quote that identifies which tests are included, whether the home will be tested under controlled conditions, what report you will receive, and whether any HERS rating or certification is part of the service.
What a home energy audit may include
Home energy audits are often sold as packages, but the individual tests answer different questions. Before comparing prices, confirm whether the proposal includes a visual inspection, blower door testing, infrared imaging, duct leakage testing, combustion safety checks, utility-bill review, written recommendations, or HERS modeling.
A basic assessment may identify obvious insulation and air-sealing opportunities without measuring every system. A more detailed diagnostic audit uses equipment to measure air leakage and may include pressure testing of the duct system. A HERS report adds a modeling component that estimates energy performance from building characteristics, equipment, windows, air leakage, and other inputs.
Because local labor markets, home size, accessibility, travel distance, and reporting expectations vary, a legitimate auditor may not publish one universal price. The most useful comparison is between itemized scopes rather than between headline package prices.
What the blower door test measures
A blower door is a calibrated fan temporarily installed in an exterior doorway. The fan changes the pressure inside the house, commonly creating a controlled depressurization condition. The auditor measures the resulting airflow and uses the pressure difference to evaluate how leaky the building enclosure is.
During the test, the auditor may locate leaks around attic hatches, recessed lights, plumbing penetrations, electrical boxes, window and door trim, baseboards, rim joists, fireplaces, and other transitions. Smoke pencils, theatrical smoke, or other visual methods may help show airflow, although the specific tools used vary by auditor.
The test does not automatically identify every leak or prove that a particular repair will produce a certain energy savings. Results depend on test conditions, the home's configuration, combustion appliances, wind, and how the auditor interprets the findings. Ask whether the report will include the measured pressure, airflow result, test conditions, major leakage locations, and prioritized repairs.
What thermal imaging can and cannot show
A FLIR or similar infrared camera detects surface temperature differences. It can reveal patterns that suggest missing or uneven insulation, air movement through concealed cavities, thermal bridges, overheated electrical components, duct temperature differences, or possible moisture-related anomalies.
Thermal imaging is not a direct measurement of insulation thickness or air leakage. A temperature pattern can have several explanations, including sunlight, wind, framing, plumbing, HVAC operation, moisture, or differences in interior and exterior temperature. The strongest audits use the camera alongside blower door results and visual inspection rather than treating an image alone as proof of a defect.
Useful conditions for imaging depend on the season and the temperature difference across the building enclosure. Ask the auditor whether the planned conditions are suitable and whether the report will include annotated images, the suspected cause, the location, and the recommended verification or repair.
How duct leakage pressure testing differs
Duct leakage testing usually uses a duct test fan, often called a duct blaster, connected to the forced-air distribution system. The test pressurizes the ducts and measures airflow needed to maintain a specified pressure. This helps estimate leakage from supply and return ducts, air handlers, boots, plenums, and connections.
A blower door test measures leakage through the home's enclosure. A duct test measures leakage from the air-distribution system. One does not substitute for the other. Duct leakage can waste heating or cooling capacity, especially when ducts run through attics, crawl spaces, garages, or other unconditioned areas, but the correct repair depends on where the leakage occurs and whether the ducts are inside or outside the conditioned space.
Ask whether the duct test covers the entire system or only accessible portions. The auditor should explain what equipment was connected, whether registers were sealed, what pressure condition was used, and whether the report separates leakage to the outside from total duct leakage. Exact test procedures and reporting conventions can depend on the program, contract, equipment, and applicable standard.
What a HERS Index report adds
The HERS Index is an energy-rating system based on modeled home performance. A certified HERS rater collects information about the home's envelope, mechanical equipment, appliances, lighting, windows, and other features, then uses approved rating software and required verification procedures for the applicable program.
A HERS report is not simply a thermal camera report or a blower door printout. It may incorporate measured air leakage and duct performance, but it also depends on accurate inputs and modeling assumptions. A rating prepared for a new home, a renovation, a program incentive, or a code-related purpose may have different documentation and verification requirements.
Ask the rater what the report is intended to support. If you need a rating for a utility program, financing product, builder program, certification, or local requirement, confirm eligibility with the program administrator or local authority before scheduling. Requirements can vary by program and jurisdiction, and a general home energy audit may not satisfy a formal rating requirement.
