Retrotec USACE - Manual (Page 310)

F16 ENERGY & PROCESS ASSESSMENT PROTOCOL
A rough estimate as to whether the enclosure could pass, which may force 2.
the testing agency to spend more time investigating enclosure problems,
instead of using time to verify an obvious failing enclosure.
For the preliminary test:
Record interior and exterior weather conditions 1.
Record average and maximum wind speed and direction at least 5-feet 2.
(1.5 m) off the ground and 25-feet (7.5 m) away from the building in the
direction of the wind.
Record interior and exterior temperatures before and after the test.
3.
Record site elevation in feet above sea level. 4.
Perform a multi-point test in both directions from at least + 25 to + 50 Pa, 5.
then - 25 to - 50 Pa.
Because this test is performed by pressurizing and depressurizing the air barrier
envelope, bias pressure effects are minimized, yielding more accurate results.
This is the preferred test method since it is not only more tolerant of test con-
ditions, but also gives a more accurate representation of the envelope leakage
under ambient conditions, where pressures can be either positive or negative
in direction. Bias pressures may be up to 30 percent of the lowest test pressure,
allowing this method to be used in a wider range of weather conditions. If fan
power is suffi cient, then testing up to 75 Pa would be even more accurate and
would allow tests to be completed where bias pressures were higher.
The testing agency must achieve at least 50 Pa, but there is no requirement
that it must achieve a maximum pressure of 75 Pa. The agency is encouraged to
achieve the highest building pressure possible, but should not exceed 75 Pa.
It is noted that some buildings will have air barrier systems that have not
been properly designed and/or installed, resulting in the maximum building
pressure being less than 50 Pa. Although the building does not meet the air
leakage requirement (e.g., of 0.25 cfm/sq ft, (1.27 L/s*m
2 ) the testing agency
must still perform a multi-point test in general accordance with this protocol so
an approximate air leakage value can be provided to the prime contractor. This
will allow them to estimate the magnitude of the repairs necessary to meet the
air leakage requirement.
F.9.7 Reporting of Results
The data collected during the multi-point tests will be corrected for standard
conditions and used to determine the air leakage coeffi cient, C, and the pres-
sure exponent, n, in accordance with ASTM E779-03, from:
CFM
⫽ C * P n
In general, the C and n values are obtained by plotting the data in log-linear-
ized fashion to obtain a curve fi t that will produce the required coeffi cients.
The testing agency must use a minimum of 12 data points from each test, but