Retrotec Blower Door - Manual (Page 45)

Page 45 of 87
©Retrotec Inc. 2015
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4.15 Basic Results from Single Point Test
Basic test results from a single-point test can be used to provide a simple and quick assessment of a building's
airtightness. The DM-2 digital gauge is capable of displaying most common calculations directly on the screen as the
measurements are being made.
4.15.1. Air Leakage at 50 Pascal
The industry standard measurement is CFM50. This is the airflow (in cubic feet per minute) required by the Door
Fan to create a pressure difference, between the building interior and the outdoors, of 50 Pascals. This difference is
roughly equivalent to the pressure that the building experiences in a 20 mph wind.
4.15.2. Air Changes per hour at 50 Pa - ACH50
ACH50 is the number of complete air changes that will occur in one hour, when a building pressure of 50 Pascals is
applied across the building envelope. The value is calculated based on the volume of the enclosure, so it is a useful
method of normalizing leakage rate.
4.15.3. Equivalent Leakage Area - EqLA 10
Equivalent leakage area is defined as the area of a hole in a thin panel that would leak the same amount of air as the
building does at a pressure of 10 Pa with reference to the outdoors. (Discharge coefficient of 0.61)
4.15.4. Effective Leakage Area - EfLA 4
Effective Leakage Area calculation is defined as the area of the elliptical nozzle-shaped hole that would leak the
same amount of air as the building does at a pressure of 4 Pa with reference to the outdoors. (Discharge coefficient
of 1.0)
4.16 Results from Multi-Point Procedure
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