A double-pane insulated window unit consists of two 1-cm-thick pieces of glass separated by a 1.8 cm layer of air. The unit measures 4 m in width and is 3 m wide. Under conditions where the extreme outside temperature of the glass is at -10°C and air, at 27°C, is adjacent to the inside glass surface, with h_i = 12 W/m² · K, determine
a. The inside glass surface temperature
b. The rate of heat transfer through the window unit.
The air gap between glass panes may be treated as a purely conductive layer with k = 0.0262 W/m · K. Thermal radiation is to be neglected.