Blower door testing uses a powerful fan, inserted into the frame of an exterior door or window, to measure the air-tightness of a building. It works by lowering the air pressure of the home and measuring the amount of outside air that leaks through - determining the air infiltration rate. The air infiltration rate can then be used in conjunction with volume calculations to determine your homes air change per hour.
The goal is to have as little infiltration as possible, indicating an airtight, well sealed home. An airtight home is important for:
Reducing energy consumption
Avoiding moisture condensation problems
Preventing uncomfortable drafts
Determining proper ventilation for acceptable indoor air quality
Duct leakage testing uses a pressurizing fan connected to a branch of the ductwork to measure the air-tightness of the homes' HVAC system and will assist in determining the level of air leakage during heating and cooling operation.
Studies have shown that duct leakage can account for as much as 25% of total house energy loss, sometimes having a greater impact on energy use than air infiltration through the building. Leaky ducts:
Disperse expensively conditioned or heated air outside of the main house
Create moisture and uncomfortable humid environments
Can carry dust, mold, and other contaminants from unconditioned environments