A building has to be maintained at 21°C (dry bulb) and 14.5°C (wet bulb). The dew point temperature under these conditions is 10.17°C. The outside temperature is -23°C (dry bulb) and the internal and external surface heat transfer coefficients are 8 and 23 W/m2K respectively. If the building wall has a thermal conductivity of 1.2 W/mK, the minimum thickness (in m) of the wall required to prevent condensation is

A building has to be maintained at 21°C (dry bulb) and 14.5°C (wet b

1.	A building has to be maintained at 21°C (dry bulb) and 14.5°C (wet bulb). The dew point temperature under these conditions is 10.17°C. The outside temperature is -23°C (dry bulb) and the internal and external surface heat transfer coefficients are 8 and 23 W/m2K respectively. If the building wall has a thermal conductivity of 1.2 W/mK, the minimum thickness (in m) of the wall required to prevent condensation is
A.	0.471
B.	0.407
C.	0.321
D.	0.125
Answer» C. 0.321

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