Blower Door Tests
A blower door is a powerful fan that mounts into the frame of an
exterior door. The fan pulls air out of the house, lowering the
air pressure inside. The higher outside air pressure then flows
in through all unsealed cracks and openings. The auditors may use
a smoke pencil to detect air leaks. These tests determine the air
infiltration rate of a building.
Several reasons for establishing the proper building tightness
- to reduce energy consumption due to air leakage;
- to avoid moisture condensation problems;
- to avoid uncomfortable drafts caused by cold air leaking in
from the outdoors; and
- to make sure that the homes air quality is not too contaminated
by indoor air pollution.
There are two types of blower doors: "calibrated" and
"uncalibrated". It is important that auditors use a calibrated
door. This type of blower door has several gauges that measure the
amount of air pulled out of the house by the fan. Uncalibrated blower
doors can only locate leaks in homes. They provide no method for
determining the overall tightness of a building. The calibrated
blower doors data allows the auditor to quantify the amount
of air leakage and the effectiveness of any air-sealing job.
Energy Audits, EREC Reference Briefs, Office
of Energy Efficiency and Renewable Energy, US Department of