[Greenbuilding] Slab heat loss calculation
nick pine
nick at early.com
Sat Aug 24 04:44:42 CDT 2013
RT <archilogic at yahoo.ca> writes:
>... In putting our pants back on frontwards, someone noticed that we had
>all received tattoos onto our backsides:
>
> ? ? ? ? ? "? q? =? A [ dT ( K/s + hc ) +? ( ? * T^4 ) ]? "
How do you estimate slab heat loss?
After lots of finite difference network ground loss calculations Professor
Kelly Kissock at U Dayton
http://academic.udayton.edu/kissock/http/EEB/Energy%20Efficient%20Buildings_1.htm
says an A ft^2 slab on US Rf foamboard with Rp vertical perimeter insulation
down "to the footer" would have an approximate
A(0.1140/(4+Rf+Rp)+0.8768/(16+Rp)) Btu/h-F conductance from the room air
temp to the 4 meter deep ground temp.
For example, a 900 ft^2 slab on R10 foamboard with R15 perimeter insulation
would have a 900(0.1140/(4+10+15)+0.8768/(16+15)) = 29 Btu/h-F conductance
from a 65 F room air temp to a 58 F deep ground temp, so the room would lose
(65-58)29 = 203 Btu/h to the slab.
How much would this change with different perimeter insulation depths?
Nick
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