The computation of heat flows through multi-layer slabs

Abstract To model the transient thermal behaviour of buildings it is necessary to calculate time-dependent heat flows through multi-layer slabs representing walls, floors and roofs. A numerical method is presented which calculates these from a knowledge of past temperatures on each side of the slab at specified time intervals. Response factors are found using Laplace transforms. The number of response factors is minimized using previously calculated heat fluxes. An estimate of the error introduced by taking only a finite number of response factors is given and a correction term derived. The method is compared with the more standard z-transform method.