Retrotec USACE - Manual (Page 300)

F6 ENERGY & PROCESS ASSESSMENT PROTOCOL
TABLE F3. RANGES OF ERROR FOR RESULTS OF TESTS PERFORMED UNDER
TYPICAL WEATHER CONDITIONS AT DIFFERENT TEST PRESSURES
Test pressure direction Maximum error
75 Pa Pressurize +/– 5%
50 Pa Both Ways +/– 5%
50 Pa Pressurize +/– 7.5%
25 Pa Both Ways +/– 10%
25 Pa Pressurize +/– 15%
20 Pa Both Ways +/– 15%
20 Pa Pressurize +/– 20%
12.5 Pa Both Ways +/– 20%
12.5 Pa Pressurize +/– 30%
The difference in pressurized and depressurized is due to external venting
fl aps that will open under pressurizing but will attempt to seal under depres-
surization. Since bias pressures can be created by a zero shift in the case of
stack pressures or it can be created by a fl ow causing a pressure drop, it is
inaccurate to simply subtract bias pressures since they may not be additive.
Regardless of how these bias pressures are formed, it can be shown that they
cancel out very well no matter how they were created if testing is performed in
both directions and then averaged.
Specifi cations for high rise building tests often cite “ASTM E779-03 Stan-
dard Test Method for Determining Air Leakage Rate by Fan Pressurization”
but it is not really suitable for high rise building testing without some modi-
fi cations. It was originated to test houses with a result at 4 Pa. Since ambient
pressure fl uctuations on the house due to stack and wind could be close to 4 Pa
making measurements inaccurate, ASTM stated that preferred test conditions
are “4 mph wind or less and a temperature range of 41 to 95 F”. Since these
requirements would make testing prohibitively expensive due to these me-
teorological restrictions, fi eld testing devolved into testing at 50 Pa which had
the advantage of being repeatable. If ASTM needs to be modifi ed for houses,
an even more robust protocol is required for high rise buildings because bias
pressures can be fi ve times higher than those found in houses. ASTM E1827,
CGSB 149.10, ATTMA TS-1 and EN13829 suffer from the same type of prob-
lems since they were not really intended for the testing of high rise buildings.
What is needed for high rise testing is a more robust procedure that
acknowledges that tests will be performed over a wide range or weather
conditions.
Recommended Test procedures specifi ed below were developed by the
US Army Corps of Engineers in collaboration with industrial partners: Retro-
tec Energy Innovations, Canada; Professional Investigative Engineers (PIE),
USA; BCRA, USA; and Camroden Associates, USA to achieve meaningful and
repeatable results on high rise commercial and residential buildings.