[Equest-users] Effective Insulation/Farming Layer R-Value Value

Daniel Knapp via Equest-users equest-users at lists.onebuilding.org
Wed Jul 19 12:43:50 PDT 2017


I would just pick the R-value for insulation (21, 25?) that best matches the R-value of 4 inches of polyurethane spray foam. The depth of the cavity doesn’t make much difference to the end result. If the R-value you’re aiming for isn’t 21, or 25, just interpolate using the numbers in the table. Note that small differences in the R-value don’t make much difference to the effective R-value as thermal bridging has such a strong effect. 

—
Daniel Knapp PhD, P Phys, LEED AP
danielk at arborus.ca

Energy Efficiency Expert
Arborus Consulting
2-43 Eccles Street
Ottawa ON K1R 6S3
(613) 234-7178

> On Jul 19, 2017, at 10:16 AM, Morteza Kasmai via Equest-users <equest-users at lists.onebuilding.org> wrote:
> 
> There is a wall section in this project with 4” thick interior polyurethane spray foam inside the metal studs.
> Since Table A9.2B of ASHRAE 90.1 does not provide the effective insulation/framing layer R-Value for this type of insulation, how can one calculate this value?
> 
> Your thoughts and suggestions would be highly appreciated,
> Morteza
> 
> 
> 
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20170719/b4d2717a/attachment-0004.htm>


More information about the Equest-users mailing list