What drives the quoted cost
| Cost factor | Why it matters | Questions to ask |
|---|---|---|
| Home size and layout | Larger or more complex homes take more time to inspect, test, and document. | Is the quote based on conditioned floor area, number of systems, or estimated labor? |
| Number of tests | Blower door, thermal imaging, duct testing, and HERS modeling require different equipment and work. | Which tests are included, and which are optional? |
| Access and system configuration | Attics, crawl spaces, multiple HVAC systems, additions, and inaccessible ducts can increase setup and inspection time. | Are all zones, attics, crawl spaces, and duct branches covered? |
| Report detail | A short findings sheet takes less preparation than an annotated report with priorities, photos, and repair estimates. | Will I receive raw measurements, images, priorities, and repair recommendations? |
| Travel and scheduling | Distance, occupied-home coordination, and seasonal testing conditions can affect the quote. | Are travel, return visits, or retests charged separately? |
| Formal rating or program work | HERS and incentive-related work may require credentials, software, documentation, and verification beyond a general audit. | Does the provider meet the program's current qualification requirements? |
How to compare energy audit quotes
- Describe the house accurately. Provide approximate conditioned area, construction age, additions, fuel types, HVAC systems, attic and crawl-space access, and any comfort or moisture concerns.
- Define the decision you need to make. An air-sealing plan, insulation investigation, duct repair plan, HERS rating, and incentive application may require different scopes.
- Request each test by name. Make sure the proposal separately identifies blower door testing, infrared imaging, duct leakage testing, and HERS modeling or reporting.
- Confirm test conditions and safety procedures. Ask how the auditor will handle fireplaces, combustion appliances, exhaust fans, pets, occupants, and weather conditions. Safety procedures should follow the equipment instructions and the provider's applicable professional practices.
- Review the deliverables. Look for measured results, test conditions, photographs or thermal images where relevant, locations of suspected defects, repair priorities, and limitations.
- Ask about retesting. If you plan air sealing, insulation, or duct repairs, ask whether a post-repair test is available and whether it is priced separately.
When the testing is most useful
Diagnostic testing is especially useful when rooms are persistently uncomfortable, heating or cooling costs seem inconsistent with the home's size, insulation performance is uncertain, ducts run through unconditioned spaces, or previous repairs produced disappointing results. It can also help establish a baseline before air sealing or insulation work.
Testing is less useful when the scope is vague and no one will act on the results. Before hiring an auditor, identify whether you need a repair roadmap, documentation for a program, verification of completed work, or a formal rating. The answer determines which measurements and reports are worth paying for.
Do not assume that the audit itself authorizes repairs or verifies compliance with building, electrical, plumbing, mechanical, or energy-code requirements. If the work involves a permit, incentive, sale, insurance question, or formal certification, verify the applicable requirements with the local authority, program administrator, insurer, or other responsible organization.
Questions to ask before scheduling
- Which credentials or program qualifications apply to this service?
- Will the blower door test be performed under a documented controlled pressure condition?
- Will thermal images be interpreted with other measurements rather than supplied without context?
- Does the duct test measure total leakage, leakage to outside, or another defined scope?
- Will the report list limitations, inaccessible areas, and recommended verification?
- Is a HERS Index report included, or is the service only a general energy audit?
- Are return visits, repair verification, travel, and additional HVAC systems included?
- What should occupants do with fireplaces, fuel-burning appliances, pets, and exhaust fans during testing?
Frequently asked questions
Is thermal imaging the same as a blower door test?
No. Thermal imaging shows surface temperature patterns, while a blower door measures airflow associated with pressure changes in the building enclosure. Using both can help connect a visible temperature anomaly with a likely air-sealing or insulation issue, but neither test alone identifies every defect.
Do I need duct leakage testing if I already had a blower door test?
Not necessarily, but the tests evaluate different parts of the home. A blower door evaluates the enclosure. A duct leakage test evaluates the forced-air distribution system. If ducts are in an attic, crawl space, garage, or other unconditioned area, separate duct testing may be useful.
Does every energy audit include a HERS Index report?
No. A general energy audit and a HERS rating are different services. A HERS report involves rating procedures, qualified personnel, software, documentation, and possibly program-specific verification. Confirm the required deliverable before hiring.
Can an energy audit guarantee a specific amount of savings?
No. Testing can improve the diagnosis of air leakage, insulation, and duct problems, but actual savings depend on the repairs, weather, occupancy, thermostat settings, equipment operation, utility rates, and other conditions.
Should I get the audit before or after insulation work?
Usually, testing before work establishes a baseline and helps target repairs. A follow-up blower door, duct test, or visual inspection can verify the result when the scope and the auditor make that practical. Ask whether post-repair verification is included or separately priced.