A glass window 0.45cm thick measures 90cm by 35cm . If the inside and outside temperatures differ by 18?, the heat flows through this window per minute is 64kJ.
(a) To compare the relative efficiency of air and glass as insulators, calculate the heat flows through this window per minute with a 0.45cm thick layer of air instead of glass.
(kJ/min)
(b) By what factor is the rate of heat transfer reduced?