Finite difference method heat transfer applied to thermally activated building systems

Abstract

Energy efficient Heating Ventilation Air Conditioning (HVAC) systems are required to off-set the rising cost of electricity and to reduce the amount of natural resources consumed. The implementation of alternative energy saving technologies is often not realized due to various factors hampering the implementation thereof. Thermally Activated Building Systems (TABS) is one of such technologies that utilize the inherent heat storage capacity of a building's concrete structure for comfort heating and cooling purposes. The concrete's heat storage capacity and various other factors need to be accounted for in order to dynamically predict the heat transfer behaviour of such systems. In this study, a commercial software program (MS Excel) was used to develop a two-dimensional FDM heat transfer model capable of dynamically predicting the air and surface temperatures of an enclosure. An experimental model was constructed and used to experimentally validated temperature predictions obtained from the FDM model. The average prediction accuracy of the heat transfer model ranged between -0.4°C and +1.4°C for the enclosure's surface temperatures and varied by +0.7°C for the enclosure's air temperature.