Why Colorado Homes Struggle with Energy Loss and How Blower Door Testing Can Help

Ever wonder what our energy techs are doing when they show up with a giant fan? It’s for blower door testing – a useful way to find where a home is losing energy. So let’s walk through what happens during the test, why it matters in Colorado, and what we do when we find a problem.

What Happens During Blower Door Testing

First, our tech seals a calibrated fan into your exterior door frame using an adjustable panel. The fan then pulls air out of the house. That drops the indoor air pressure below the pressure outside. This pressure difference forces outside air to rush in through any gaps, cracks, and unsealed penetrations in the building envelope.

While the fan runs, we can use a thermal camera to trace where that air is entering. That way, if sealing is needed, we know exactly the areas to address. 

The results for a home that passed its blower door test.

The test also produces a number: your home’s air changes per hour, or ACH. That figure tells you how many times your home’s entire air volume gets replaced with outside air in an hour. Lower is better. It also gives us a baseline to compare against after any sealing work.

Why Older Colorado Homes Struggle with Energy Loss

A lot of Front Range subdivisions were built decades ago. Insulation and air-sealing standards back then were nowhere near what they are today. Updated IECC standards have changed. Homes built before the 1990s often have minimal attic insulation and almost no attention paid to air sealing. Builders back then focused on keeping water out, not air.

That gap shows up fast on a blower door test. We regularly see leaky attic hatches in homes from this era. Gaps around recessed lighting and rim joists with zero insulation are just as common. Older homes can also have leaky ductwork running through unconditioned crawlspaces, which makes things worse. 

What Inspectors Typically Find During A Blower Door Test

If the blower test decks energy loss, poorly sealed windows are one of the most likely places to look.

In our experience, four leak points show up again and again: 

• Attic hatches
• Recessed can lights
• Rim joists
• Poorly sealed window/door frames 

Colorado homes built before 1990 often show air leakage 20 to 30% higher than a comparable newer home. Simple sealing work can bring that number down, sometimes by half.

What Happens If We Find a Problem

A blower door test turning up serious leakage isn’t where the conversation ends. Our Shield Warranty Program includes Energy Shield coverage. If we perform an Energy-Check with your inspection and later find insulation deficient in visible areas, our team will help cover part of the cost to fix it. 

And if questions come up after your inspection, our Ask Your Inspector program has you covered. You can follow up directly with your inspector by chat or email instead of starting over with someone new.

Ready to Find Your Home’s Leaks?

A blower door test gives you real data instead of a guess about why your energy bill feels high. Curious what’s happening behind your own walls? Check out our air leakage and blower door testing service to schedule one.

Frequently Asked Questions

How long does a blower door test take? 

Most single-family homes take about 1 hour. That includes setup, the depressurization test, and time spent tracing leak locations.

Is a blower door test the same as a HERS rating? 

No, but they’re related. A blower door test measures air leakage specifically. A HERS rating uses that data, plus insulation and HVAC performance, to score overall home efficiency.

Can a blower door test damage my home?

No. The pressure difference stays well within safe limits. It doesn’t stress the structure or its systems.

Do older Colorado homes always fail a blower door test? 

Not necessarily fail, but they often show higher air leakage than newer construction. That’s expected given older insulation and air-sealing standards. It’s exactly what the test is designed to catch.