Heat pump system | Phase change materials Heat pumpS: the next phase? An InnovateUK research project is looking to combine phase change materials with a smart heat pump system to cut energy use, reduce overheating and control humidity in homes. PCM Products Sam Gledhill explains how the system works A group of companies is testing a heat pump system combined with solar panels and phase change materials to offer occupants energy efficient heating and cooling. Currently, only 0.5% of UK homes have air conditioning, but, for those that do, cooling represents around 30% of total energy consumption. The new system, funded by InnovateUK, is known as Total Heat Energy and Moist Air Control (Themac) and aims to reduce significantly the energy required for cooling, Simulated cooling load in a typical office Cooling load (kWh) 1,000 800 600 400 200 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 1: The red bars show the cooling demand for a typical office; the blue bars show the demand in the same office for cooling if the PCM passive cooling is installed if required. Its goal is to maintain temperature and humidity within a building throughout diurnal, seasonal and occupancy changes while supplying hot water and heating from a renewable source. The consortium consists of specialists in their respective fields: PCM Products, involved with phase change materials (PCMs); heat pump manufacturer Arkaya Energy; renewable housing developer Positive Homes; and a research institute in the University ofNottingham. Its tri-modular approach aims to achieve a complete comfort solution. A high-performance heat pump supplies sufficient heating in winter and can provide domestic hot water. A super-water-absorbent, polymer-based desiccant is able to humidify or dehumidify the air, thereby maintaining relative humidity at a comfortable level. Finally, a passive PCM system helps prevent overheating during summer days while maintaining a habitable temperature overnight. The Arkaya Energy heat pump is combined with solar thermal panels that can be mounted on roofs or walls. They draw thermal energy from the environment, even in the absence of direct solar irradiance. This gives the overall system a higher coefficient of performance (COP) than traditional systems, and it can reach temperatures of up to 68C all year round with little decrease in efficiency. The heat pump has two cycles a water cycle and a refrigerant cycle with a heat exchanger in between and a sensor monitors these to minimise heat loss. The system works at a higher pressure than most heat pumps, which improves COP and reduces heat losses in winter and overnight. The high temperatures allow the heat pump to supply energy directly to traditional radiators. The technology is contained within a smart box, which can be put in lofts, cupboards or even outdoors. This, combined with minimal servicing requirements, offers consumers a user-friendly solution. 40 January 2019 www.cibsejournal.com CIBSE Jan19 pp40-41 Thermac heat pump PCM.indd 40 21/12/2018 15:08