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Blower Door Infiltration Testing


Basic methodology:  

Blower Door Infiltration Testing:  

Blower door infiltration testing consists of connecting a blower fan to pressurize the building to a known pressure.   By measuring the flow of the air through the fan, we know the amount of leakage in through the envelope of the home.  This is based on the principle that, if pressure is stable within a system, then the amount of air entering and exiting the system must be equal. If more air is entering than exiting, the pressure will rise.  If more air is exiting than entering the system, the pressure will drop.   By measuring the total leakage of the building envelope we can determine the necessity of air-sealing to minimize energy waste, or the necessity of mechanical ventilation to maintain a healthy indoor environment.  This test is also required by the current energy codes.   The 2009 IECC (International Energy Conservation Code) requires a home to be better than 7.0 ACH50 (Air changes at 50 pascals of pressure difference between the home and the exterior).   The 2009 IECC is the standard used in Pennsylvania. Maryland has adopted the 2015 IECC which requires a home to be better than 3.0 ACH50.   


To prepare for this test we perform the following steps:

  1. Close all windows.
  2. Open all interior doors.  
  3. Close all exterior doors, and all doors to unconditioned spaces like a basement or crawlspace.
  4. Turn off all mechanical exhaust fans.
  5. Turn off the HVAC, and turn off all combustion appliances.
  6. Close fire-place and stove dampers, and close the doors to same.  

Note:  If pulling insulation or ashes into the home is a concern, it is advisable to pressurize the home rather than using depressurization.   

Additional Testing:

In addition to measuring total leakage with the blower door, we can help you to diagnose specific leaks through the use of various tools such as smoke pencils, thermal imaging, and simply feeling for leaks while the blower door fan is running.   Zone-pressure diagnostics is a method that allows us to determine relative leakage from different areas by opening and closing doors.