For a building with a 200 ft × 100 ft slab on grade floor made up of 4-in. concrete floor:

a. Estimate the annual energy ground-coupled loss/gain from the building located in Denver, Colorado.

b. Estimate the annual heating energy use savings if the slab is insulated uniformly with R-10 rigid insulation. Assume a furnace efficiency of 85 percent.

c. Implement the calculation procedure for slab-on-grade floor heat loss in a spreadsheet and determine if there is an optimal cost-effective insulation level (i.e., R-value) for the foundation. Assume that the fuel cost is

$10.0/MMBtu, the efficiency of the heating system is 0.80, the cost of adding insulation is 0.5 per ft2 of R-5 rigid insulation, and the discount rate is 5 percent.