A house located in Denver, CO, has R-11 walls (1,650 ft²), R-19 ceiling

(2,000 ft²), and R-2 windows (200 ft²). Assume that the infiltration/ventilation rate is 0.75 ACH.

a. Estimate the annual fuel energy use and cost savings for retrofitting all the walls of a house to dynamic walls.

b. If we include the effect of heat losses through the foundation, assuming U-effective of U_eff = 0.07 Btu/ft²·hr·°F and an area of 2,000 ft² for the foundation, do your estimations change significantly.

c. Determine the impact of dynamic walls if the infiltration/ventilation rate is reduced to 0.35 ACH.

Assume that the heating system is a gas furnace with an efficiency of 0.80 and that the fuel cost is $14.0/MMBtu.