A garage has 90-mm thick common brick walls. The owner wants to insulate the interior walls with glass-fiber insulation batts and 10-mm thick gypsum board. The air inside the garage

is at 10°C with a convection coefficient of 8 W/m2 K. The air outside is at -15°C with a convection coefficient is 35 W/m2 - K. The surface area of the brick walls is 50 m². Use thermal resistance to solve both parts of this problem. a) Find the heat loss through the walls if they are not insulated and there is no gypsum board (answer: 4648 W). b) Find the thickness of the glass-fiber insulation batts needed to reduce the heat loss to 600 W after the walls are insulated (answer: 66 mm).