Energy Audit: How to Assess Your Home

What Is a Home Energy Audit?

A home energy audit is a comprehensive assessment of your home's energy performance. It evaluates insulation levels, air leakage, heating and cooling system efficiency, lighting, and appliance consumption. The result is a detailed report identifying energy waste and recommending specific improvements with estimated costs and savings.

The Department of Energy estimates that implementing audit recommendations can save the average household $200-$600 per year — a 20-30% reduction in total energy costs. With payback periods typically ranging from 1-5 years for most recommended improvements, an energy audit is one of the smartest investments you can make in your home.

Professional Energy Audit vs DIY Audit

What a Professional Energy Audit Includes

A professional energy audit, conducted by a certified energy auditor, typically includes the following assessments:

1. Blower Door Test

A blower door is a powerful fan mounted in an exterior door frame that depressurizes your home. By measuring the airflow needed to maintain a specific pressure difference, the auditor calculates your home's air infiltration rate. This test identifies the total amount of air leakage and helps pinpoint specific leak locations.

A typical older home measures 2,000-4,000 CFM50 (cubic feet per minute at 50 pascals of depressurization), while a well-sealed new home should measure under 1,500 CFM50. Each 100 CFM50 reduction in leakage saves approximately $50-$100 per year in energy costs.

2. Thermal Imaging (Infrared Camera)

An infrared camera reveals temperature differences on walls, ceilings, and floors, highlighting areas with missing insulation, air leaks, and thermal bridges. This non-invasive technique can identify problems that would otherwise require cutting holes in walls to discover.

Common findings include uninsulated wall cavities, compressed insulation, gaps around electrical outlets, and missing insulation around recessed lights. Thermal imaging is most effective when there is at least a 20°F temperature difference between inside and outside, so audits are best performed in winter or summer.

3. Duct Leakage Test

If you have forced-air heating or cooling, a duct blaster test pressurizes the duct system to measure total leakage. The average home loses 20-30% of conditioned air through duct leaks. The test identifies whether duct sealing is needed and quantifies the potential savings.

4. Combustion Safety Testing

For homes with gas, oil, or wood heating appliances, the auditor tests for combustion safety including carbon monoxide levels, draft pressure, and spillage. This ensures that your heating equipment is operating safely and efficiently.

5. Insulation Assessment

The auditor measures insulation depth and quality in the attic, checks wall insulation through infrared imaging or by removing outlet covers, and assesses basement/crawlspace insulation. They compare your current insulation levels to recommended R-values for your climate zone.

6. Appliance and Lighting Inventory

The auditor catalogs all major appliances, noting their age, efficiency rating, and estimated energy consumption. They identify opportunities to upgrade to more efficient models and estimate the payback period for each recommendation.

How to Conduct a DIY Energy Audit

If a professional audit is not in your budget, you can perform a meaningful self-assessment. Here is a step-by-step DIY energy audit:

Step 1: Analyze Your Utility Bills

Gather 12 months of electricity and gas bills. Calculate your average monthly usage and identify seasonal patterns. Compare your usage to similar homes in your area:

If your usage is 20%+ above the average for your home size, you likely have significant efficiency opportunities.

Step 2: Inspect the Attic

Check your attic insulation depth and condition. Use a ruler to measure insulation depth:

Also check for: gaps in insulation around recessed lights, chimneys, and attic hatches; compressed or wet insulation; and air leaks around plumbing and electrical penetrations.

Step 3: Check for Air Leaks

On a windy day, use an incense stick or smoke pencil to detect air movement around:

• Window and door frames
• Electrical outlets and switch plates (especially on exterior walls)
• Baseboards and crown molding
• Plumbing penetrations under sinks
• Attic hatch or stairs
• Recessed light fixtures
• Dryer vent and bathroom exhaust penetrations
• Mail slot and pet doors

Step 4: Inspect HVAC Equipment

Check your heating and cooling equipment for efficiency and maintenance needs:

