Room thermal modelling adapted to the test of HVAC control systems

This paper presents the development of a room model adapted to the study of the influence of the sensor position in building thermal control. The temperature measured by the sensor of a room temperature controller depends on its position in the zone. The more the room conditions are non-homogeneous, the more the temperature at the sensor position can differ from the “mean air temperature”. Models, currently used for control studies, are very simplified. They consider the room air as perfectly mixed. Other models, actually used for comfort studies, are on the one hand not adapted to the use for control studies, where dynamic models are necessary. On the other hand, they are not generic enough to provide a flexible and usable testing tool for room controllers. The important phenomena, to be represented in the model, are analysed experimentally and by detailed simulation. From this analysis, a detailed list of criteria for the development of zone models is obtained. The criteria are used to develop a new room model. The proposed model is able to distinguish between centre air and different sensor air temperatures with time variation. An application for a zone conditioned by a fan coil unit illustrates the model. Validations of the model are carried out in a real test room.