How do I calculate the U-factor for the construction assembly (e.g walls) according to ASHRAE 90.1-2007 Appendix A if one or some of the construction layers properties are not specified in the mentioned appendix?
I'm trying to calculate the assembly U-factor of a wall which have the following construction layers: Plaster, Common brick, Airspace, Low weight concrete block, Plaster, Airspace and finally Marble.
I found that common brick and marble thermal properties are not specified in appendix A so, which path should I follow? Can I take the values showed in any other reference?
Thanks in advance
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5906 thumbs up
May 31, 2012 - 2:50 pm
Appendix A includes an assumed wall construction including indoor and outdoor surfaces. If your wall deviates thermally (not just different materials) and the material in question is continuous then simply add the material to the Appendix A value. I would recommend the use of the values from the ASHRAE Handbook.