Testing a Property’s Building Envelope For Infiltration

Specialized building inspectors utilize a device called a “Blower Door” to assess and aid in the buildings air tightness.

Benefits resulting from an air tight structure include:

  • Reducing energy usage attributed to air leakage.
  • Avoiding humidity or moisture build-up causing water condensation problems.
  • Avoiding unpleasant drafts created by cool air leaking in by way of the outdoor environment.
  • Making certain that the properties air quality is properly ventilated.

How They Work

A “Blower Door” is a strong fan that mounts directly into your exterior doors framework.  The fan draws air out of the building, decreasing the air pressure inside. The greater outdoor air pressure enters the building by means of unsealed crevices and voids in walls, windows and ceilings. The inspectors use a smoke pencil to help discover air flow leaks.  Such assessments verify the air infiltration rate for a building.

“Blower Doors” are constructed of a framework and adaptable section which fit within a doorway.  A variable-speed fan and pressure gauge determine the pressure differences indoors as well as exterior to the property, and an airflow manometer and tubes are used to gauge airflow.

There are two kinds of blower doors: calibrated and uncalibrated. It is essential that auditors make use of calibrated Blower Door Units. This particular type of blower door features numerous gauges which assess the quantity of air drawn out of the building through the fan. Uncalibrated blower doors will simply identify leaks in properties. The uncalibrated units offer no method for analyzing the over-all air tightness of the building. The calibrated blower door’s information permits the inspector to assess the quantity of air leakage as well as the success of any air-sealing work.

Planning for a Blower Door Test

Complete the following measures to get your property ready for a blower door test:

  • Close windows and open up inside doors.
  • Turn down your thermostats for heating units as well as water heating units.
  • Cover ashes in wood stoves and fire places with moist newspapers.
  • Shut fireplace dampers, fireplace doors, and wood stove air intakes.

A Blower Door test and the resulting sealing of the building envelope will return energy savings for years to come.