Effects of the room temperature sensor position and radiator sizing on indoor thermal comfort and energy performances

In this paper, a simplified zonal model for the evaluation of the spatial distribution of the air temperature in a thermal zone is presented. This model, in which the air flow is caused only by buoyancy forces, is implemented in ALMABuild. The model is used for the analysis of the effect of the temperature sensor positioning on the control system behaviour and on the indoor comfort conditions. This analysis is performed considering a multi-zone building composed by three offices, focusing the evaluation to the central one. The office is heated by means of a radiator in which the hot water flow rate is varied by a valve controlled via a room temperature sensor. By means of numerical simulations, indoor comfort conditions, energy consumptions and control system response are evaluated for three different sensor positions (far from the radiator, in the middle of the office, close to the radiator), two radiator sizes (one obtained by imposing a high supply water temperature, 80 °C, the other a low supply temperature, 60 °C) and two control strategies (weather compensation and fast restart). The results presented in this study and demonstrate how complete dynamic energy simulation tools can provide to the designer important information, like the room temperature sensor position that should be close to the emitter and far from cold external walls, for the optimal design of HVAC systems.