Retrotec USACE - Manual (Page 312)

F18 ENERGY & PROCESS ASSESSMENT PROTOCOL
“tight” residential homes exhibit an n value of 0.60 to 0.65, where larger build-
ings will likely have an n value slightly less.
The testing agency is required to produce the data used in the analysis and
results in tabular and graphical form, including the curve fi tted coeffi cients and
correlation coeffi cient.
Several common conditions that will cause test results to be very low are:
Interior pressure monitoring stations are placed too close to direct air 1.
fl ow that is typically produced by the test fans.
Usually tests are conducted with the fan orifi ce fully open, allowing
2.
maximum airfl ow. For testing smaller envelopes that require smaller
test fl ows, a fl ow restriction device such as a plug or plastic ring can be
installed on the fan. When limiting the fan air fl ow, the gage manufac-
turer requires that the digital gage’s confi guration be adjusted. If the
gauge is incorrectly set on a lower range than the fan, then the measured
fl ow will be much lower than the actual fl ow.
Interior doors have been left closed.
3.
Exterior envelope is very tightly sealed. 4.
Several common conditions will cause results to be very high are:
Intentional openings have not been properly sealed or have opened 1.
during the test (i.e., pressure relief dampers, plumbing traps).
Windows or exterior doors are left open.
2.
HVAC equipment is not properly disabled. 3.
If the gauge is set on a higher range than the fan, then the measured 4.
fl ows will be much higher than the actual fl ow.
It is possible the building contains signifi cant holes in the air barrier
5.
enclosure and the high readings are simply an indication of the perfor-
mance of the building.
F.9.8 Locating Leakage Sites with Pressurization
and Depressurization
If the building fails the test, it is important to determine the source of the air
leakage. It is also benefi cial for the design-build team to understand the loca-
tions and details that are susceptible to leakage, even if the building as a whole
passes the test. The testing agency is required to perform a diagnostic evalua-
tion in accordance with ASTM E1186. The testing agency can use additional
methods to discover leaks.
Neutral buoyancy smoke, theatrical smoke and infrared (IR) are effective
means to fi nd leakage sites. When testing equipment pressurizes the enclo-
sure, air leaks can be seen from outdoors (provided exterior walls have not
been heated by radiation from the sun) using infrared thermography or large
scale smoke generation. When testing equipment depressurizes the enclosure,