Problem:
How much heating load (TU per year) would be saved by changing the exterior wall of a 20,000 if building from 1" stucco + 8"HW concrete block to 1" stucco + 2" insulation + 4" common brick? Assuming the building is located in a region with 4 months of winter with the outside temp of 10 and inside temp of 75? If the energy cost is $6.50 per million btus what is the average savings?
Note: Provide support for your underlying principle.