CALCULATION OF THE STEADY-STATE HEAT-TRANSFER THROUGH A SLAB-ON-GROUND FLOOR

An analytic formula is derived for the steady-state heat transfer through a slab-on-ground floor, with and without thermal insulation, based on the solution of the fundamental heat transfer equation with relevant boundary conditions. So far as the building dimensions are concerned, the heat loss depends only on a "characteristic length" of the floor, defined as the floor area divided by half the exposed perimeter, a result which greatly simplifies the expression of heat losses and their evaluation for a building of arbitrary shape. The heat transfer is restricted by the thickness of the external walls, surface resistance and by any applied thermal insulation. The influence of these factors is combined appropriately so as to permit the straightforward evaluation of the thermal transmittance of the floor for any wall thickness and insulation thickness.