The Home Energy Audit: What It Checks, What It Costs, and Whether It Is Worth It Before Any Improvement Project
Before you replace your HVAC, add attic insulation, or upgrade your windows, there is one step that tells you exactly where your home is losing energy and how much each improvement will actually save. Most homeowners skip it because they do not know it exists. It is called a home energy audit, and for homes built before 2000, it is almost always worth doing first.
Replacing Systems Without Knowing Where Your Energy Is Going
A homeowner who replaces their HVAC without first knowing that 40 percent of their home’s conditioned air is escaping through duct leaks may install a highly efficient new system and be disappointed that their utility bills did not drop as much as the contractor projected. Energy improvements work best when they address the actual sources of energy loss in a specific home.
Why Improvements Sometimes Disappoint
The most common reason home energy improvements underperform expectations is that the improvement was selected based on assumptions rather than data. A home with poor air sealing at the top and bottom plates of exterior walls will continue to lose conditioned air through those gaps after an attic insulation upgrade — because insulation reduces heat transfer through the flat ceiling surface but does not address air movement through gaps in the building envelope.
The U.S. Department of Energy estimates that air sealing and insulation improvements combined reduce heating and cooling costs by 15 percent on average for California and Nevada homes. When selected based on energy audit data rather than assumptions, actual savings are consistently higher.
What a Professional Home Energy Audit Actually Includes
The Blower Door Test
A blower door is a calibrated fan mounted in an exterior door frame that depressurizes the home to a standard test pressure. While the home is depressurized, the auditor measures the total air leakage rate of the building envelope. The result is air changes per hour (ACH50), which quantifies how leaky the home is relative to a tight, energy-efficient standard. The blower door test identifies that air leakage is a problem. Thermal imaging identifies where.
Thermal Imaging Inspection
An infrared camera reveals temperature differences on wall and ceiling surfaces that are invisible to the naked eye. Areas where insulation is missing, where air is infiltrating through gaps, or where moisture is present show up as distinct temperature anomalies. A skilled auditor can identify missing insulation in specific wall bays, air bypasses at top plates, and duct leakage locations in the attic — all without opening walls.
Duct Leakage Testing
In California and Nevada homes, HVAC ducts routed through unconditioned attic space are a primary source of energy loss. A duct blaster test pressurizes the duct system and measures how much conditioned air leaks out before reaching the living space. The California Energy Commission has documented that the average California home loses 20 to 30 percent of HVAC output to duct leakage.
Combustion Safety Testing
For homes with gas appliances, the audit includes combustion safety testing to verify that gas-fired equipment is operating safely and combustion byproducts are properly venting to the exterior. This is a standard component of a BPI-certified professional audit.
What the Audit Report Provides
A complete professional audit delivers: a prioritized list of improvements with projected energy savings for each, total air leakage rate and where it is occurring, duct leakage measurements and locations, thermal imaging documentation of insulation gaps, and a DOE Home Energy Score from 1 to 10 that benchmarks the home’s performance relative to similar homes.
What a Home Energy Audit Costs
Professional home energy audits in Northern California and Nevada typically run $200 to $500 for a complete assessment. PG&E and NV Energy periodically offer subsidized programs for qualifying customers. BPI-certified auditors are the professional standard to look for.
The cost of the audit is almost always recovered in better-selected improvements. A homeowner who spends $300 on an audit and learns that duct leakage is the primary energy problem — not insulation — saves the cost of an insulation project they did not need and targets the improvement that will actually move their utility bill.
Improvements Selected From Audit Data Perform Better
A homeowner who completes an energy audit before planning improvements has actual data about their specific home. They know where energy is being lost, in what quantities, and what each improvement will return in monthly savings. They prioritize correctly and do not skip the improvement that would have made the biggest difference.
An energy audit does not cost you money. It tells you where you are spending money you should not be spending, and where the improvements will pay you back the most.
FREQUENTLY ASKED QUESTIONS
How much does a home energy audit cost in California?
Professional home energy audits in Northern California typically run $200 to $500 for a complete assessment including blower door test, thermal imaging, duct leakage testing, and written report. PG&E offers a free online Home Energy Checkup tool at pge.com as a starting point. Some California utilities offer subsidized professional audits for qualifying customers.
What does a home energy auditor check?
A complete BPI-certified home energy audit checks: total building air leakage using a blower door test, location of air leaks and insulation gaps using thermal imaging, duct leakage quantity and location using a duct blaster pressurization test, combustion safety for all gas appliances, insulation levels in attic, walls, and crawl space, and window and door performance.
Is a home energy audit worth it?
For most homes built before 1990 in California and Nevada, yes. The audit is most valuable when improvements are being planned and the homeowner wants data to prioritize correctly, when utility bills are higher than expected, or when there are comfort problems that standard explanations have not resolved.
What is a blower door test?
A blower door test uses a calibrated fan mounted in an exterior door frame to depressurize the home to a standard test pressure of 50 pascals. The auditor measures total air leakage in cubic feet per minute, which converts to air changes per hour at 50 pascals (ACH50). A well-sealed modern home achieves ACH50 of 3 or lower. Many California homes from the 1960s to 1980s test at 10 to 15 ACH50.
Does PG&E offer home energy audits?
PG&E offers a free online Home Energy Checkup tool at pge.com that analyzes your usage patterns and suggests improvements. For a professional on-site audit with blower door testing and thermal imaging, PG&E periodically offers subsidized programs for qualifying customers. BPI-certified independent auditors are available throughout the Sacramento and Bay Area service areas.
What home improvements do energy audits most commonly recommend?
The most common findings from home energy audits in Northern California and Nevada homes are: air leakage at top and bottom plates of exterior walls, attic insulation below current R-value recommendations, HVAC duct leakage in unconditioned attic space, exhaust fans that vent into the attic instead of to the exterior, and window performance below current ENERGY STAR certification levels. Quality First Home Improvement addresses all five of these improvement categories.
Quality First Home Improvement serves Sacramento, Citrus Heights, Roseville, Rocklin, Elk Grove, Folsom, Davis, Concord, Walnut Creek, Pleasant Hill, Campbell, San Jose, CA, and Reno and Sparks, NV. 20+ years. 79,000+ homeowners served. GAF Master Elite Certified. Diamond Certified.
