(a) What is the rate of heat flow through the door, assuming that the surface temperatures are those of the surrounding air?

 

 

A carpenter builds a solid wood door with dimensions 2.5m x 0.8m x 8 cm. Its thermal conductivity is kdoor = 0.02 Wm-K-. The inside temperature is T = 300.15 K, and the outside temperature is T = 253.15 K. (b) By what factor is the heat flow increased if a window 0.7 m is inserted, assuming the glass is 0.5 cm thick and the surface temperatures are again those of the surrounding air. The thermal conductivity of glass is kwindow = 1.08 Wm-K-.