What is a Blower Door. The Blower Door is a diagnostic tool designed to measure the airtightness of buildings and to help locate air leakage sites. 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 different between inside and outside. The pressure created simulates 20 mph. winds on all four sides of the building. 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, this test measures the airtightness of the entire building envelope. The tighter the building (e.g. fewer holes), the less air you need from the fan to create a change in building pressure. Blower Door tests can be used for a variety of purposes including: • Locating direct and indirect air leaks. • Documenting the construction airtightness of buildings. • Estimating natural infiltration rates in houses. • Measuring and documenting the effectiveness of air sealing activities. • Measuring duct leakage in forced air distribution systems. • Determining the need for ventilation equipment. In addition to assessing the overall airtightness level of the building envelope, the Blower Door can be used to estimate the amount of leakage between the heated space of the building and the attached structural components such as attached garages, attics and crawlspaces. It can also be used to estimate the amount of outside air leakage in forced air duct systems. And because the Blower Door forces air through all holes and penetrations that are connected to the outside, those problem spots are easier to find using chemical smoke, an infrared camera or simply feeling with your hand. These air leakage paths are found and then documented by the auditor to provide recommendations and solutions for air sealing work. For more info on air leakage Click Here. (enter air leakage text provide for new web page)