Consider a house in Blacksburg, Virginia. The typical annual space-heating load for this size of a house is 10010^6 Btu. That is, with no insulation in the attic, we lose about 10010^6 Btu per year. With insulation in the attic the amount of heat lost each year will be reduced. The value of energy savings that results from adding insulation and reducing heat loss is dependent on what type of residential heating furnace is installed. Assume that an electrical resistance furnace is installed by thebuilder, and its efficiency is near 100%. The cost of electricity is $0.16 per kWh. The cost of several insulation alternatives and associated space-heating loads for this house are given in the following table. Which amount of attic insulation is most economical? The life of the insulation is estimated to be 24 years.

Consider a house in Blacksburg, Virginia. The typical annual space heating load for this size of a house is 100 106 Btu. That is, with no insulation in the attic, we lose about 100 106 Btu per year. With insulation in the attic the amount of heat lost each year will be reduced. The value of energy savings that results from adding insulation and reducing heat loss is dependent on what type of residential heating furnace is installed. Assume that an electrical resistance furnace is installed by the builder, and its efficiency is near 100%. The cost of electricity is $0.16 per kWh. The cost of several insulation alternatives and associated space-heating loads for this house are given in the following table. Which amount of attic insulation is most economical? The life of the insulation is estimated to be 24 years R11 2,200 74.1 x 10 Amount of Insulation R19 3,700 R30 5,000 67.4 x 10 R38 6,200 66.2 x 106 Investment cost ($) Annual heating load (Btulyear) 69.8 x 106 Recall that 1 Btu 0.293 Wh and calculate the cost of electricity per million Btu Fill in the table below. (Round to the nearest cent.) R11 R19 R30 R38 3700 5000 6200 Investment cost ($) Cost of heat loss per year ($) Cost of heat loss over 24 years (S) Total life cycle costs ($) 2200 To minimize total life-cycle costs, seleinsulation