Discrete fourier series models for building auxiliary energy loads based on network formulation techniques

Abstract

This paper presents a discrete Fourier series methodology for determining auxiliary energy loads in buildings. By applying network theory, flexible and efficient computer formulation techniques for the nodal frequency domain equations are developed. Two types of auxiliary sources are modelled; in the first one the room air temperature profile is specified, while in the second one an auxiliary heating/cooling source is modelled as a proportional control heat source. Unlike analytical frequency domain approaches such as those based on the Fourier transform, the discrete frequency domain methodology employed allows complex heat transfer mechanisms such as longwave radiant exchanges between room surfaces to be directly included in the formulation, and time-varying conductances such as that for a window with night insulation are also modelled. Thus, the methodology is particularly suitable for passive solar analysis.