When homeowners or builders in Nashville hear about a blower door test, one of the first questions they ask is simple: how does it actually work? The process may look complicated with the equipment set up at your front door, but the idea behind it is straightforward.
For every test, I bring a calibrated blower door fan, an adjustable frame with a nylon panel, and digital pressure gauges. The frame seals into an exterior doorway, and the fan is designed to either pull air out of the home (depressurize) or push air in (pressurize). The gauges record how much airflow is required to maintain a set pressure difference between the inside of the home and the outside.
By creating that pressure difference—typically 50 Pascals—we can simulate wind pushing against the home. The equipment then measures how quickly air sneaks through leaks, cracks, and gaps in the building envelope. From these readings, we calculate a number known as ACH50 (Air Changes per Hour at 50 Pascals), which tells us how many times the air inside the home is replaced with outside air in one hour.
A lower leakage rate means a tighter home, which is good news for comfort, energy bills, and meeting code requirements. In Middle Tennessee, many municipalities require blower door testing for new construction to verify energy efficiency. For builders, a passing score is often the final step before inspection approval. For homeowners, the results highlight where improvements like sealing or insulation could save money and improve indoor air quality.
In short, blower door testing doesn’t just involve fancy equipment—it provides a clear picture of how well a home is sealed against the elements. Whether you’re a contractor needing documentation for code officials or a homeowner curious about energy efficiency, the test answers one simple question: how leaky is your home, and what can you do about it?