1. The problem statement, all variables and given/known data The brick wall of a building has dimensions of 4m by 10m, it is 15cm thick with a coefficient of thermal conductivity of 0.8 (Wm^-1C^-1). (a) How much heat flows through the wall in a 12-hour period when the average inside temperature is 20 C and the average outside temperature is 5 C? (b) Will a 2kW heater operating in the room compensate for this? (c) A layer of insulating material, thickness 5cm, k = 0.04 (Wm^-1C^-1) is added to the inside of the wall. Calculate the rate of heat loss after the addition of this layer. 2. Relevant equations The Law of Heat Conduction: H = (dQ/dt) = - k A (dT/dx) Another equation I found is the following, but I'm not sure if it's relevant here: H = A(T2 – T1)/(summation Ri), where the summation is taken from i = 1 to i = n, and Ri = (Li/ki). 3. The attempt at a solution I've attemped (a) using the Law of Heat Conduction, but I think my answer seems very wrong! I said the area A = 4m x 10m = 40m^2 k = 0.8 dx = 15cm = 0.15m. Using equation above: (dQ/dt) = - (0.8) (40) (15/0.15) (dQ/dt) = -3200 12 hours is 720 mins or 43200 seconds. dQ = -3200 (43200) dQ = - 138240000 W, or 138240 kW. Fairly sure it's wrong, and even if it was right, I'm not sure how to do part (b). Do I just compare my answer to (a) with the 2kw given in (b)? And c is beyond me at the moment, sadly! :( Any help would be greatly appreciated, thanks.