Masonry Magazine July 2011 Page. 30
THERMAL MASS
To identify mass walls for compliance with Table 13-1 and 13-2, use the heat capacity values directly from code Table 10-9 or other recognized sources. Cavity walls have been included.
Summary
The masonry (mass) wall requirements of the new Oregon and Washington state energy codes have not changed. Most common concrete masonry wall systems will qualify as "mass walls" meeting the wall weight or heat capacity provisions of these codes. They are eligible to comply with the codes using the lower mass wall requirements in the prescriptive compliance tables. There are a variety of masonry wall types and insulation options available for code compliance. Single-wythe walls can be insulated as shown in Figure 2.
Table 3-Washington Building Envelope Requirements - Nonresidential Mass Walls
Climate Zone I
Climate Zone 2
U-0.150 or R-5.7 continuous insulation
U-0.123 or R-7.6 continuous insulation
1 Nonresidential walls may be ASTM C90 concrete block walls, ungrouted or partially grouted at 32 inches or less on center vertically and 48 inches or less on center horizontally, with ungrouted cores filled with material having a maximum thermal conductivity of 0.44 Btuin/h-ft2-F.T
Regardless of a project's energy efficiency and sustainability design goals, concrete masonry walls can help to meet these goals. In addition to the thermal mass benefits discussed in this article, concrete masonry is a locally produced construction material that has superior durability minimizing the need for repair or replacement. It also provides aesthetic appeal, structural strength and resistance to fire. IMAS
INTERIOR
INTEGRAL
EXTERIOR
Figure 2-Insulation Options with Concrete Masonry Single-Wythe Walls
Tom Young, P.E, is the executive director of the Northwest Concrete Masonry Association. He has worked for the masonry industry for more than 35 years and serves on numerous code development and technical committees.
This article first appeared in MASONRY, a publication of the Masonry Industry Promotion Group in Spokane, Wash.