• Locate the manufacture date on your furnace/AC — equipment over 12-15 years old is a candidate for replacement
• Check and replace air filters (should be done monthly during heating/cooling season)
• Inspect visible ductwork for disconnections, gaps, and crushed sections
• Check that supply and return vents are unobstructed
• Listen for unusual noises from the furnace or AC compressor
• Look for rust, soot, or corrosion on heating equipment

Step 5: Examine Windows and Doors

Check for:

• Single-pane windows (consider storm windows or replacement)
• Failed window seals (condensation between panes indicates seal failure)
• Missing or damaged weatherstripping
• Gaps around window and door frames (check with a dollar bill — if it slides easily between the weatherstripping and frame, the seal is inadequate)
• Cracked or missing caulk around exterior frames

Step 6: Assess Water Heating

• Check the age of your water heater (tank heaters last 10-12 years)
• Measure hot water temperature (should be 120°F; higher wastes energy)
• Check for leaks at connections and the temperature/pressure relief valve
• Feel the tank — if it is warm to the touch, it needs an insulating blanket
• Check for sediment buildup (drain a quart — if water is discolored, flush the tank)

Step 7: Inventory Lighting and Appliances

• Count remaining incandescent bulbs and calculate savings from LED replacement
• Check appliance age and efficiency ratings
• Look for Energy Star labels on major appliances
• Check for phantom loads by turning off all lights at night and observing the electric meter

Professional Energy Audit Costs

Many utilities offer free or discounted energy audits as part of their energy efficiency programs. Check with your utility before paying for a private audit. Some states also offer free audits through weatherization programs for income-eligible households.

Understanding the Audit Report

A professional audit report should include:

1. Current energy use breakdown: How much energy your home uses and where it goes
2. Air leakage rate: Measured in CFM50, with comparison to optimal levels
3. Insulation assessment: Current R-values vs recommended values for each area
4. Duct leakage: Percentage of conditioned air lost through ducts
5. Prioritized recommendations: Ranked by cost-effectiveness (savings per dollar invested)
6. Estimated costs and savings: For each recommended improvement
7. Available rebates and incentives: Programs that can offset improvement costs
8. Safety findings: Any combustion safety or indoor air quality concerns

Prioritizing Improvements: What to Fix First

Not all audit recommendations are equally cost-effective. Prioritize improvements using the Simple Payback method: divide the cost by the annual savings. Projects with payback periods under 5 years should be done first.

Acting on Audit Results

After receiving your audit report, create an action plan:

1. Tackle quick wins first: LED bulbs, thermostat settings, and air filter replacements require minimal investment and provide immediate savings.
2. Address air sealing: This is typically the most cost-effective improvement and should be done before adding insulation.
3. Upgrade insulation: Once air leaks are sealed, add insulation starting with the attic (highest ROI) and working down to walls and floors.
4. Seal ductwork: If your audit found significant duct leakage, prioritize sealing to prevent wasted conditioned air.
5. Plan equipment upgrades: If your furnace or AC is nearing end of life, research high-efficiency replacements and take advantage of off-season installation discounts and rebates.
6. Re-audit after improvements: Some auditors offer a discounted follow-up test to verify that improvements achieved the expected results.

Finding a Qualified Energy Auditor

Look for auditors with the following certifications:

• BPI (Building Performance Institute) Certified: The gold standard for residential energy audits
• RESNET (Residential Energy Services Network) HERS Rater: Specializes in home energy rating systems
• Licensed contractor: Ensure the auditor carries proper licensing and insurance
• Utility-recommended: Many utilities maintain lists of approved auditors

Avoid auditors who are also contractors trying to sell you specific products — their recommendations may be biased toward their services. An independent auditor has no financial incentive to recommend specific improvements and will provide objective, cost-effective recommendations.

Tax Credits and Rebates for Energy Audits and Improvements

• Federal 25C tax credit: Covers 30% of audit costs up to $150, plus 30% of improvement costs up to $1,200 annually
• Utility rebates: Many utilities offer rebates for audits and recommended improvements
• State programs: Check DSIRE for state-specific incentives for energy efficiency improvements
• Weatherization Assistance Program: Free audits and improvements for income-eligible households