Calculating thermal resistance and U value

The thermal conductivity of a material and its thermal resistance are related by the equation:


For example consider a 0.22 m thick brick wall with a thermal conductivity of 0.6 Wm^-1oC^{- 1}.
Thermal resistance = 0.22/0.6 = 0.367 m^2oCW^-1.

The U value of a barrier is defined as:


So for the brick wall the U value would be 1/0.367 = 2.72 Wm^-2oC^-1. If the wall had a lower thermal conductivity its thermal resistance would have been greater