Refer to Example 2-7. If the average inside temperature of this house in Virginia is increased from 65° F to 72° F, what is the most economical insulation amount? Assume that 100,000,000 Btu are lost with no insulation when the thermostat is set at 65°F. The cost of electricity is now $0,086 per kWh. In addition, the cost of insulation has increased by 50%. Develop a spreadsheet to solve this problem.