A room measures 3 x 4 m with a height of 3 m. The floor of the room is heated to 300 K, the ceiling is kept at 290 K, and side walls are assumed perfectly insulated at the outside. The emissivity of all surfaces is 0.8. Heat convection in the room can be neglected.

i) Draw the network representation of heat transfer

ii) Find the net radiation interchange between the floor and ceiling

iii) Find the temperature of the side walls