$2-28.$ According to the U$.$S$.$ Department of the Interior, the amount of energy lost because of poorly insulated homes is equivalent to $2$ million barrels of oil per day. In $2009,$ this is more oil than the United States imports from Saudi Arabia each day. If we were to insulate our homes as determined by Example $2-7,$ we could eliminate our oil dependence on Saudi Arabia. If the cost of electricity increases to $$0\mathrm{.}15$ per $kWh$ and the cost of insulation quadruples, how much insulation should be chosen in Example $2-7?(2\mathrm{.}3)$

$72$

Chapter $2/$ Cost Concepts And Design Economics

In view of these data, which amount of attic insulation is most economical? The life of the insulation is estimated to be $25$ years.

Solution

Set up a table to examine total life$-$cycle costs:

$\backslash$table$[[,R11,$R$19,$R$30,R38$