F-Factor Calculation - ASHRAE 90.1-2007 Table A6.3
Does anyone know what the two different columns for unheated and heated slabs represent in Table A6.3 ? Why are there different F-Factors for the same horizontal insulation distance and the same R-value? The example below that is highlighted is that if I have a slab with 12 inches of R-5 horizontal insulation is the F-Factor 0.72 or 0.61?
Does anyone know the basis of this table?
These values come from work David Baylon and Mike Kennedy did for the state of Washington. See this publication for more background.
Hhhmmm. That's interesting. These numbers are somewhat lower than those in my 1988 paper. I guess I'll have to read the Baylon paper to find out how he and Mike got the F-Factors. I just did a regression of the fluxes to the Inside-Outside Air Temp Difference, so the F-Factors can vary depending on location.
I fixed the broken link for Neal's comment above.