Helow all,
In this LEED-CS project, the existing masonry wall was changed to the
following configuration (from outside to inside):
- glass-fiber-reinforced concrete panels [TAKTL] on galvanized steel
furring channels
- existing 8" masonry wall
- 3" polyisocyanurate insulation (R-18)
- 1/2" air space
- 3-5/8" metal studs without thermal insulation
- 5/8" gypsum wall board
Per ASHRAE 1.4 Tables ?Opaque Building Envelope Constructions? requirnment,
proposed construction assembly U-factor should be as-designed and
consistent with Appendix A of ASHRAE 90.1. I cant fined any table in
Appendix A to match this configuration. How should I select the U-factor
for this wall?
Thank you so much for your help,
Morteza
Hello Morteza,
Here is a catalog of tested wall masonry assemblies, you may be able to
find most of your assembly in it. I do not guarantee the accuracy of the
data nor the testing procedures used to obtain it as you will see they
did not mention the use of any ASTMs. However, it may be helpful
calibration data if you need to build an isothermal or 2-D model of your
wall assembly.
Also ASHRAE 90.1-2007 Section A9 lists the procedures to determine
assemblies that are not listed in the tables of Appendix A. Reading
between the lines a little you can calculate the R-Value for each layer
using the appropriate calculation method for that type of wall. For
example you can use the test data for the exterior CMU wall layers and
do a parallel path calculation for the continuous insulation and cavity
layers, sum the results for the assembly R-Value.
Hope that helps,
Byron D. Burns, EIT, BEMP
Hi Byron,
This is very helpful, thank you very much for your comment.
My Best,
Morteza