Renovated Home, Same High Bills? What a Renovation Misses and an Energy Audit Finds

The Short Answer

Most renovations change what you see: kitchens, bathrooms, floors, paint. Energy bills are driven by what you don’t see: air leaks, insulation levels and ductwork. Unless the project scope included air sealing and duct work, there is no reason the bill should drop, and some renovation work adds new leaks.

The way to find out is a professional energy assessment with a blower door test. It costs a few hundred dollars and tells you exactly where the house is losing heat, which is cheaper than guessing.

What Renovations Commonly Miss or Make Worse

• Recessed lights. Every can light in a top-floor ceiling is a hole into the attic. Green Building Advisor notes that can lights often end up displacing insulation and interrupting the continuity of the air control layer. Building Science Corporation’s attic guide calls for you to control air leakage through the ceiling light.
• New bathroom fans. A fan that dumps into the attic instead of outdoors moves moist air where it can cause damage. The same guide says bathroom fans must be vented to the outside prior to the attic being air sealed and insulated.
• Big kitchen range hoods. A powerful hood pulls air from wherever it can. Building Science Corporation’s guide notes that a powerful exhaust fan, such as a kitchen hood over 300 cfm, must be provided with adequate combustion or make-up air according to the building code.
• Disturbed ductwork. If walls or ceilings were opened, ducts may have been moved or disconnected. ENERGY STAR estimates that in a typical house about 20 to 30 percent of the air that moves through the duct system is lost to leaks, holes and poor connections, and that is before a renovation.
• The join between old and new. In an addition or a gut renovation, the connection between new framing and the original house is a classic place for gaps that disappear behind drywall.
• Insulation to code minimum. New work is insulated to what the code required at the time, which may be well below current recommendations, and existing attics are often left untouched.

What a Professional Energy Assessment Includes

The Department of Energy says that many professional energy assessments will include a blower door test and a thermographic scan, together with a room-by-room inspection and a look at past utility bills.

• Blower door test. A calibrated fan is fitted to an exterior door. The DOE explains that the fan pulls air out of the house, lowering the air pressure inside, so outside air rushes in through every leak. The readings let the contractor quantify the leakage before and after sealing.
• Infrared (thermographic) scan. A thermal camera shows missing insulation and moving air. The DOE notes that when done together with a blower door test, air leaks show up as black streaks in the infrared image. That is how hidden renovation gaps are found without opening walls.
• Duct leakage testing, if you have forced-air heating or cooling and the assessor offers it. Ask for it if the renovation touched the ducts.
• A combustion safety check on gas or oil appliances, which matters more after the house is tightened.

What It Costs and How to Find Someone

Angi puts the 2026 national average cost for a home energy audit at $437, with most homeowners paying between $212 and $698. A blower door test on its own runs $100 to $300 in the same guide. Many utilities subsidize assessments, so check your utility’s website first.

• BPI certified professionals. The Building Performance Institute certifies residential contractors and keeps a directory of certified professionals.
• RESNET HERS raters. RESNET’s HERS rater search lists member rating companies (not every rater), useful if you also want a rating for resale.

Ask for the blower door and infrared scan by name, and ask for a written, prioritized list of fixes.

Fix in This Order

1. Air seal. ENERGY STAR says contractors should seal air leaks in the attic floor before adding insulation, because it is much easier to seal first.
2. Ducts, if the test shows leakage or the renovation moved them.
3. Insulation. Bring the attic up to ENERGY STAR’s recommended level for your climate: R49 in zones 2 and 3 and R60 in zones 4 to 8 for an uninsulated attic.
4. Safety test. ENERGY STAR advises you to have a professional HVAC contractor conduct combustion safety testing after any air sealing.

Expect real but moderate gains. The EPA estimates that sealing and insulating can save an average of 15% on heating and cooling costs, or 11% of total energy costs. If your bill is still high afterwards, look at large loads such as a water heater, pool pump or electric heat, and at your rate.

Before You Call Anyone: A Quick Self-Check

You can get a head start in an evening. ENERGY STAR’s DIY checks include looking for daylight around doors and windows and moving an incense stick around common leak sites on a windy day. Check new recessed lights, outlets on exterior walls, the attic hatch and where new and old construction meet.

A whole-home energy monitor also helps: it shows whether the extra use is heating and cooling or something else running around the clock.

Frequently Asked Questions

Why are my energy bills still high after renovating?

Renovations usually change finishes, not the air sealing, insulation or ducts that drive heating and cooling costs. New recessed lights, exhaust fans and disturbed ducts can even add leaks.

What does a home energy audit include?

According to the Department of Energy, many professional assessments include a blower door test and a thermographic (infrared) scan, along with a room-by-room inspection and a review of past bills.

How much does a home energy audit cost in 2026?

Angi reports a national average of $437, with most homeowners paying $212 to $698. Many utilities offer discounted or free assessments.

How do I find a qualified energy auditor?

Look for a Building Performance Institute (BPI) certified professional or a RESNET HERS rater, and check whether your utility runs an assessment program.

Should I air seal or insulate first?

Air seal first. ENERGY STAR says contractors should seal attic air leaks before adding insulation, then have combustion safety testing done if you have gas or oil appliances.

Related Guides

• How much does an energy audit cost? — what to expect and what to ask for
• Attic air sealing cost — judging the quote you get
• How to find thermal leaks — the DIY version
• Best home energy monitors — finding what uses the power

Sources

• U.S. Department of Energy: Professional home energy assessments
• U.S. Department of Energy: Blower door tests
• U.S. Department of Energy: Home energy assessments fact sheet (PDF)
• ENERGY STAR: Duct sealing
• ENERGY STAR Home Upgrade: Attic insulation
• ENERGY STAR: Recommended insulation R-values
• ENERGY STAR: Methodology for estimated savings
• ENERGY STAR: DIY checks and inspections
• Building Science Corporation: Attic air sealing guide (PDF)
• Green Building Advisor: Recessed lights and air leakage
• Angi: Home energy audit cost (Oct 2026)
• Building Performance Institute: Homeowner benefits
• RESNET: Find a HERS rater