Hello,
I am trying to build my proposed and my baseline building in equest.
My problem is that for the structure element " floor on slab" I need to Input the Uvalue.
In ASHRAE 90.1.2010 in table 5.5.3 for this structure element the F- factor is given in Βtu/(h ft F).
Do you know the relation between the Uvalue and F-factor?
Thank you very much
Paula Melton
Editorial DirectorBuildingGreen, Inc.
LEEDuser Moderator
183 thumbs up
November 6, 2018 - 12:08 pm
Hi, Konstantina! Wondering if this thread might help: https://leeduser.buildinggreen.com/forum/u-value-f-factor
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
November 6, 2018 - 12:25 pm
Slabs are usually insulated around the edge, both in under the slab and down along the outside. The F-factor accounts for the edge treatment since this is where most of the heat loss occurs. Think of it like a whole assembly U-value of sorts. Some software like eQUEST uses this value. A U-value can be used in software where the F-factor is not used. Just apply the U-value to the correct areas of the slab.
So there is no direct relationship where you can convert one to the other.
The F-factor can be derived from 90.1-2010 Appendix A - see Section A6 and Table A6.3 for additional guidance.