A glass window of width W=lm and height H=2m is 5mm thick and has a thermal conductivity= 1.4 w/mK. If the inner and outer surface temperatures of the glass are 15°C and –20°C of respectively , on a cold winter day, what is the rate of heat loss through the glass? To reduce heat loss through the windows, it is customary to use a double panes construction in which adjoining panes are separated by an air space. If the spacing is 10mm and the glass surface in contact with the air have temperature of 10°C and –15°C, what is the rate of heat loss from a 1m×2m window?The thermal conductivity of air is ka= 0.024 w/mK.

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