Development and evaluation of a control strategy for water-based radiant systems with integrated phase change materials

Experimental and numerical studies have demonstrated the great energy savings potential and CO2 emission reduction that can be achieved with thermally activated building systems (TABS). However, one downside of TABS is that the system has to be incorporated in the building from the design stage, which limits its application to new buildings. To encourage the application of high thermal mass radiant systems in refurbishment, the authors developed a radiant ceiling panel with incorporated phase change material (RCP-PCM). The focus of this study is on the control strategy to operate the system. Whole-building energy simulations have been used for evaluating the performance of the RCP-PCM system operating under the proposed control strategy. Results indicate that the control strategy can be regarded as effective since it can respond well to changes in cooling and heating demand, meet the thermal comfort requirements, is simple to implement, and can lead to an energy-efficient operation due to the capability to operate only at night-time. Results also show that for cooling-dominated climates, a phase change material (PCM) with a melting temperature of 21℃ is desirable to increase the passive cooling power of the system. However, in climates where both cooling and heating are required, a PCM with a melting temperature of 24℃ results in better thermal performance. The RCP-PCM system was able to maintain the indoor temperature within the specified range of thermal comfort for more than 96% of the total occupied hours in cooling-dominated climates and climates with both cooling and heating requirements.