Whole-Wall Thermal Performance: Airtightness
A combination of ASTM Standards (C236 or C976 [ASTM 1989]) or E1424 and E283 (ASTM
1995) will be used to measure the air leakage and heat loss through wall assemblies under
simulated wind conditions ranging from 0 to 15 mph (24 kph). Varying the differential pressures
from 0 to 25-50 Pa should simulate the extremes to which a wall is exposed in a real building.
However, because many of the leakage paths through an exterior wall of a residential building
occur at the wall connections and not through the typical clear wall, comprising the 8-ft by 8-ft
(2.4-m x 2.4-m) test section, the test specimen will be modified to contain one light switch and
one duplex outlet connected with 14-gauge wiring and possibly other details. With heat loss in a
building reaching as high as 40 % due to infiltration (NAIMA 1994), including this performance
parameter would be important, but the workmanship quality on the construction site compared to
a laboratory specimen must be considered. A second complicating factor is that, over time,
materials may shrink, crack etc., and this will change the leakage over time. Procedures to
measure this wall performance element are not as well developed as the first two and will need to
be verified.
For more information, contact the program manager for Building Envelope Research:
André O. Desjarlais
Oak Ridge National Laboratory
P. O. Box 2008, MS 6070
Oak Ridge, TN 37831-6070
E-mail Andre Desjarlais
Revised: May 26, 2004 by Juanita Denton