1. The problem statement, all variables and given/known data The cross section of a wall is shown in the figure below. To reduce the heat flow, an air gap (still air) of 6cm is created between the brick wall layers of 14cm thick, each. The thermal conductivities of the brick wall and the still air are: Kair = 0.032 W/m.K and Kbrick = 0.9 W/m.K, respectively. Calculate thermal resistance. This is only part of the question as I have no problem with the rest. The convective heat transfer coefficient has not been given thus making it very difficult for me to even begin. 2. Relevant equations R=1/hA R=L/kA Q=T1-T2/Rtotal 3. The attempt at a solution As no convective heat transfer coefficient has been given, I can't even begin to calculate the thermal resistance. It's probably something very simple but I just can't get my head around it.