The wall of a bakery oven is built of insulating brick 10 cm thick and thermal conductivity 0.22 J m-1 s-1 °C-1.
Steel reinforcing members penetrate the brick, and their total area of cross-section represents 1% of the
inside wall area of the oven.
If the thermal conductivity of the steel is 45 J m-1 s-1 °C-1 calculate (a) the relative proportions of the total heat
transferred through the wall by the brick and by the steel and (b) the heat loss for each m2 of oven wall if the
inner side of the wall is at 230°C and the outer side is at 25°C.