An outside wall of a building is constructed of 1/2 inch gypsum sheeting, 8 inches of concrete block (hollow, 3 oval core), and 4 inches of common brick. The inside of the building is maintained at 75F dry-bulb temperature and 65F wet-bulb temperature. Barometric pressure is 14.696 psia. Outside conditions are -30F dry bulb temperature and 80% relative humidity. Outside wind velocity is 15 mph.
a) Calculate the heat transmission through the wall and the temperatures at each surface and interface.
b) Assume vapor flow continuity and calculate the vapor flow rate through the wall and the vapor pressure at each surface and interface.
c) Will condensation occur based on your results?
d) How many layers of 1/2 inch insulation board (k=0.36 Btu/hrft^3F/in) must be added to the wall to prevent condensation on the inside surface