Proposal for a highly intermittent heating law for discontinuously occupied buildings

Abstract

This article presents an intermittent heating controller which is designed for calculating the supply temperature of hot-water-radiator heating systems. This controller uses a new heating law which has been obtained by inverting a simplified model for calculating the internal temperature of a building in relation to the external temperature, as well as the supply temperature of the distribution circuit and the temperature of the structure. The latter is used to determine the thermal state of the building, which is an important parameter in the evaluation of energy needs when a building is heated in an intermittent mode. During non-occupancy periods, the parameters of the model are automatically modified by a recursive least-squares routine. A second law optimizes the heating restart time during non-occupancy periods; this law also incorporates a learning mechanism. The controller's performance is analysed, and the results are compared with those of a controller using a classical heating law which does not take into account the thermal state of building. Numerical simulations demonstrate that the new heating controller leads to performances comparable with those obtained by classical methods, but for a higher degree of intermittence. This means that the comfort obtained is similar, but that the energy consumption is lower. The new heating law also proves to be advantageous in other ways; it provides faster learning, much better lower temperature control and a reduction in instances of overheating during inter-season periods, when little heating is needed.