A vertical, double-pane window, which is I m on a side and has a 25-mm gap filled with atmospheric air, separates quiescent room air at T_∞,o = 20°C from quiescent ambient air at T_∞,o = - 20°C. Radiation exchange between the window panes, as well as between each pane and its surroundings, may be neglected.

(a) Neglecting the thermal resistance associated with conduction heat transfer across each pane, determine the corresponding temperature of each pane and the rate of heat transfer through the window.

(b) Comment on the validity of neglecting the conduction resistance of the panes if each is of thickness Lp = 6mm.

Air Ambient air Room air L. Ta Glas