Home Energy Audit: What It Is, What It Costs, and What to Expect

If your energy bills seem high but you're not sure where to start — insulation, windows, HVAC, air sealing, or something else — a professional home energy audit gives you a prioritized action plan. It's one of the highest-return investments a homeowner can make before spending money on upgrades.

Here's everything you need to know before scheduling one. For an overview of the most impactful upgrades the audit might recommend, see our energy saving tips ranked by ROI.

What Is a Home Energy Audit?

A home energy audit is a systematic assessment of how energy flows through your home. A certified auditor uses diagnostic tools and visual inspection to identify:

• Where conditioned air is escaping (air leaks)
• Where insulation is inadequate or missing
• How efficiently your HVAC system is performing
• Whether your water heater, appliances, and lighting are energy-efficient
• Any health and safety issues (combustion safety, carbon monoxide risk)

The output is a report with specific findings and prioritized recommendations, typically including estimated cost of each upgrade and expected annual savings.

Types of Energy Audits

Utility-Sponsored Free Audit

Many electric and gas utilities offer free or subsidized energy audits as part of their demand-side management programs. These typically involve:

• A utility representative walking through your home
• Basic visual inspection
• Utility bill analysis
• A short report with recommendations

Best for: Getting a starting point at no cost. Less thorough than a professional audit.

Professional Home Energy Assessment

A certified energy auditor (BPI-certified or RESNET/HERS-rated) conducts a full diagnostic assessment using specialized equipment. This is what most homeowners mean when they say "energy audit."

Cost: $200–$600, averaging around $400 for a 2,000 sq ft home.

Some states and utilities reimburse part of this cost through rebate programs — check Database of State Incentives for Renewables & Efficiency (DSIRE) before paying full price.

New Construction / Pre-Purchase Audit

If you're buying a home, a pre-purchase energy audit evaluates the home's energy profile and identifies deferred maintenance or upgrade needs that affect your operating costs. Some buyers negotiate seller credits based on audit findings.

What Auditors Actually Test

1. Blower Door Test

The most important diagnostic tool. The auditor installs a fan in an exterior doorframe, pressurizes or depressurizes the house, and measures air leakage. Results are expressed as ACH50 (air changes per hour at 50 pascals of pressure).

A typical older home might score 10–15 ACH50. An energy-efficient home targets 3–5 ACH50. A net-zero home might target under 1 ACH50.

The blower door test makes air leaks visible — while the fan runs, you can feel drafts around outlets, plumbing penetrations, recessed lights, attic hatches, and other infiltration points.

2. Thermal Imaging (Infrared Camera)

An infrared camera reveals temperature differences in walls, ceilings, and floors — making missing insulation, air leaks, and thermal bridges visible that can't be seen by eye. This is typically done during the blower door test, when the pressure differential makes temperature differences more pronounced.

3. Duct Leakage Test

If your home has forced-air heating and cooling, the auditor tests duct leakage. The average American home loses 20–30% of conditioned air through duct leaks before it reaches living spaces. Even a 10% reduction in duct leakage meaningfully improves system efficiency.

4. Combustion Safety Analysis

If you have gas appliances (furnace, water heater, range, fireplace), the auditor tests for combustion gases and checks for carbon monoxide risk. This is a safety check that can be life-saving — combustion appliance zone testing identifies backdrafting conditions that can allow carbon monoxide to enter living spaces.

5. Visual Inspection Checklist

Beyond diagnostic testing, auditors visually assess:

• Attic insulation depth and coverage
• Basement/crawl space insulation and moisture
• Window and door condition
• HVAC system age, condition, and filter
• Water heater type, age, and insulation
• Lighting (LED vs. incandescent)
• Appliance age and Energy Star status

What the Report Includes

A good energy audit report gives you:

Priority rankings: Which upgrades offer the best payback first. Typically air sealing and insulation come before windows or HVAC replacement.

Cost estimates: Ballpark cost for each recommended improvement.

Savings projections: Estimated annual dollar savings from each upgrade.

Rebate and incentive info: Which improvements qualify for federal tax credits, utility rebates, or state programs.

Health and safety findings: Any combustion safety issues or moisture problems found.

Sample finding from a typical audit:

| Recommendation | Estimated Cost | Annual Savings | Payback | |---|---|---|---| | Air seal attic penetrations | $300–$600 | $180–$280 | 1.5–3 years | | Add R-30 attic insulation | $800–$1,800 | $200–$350 | 3–5 years | | Seal and insulate ducts | $400–$1,200 | $200–$400 | 2–4 years | | Replace water heater (heat pump) | $1,200–$2,000 | $300–$500 | 3–5 years | | Replace windows | $8,000–$15,000 | $200–$400 | 20–40 years |

This illustrates a critical finding from most audits: windows are usually the last upgrade to make financial sense, despite being what most homeowners think of first. Air sealing and insulation almost always have faster payback. That said, when windows do make sense, our best energy-efficient windows guide and the ENERGY STAR window tax credit guide explain how to maximize your savings on the replacement.

Federal Tax Credit for Energy Audits

The Inflation Reduction Act (IRA) includes a 30% tax credit for home energy audits, up to $150, under Section 25C. The audit must be conducted by a certified auditor meeting IRS requirements. This helps offset the cost of a professional assessment.

Additionally, many of the upgrades recommended in the audit qualify for their own IRA credits:

• Air sealing and insulation: 30% credit, up to $1,200
• Heat pumps: 30% credit, up to $2,000
• Heat pump water heaters: 30% credit, up to $2,000

How to Find a Certified Auditor

Look for auditors with one of these credentials:

BPI (Building Performance Institute): The gold standard for residential energy auditors. Find certified contractors at bpi.org.

RESNET HERS Rater: Primarily used for new construction ratings but also performs existing home audits.

Energy Star Partner: Contractors who work with the EPA's Home Performance with Energy Star program.

Many utility rebate programs require auditors from their approved contractor list — check with your utility before hiring.

How to Prepare for Your Audit

Gather 12 months of utility bills: The auditor uses bill analysis to establish a baseline. Many utilities let you download this data from their online portal.

List known problem areas: Drafty rooms, areas that are hard to heat or cool, recurring high bills in certain seasons.

Clear access to attic and crawl space: The auditor needs to see insulation, framing, and mechanical systems.

Be home for the full audit: A thorough audit takes 2–4 hours. Your presence lets you ask questions and understand findings in context.

Don't weatherstrip doors right before the test: This can artificially improve blower door results. The goal is an accurate baseline reading, not the best possible score.

The ROI of Getting an Audit

A $400 energy audit that identifies $600/year in potential savings pays for itself in under a year — assuming you act on the recommendations. Many homeowners who complete recommended air sealing and insulation upgrades see 15–25% reductions in annual energy bills.

More importantly, an audit gives you a prioritized action plan so you spend upgrade money where it has the most impact — not on impressive-looking improvements (like new windows) that offer poor payback. Use our home upgrade planner to build a multi-year improvement roadmap from your audit findings, and explore our solar ROI calculator if solar comes up as a recommendation.