A cold storage building has 200-mm thick concrete walls. The interior walls are insulated with 25-mm thick extruded polystyrene board covered with 12-mm thick plywood. k. = 1.95 W/m K for the concrete, kepB = 0.030 W/m K for the polystyrene board, and kp = 0.12 W/m · K for the plywood. The inner wall is exposed to cold air at T = -5°C with convection coefficient h, = 8 W/m2 K. The outer wall is exposed to hot40°C with convection coefficient h = 35 W/m2 K.air at a) Find the overall heat transfer coefficient for this wall (answer: 0.8407 W/m² K). b) Find the heat flux through the wall (answer: 37.8 W/m2 ).

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