This article discusses the conductive Heat loss calculations that affect HEAT's walls, attics, windows and doors and basement/floor screens.
The calculations for the adjusted Rvalues after selecting a framing option are done in UValues which are the reciprocals of RValues, U=1/R.
For the annual heating season, conductive heat loss through walls, ceilings, windows, doors, and floors uses the following calculation:
Where n = the discrete temperature bin midpoint (in 5 degree intervals) for all bins under 60^{o}F; h = hours at each temperature annually, U = Uvalue of the buildings component, and A = the area.
For annual cooling season conductive heat gain through walls, Attics, windows, doors, and floors:
Where n = the discrete temperature bin midpoint (in 5 degree intervals) for all bins over 80^{o}F; h = hours at each temperature annually, U = Uvalue of the buildings component, and A = the area.
Uvalues that are used in the bin analysis are generated using assembly Uvalue methodology by generating a material weighted Uvalue for each shell component. An example calculation for a wall is as follows:
Example for an R 13 insulated 2x4 stud wall with wood siding 


Rvalue 


Building Component 
stud 
cavity 

outside air film 
0.17 
0.17 

wood siding 
0.8 
0.8 

plywood sheathing 1/2" 
0.63 
0.63 

3 1/2" stud 
4.38 
13 

1/2" drywall 
0.45 
0.45 

inside air film 
0.68 
0.68 







percent of wall area 
0.15 
0.85 

total wall component rvalue 
7.11 
15.73 

wall component uvalue 
0.141 
0.0636 

total wall assembly uvalue 


0.075 
total wall assembly rvalue 


13.3 
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