2-13 A certain building wall consists of 6.0 in of concrete [k =1.2 W/m °C], 2.0 in of fiberglass insulation, and in of gypsum board [k=0.05 W/m- °C]. The inside and outside convection coefficients...

Extracted text: 2-13 A certain building wall consists of 6.0 in of concrete [k =1.2 W/m °C], 2.0 in of fiberglass insulation, and in of gypsum board [k=0.05 W/m- °C]. The inside and outside convection coefficients are 2.0 and 7.0 Btu/h ft2 . °F, respectively. The outside air temperature is 20°F, and the inside temperature is 72°F. Calculate the overall heat-transfer coefficient for the wall, the R value, and the heat loss per unit area.