Thermal and comfort control for Radiant Heating/Cooling Systems

Water based, surface embedded heating and cooling systems, also referred to as radiant heating cooling systems (RHCS), are growing in popularity, due to their advantages in terms of low-noise, uniform temperature distribution, and energy saving potential. However, it is in general recognized that traditional control systems may deteriorate the energy performance of radiant systems, so that it is important to devise ad hoc strategies for such kind of systems. In this paper, a model-based approach is used to design an efficient control architecture for radiant heating/cooling systems coupled with fan-coil units with the main objective of increasing both thermal comfort for building occupants and energy saving. A building lumped parameter model for hygrothermal analysis coupled with a 2D discretization scheme for radiant heating/cooling systems is development in the Matlab/Simulink environment. The model simulation tool, together with a simple load forecasting strategy, allows to design a suitable controller, that we name comfortstat, which is based on the regulation of the Predicted Mean Vote (PMV) thermal comfort index. In this way, thermoigrometric conditions are kept within a range of acceptable comfort values, under performance constraints for reducing energy consumption and preventing floor surface condensation. The results show that the proposed thermal comfort control algorithm gives better satisfaction for the occupants and superior performance with respect to standard approaches.