It is proposed to build a cold room having an outer wall of maple wood(100mm thick) and an inner wall of glass(10mm thick), with the space in between(100mm) filled with insulating fiber. The inner wall temperautre is 20 celcius and the outer wall is maintained at the air temperature of 30 celcius. Calculate the rate of heat penetrated through a wall surface of 1m^2. And calculate the temperature difference across the interfaces of the three layers.