If you've noticed your HVAC system running constantly, uneven temperatures room to room, or energy bills that seem higher than they should be, there's a good chance your home has an air leakage problem.
The short answer to whether sealing air leaks reduces energy bills is yes, often significantly. But understanding why requires a closer look at how your home actually loses energy and what a blower door test reveals about your building envelope.
Your heating and cooling system works to maintain a consistent indoor temperature. Every time conditioned air escapes through gaps, cracks, and penetrations in your home's envelope, your HVAC system has to work harder to replace it. That's energy you're paying for that never actually keeps you comfortable.
Common air leakage points include areas around windows and doors, electrical outlets and switch plates on exterior walls, recessed lighting fixtures, plumbing and electrical penetrations, the attic hatch or pull-down stairs, rim joists and band boards in the basement or crawlspace, and HVAC register boots. Most homeowners are surprised to learn that the cumulative effect of these small leaks can equal leaving a window open year-round.
A blower door test measures exactly how much air your home leaks under controlled conditions. During the test, a calibrated fan is mounted in an exterior door frame and depressurizes the house to a standard pressure difference (typically 50 Pascals). The fan measures how many cubic feet of air per minute (CFM50) are flowing through leaks in the building envelope.
This measurement is then converted to air changes per hour at 50 Pascals (ACH50), which gives you a standardized way to compare your home's air tightness against building codes and energy efficiency benchmarks.
For context, IECC 2018 energy code requires new homes in Tennessee to achieve 3 ACH50 or better. Older homes in Middle Tennessee often test at 8, 10, or even 15+ ACH50, meaning they're exchanging their entire air volume with outside air multiple times per hour under pressure.
When you reduce air leakage, several things happen. Your HVAC system runs less frequently because it's not constantly replacing lost conditioned air. Temperature stays more consistent throughout your home because you're not pulling in hot air in summer or cold air in winter through random gaps. Humidity control improves because you're not introducing outside moisture (or losing indoor humidity in winter). Your equipment experiences less wear because it's cycling less often.
The Department of Energy estimates that air leakage accounts for 25-40% of the energy used for heating and cooling in a typical home. Even conservative air sealing improvements often yield 10-20% reductions in heating and cooling costs.
While lower utility bills get the most attention, many homeowners find that comfort improvements matter even more. Drafty rooms become livable. That bathroom that was always cold in winter finally feels normal. The upstairs bedroom that baked in summer stays cooler.
Air sealing also improves indoor air quality by giving you more control over where air enters your home. Instead of pulling unfiltered air through gaps in your walls and attic, you're bringing air through your HVAC system where it can be filtered and conditioned properly.
Here in Middle Tennessee, we experience both heating and cooling seasons, which means air leakage costs you money year-round. Summer humidity makes leaky homes feel muggy and forces AC systems to work overtime on dehumidification. Winter temperature swings, where we might see 60°F one day and 30°F the next, create pressure differentials that drive air movement through every gap in your envelope.
Homes in Nashville, Franklin, Murfreesboro, Gallatin, and throughout the region deal with these conditions constantly. The tighter your building envelope, the less your comfort depends on what the weather is doing outside.
The most effective approach to air sealing starts with testing. A blower door test identifies not just how leaky your home is, but where those leaks are located. Combined with thermal imaging, which shows temperature differences that indicate air movement, you get a clear picture of where to focus your sealing efforts.
This matters because air sealing materials and labor aren't free. You want to prioritize the biggest leaks first, and you want to verify that your work actually improved the envelope. A follow-up blower door test after sealing confirms your results and quantifies the improvement.
A standard blower door test takes 30-60 minutes. You'll receive a report showing your home's CFM50 and ACH50 measurements, along with identification of major leakage areas. For homeowners considering air sealing work, this information helps you get accurate quotes from contractors and set realistic expectations for improvement.
For new construction, blower door testing is required for code compliance in Tennessee. For existing homes, it's the most accurate way to diagnose comfort and efficiency problems and measure the effectiveness of upgrades.
Middle Tennessee Blower Door provides RESNET-certified blower door testing for homeowners and builders across Davidson, Williamson, Rutherford, Sumner, Wilson, and surrounding counties. Owner Chris Lewis brings over 20 years of construction experience to every inspection.
Tests start at $300. Same-day scheduling available.
Call or text (615) 613-5447 to schedule your test, or visit middletennesseeblowerdoor.com to learn more.