The Blower Door is a diagnostic tool designed to measure the air tightness of buildings and to help locate air leakage sites. Building air tightness measurements are used for a variety of purposes including:
Documenting the construction air tightness of buildings
Estimating natural infiltration rates in houses
Measuring and documenting the effectiveness of air sealing
Measuring duct leakage in forced air distribution systems
Experience has taught us that these same areas where your house is “leaky” are conducive to Rodent (mice and rat) and Nuisance Wildlife entry. The critters feel the warm air leaving your home and are drawn to the gap or hole where the warm air is coming from. They will fight hard to access the inside of your home once they have a strong enough desire to do so. With their survival instincts in full swing during winter months, they will go as far as damaging in your home to get inside.
The Blower Door consists of a powerful, calibrated fan that is temporarily sealed into an exterior doorway. The fan blows air into or out of the building to create a slight pressure difference between inside and outside. This pressure difference forces air through all holes and penetrations in the exterior envelope. By simultaneously measuring the airflow through the fan and its effect on the air pressure in the building, the Blower Door system measures the air tightness of the entire building envelope. The tighter the building (e.g. fewer holes), the less air you need from the Blower Door fan to create a change in building pressure.
Most people notice air leaks in the winter and refer to them as “drafts”. Most noticeable air leaks (drafts) are around windows and doors. You may feel these leaks and think that they are probably the your major source of wasted energy. However, in most homes the most significant air leaks are hidden in the attic and basement. These leaks are typically the most significant factor in energy waste and making your house uncomfortable. Locating these leaks can be difficult because they are not always easily felt as you would a leak around a window or door. By having a blower door test done, the technician will be able to easily find the “harder to find” air leaks in both your attic and your basement.
Having an attic with a lot of air leaks will cost you a lot in energy waste. In the cold weather, the warm air rises in your home, just like it does in a chimney. This air, which you have already paid to heat rises up into your attic and sucks cold air in all around your home – window, doors and through holes in the basement.