Towards low carbon homes – A simulation analysis of building-integrated air-source heat pump systems

A comparative transient simulation analysis for domestic buildings with a floor-embedded heating system coupled to a modern air source heat-pump (ASHP) has been carried out using the TRNSYS numerical modeling environment for various UK locations. The effects of heat-pump control during off-peak electricity tariff periods in conjunction with varying building fabric characteristics were analysed and the results show that for the locations investigated, running costs and CO2 emissions were lower for the ASHP platform than for a comparative gas boiler heating system. It was also found that by utilizing the thermal mass of a concrete floor slab or by integrating external insulation, acceptable comfort levels during the heating season were maintained when operating the ASHP solely during off-peak tariff periods. A thinner concrete floor slab containing phase change material (PCM) provided a slightly improved comfort level during winter and also reduced overheating during summer in buildings with a high level of insulation. Finally, when utilising a floor-embedded PCM material, it was found that the thermal properties of the PCM material must be carefully matched with case-specific building fabric thermal performance parameters in order to ensure effective internal environmental control.

► An in-depth study of the feasibility of using a range of off-peak electricity tariffs for domestic ASHP operation has been carried out for the first time.
► An intercomparison of ASHP operation for a range of building fabric configurations has been performed, providing a very useful design resource for building designers.
► The use of tailored floor-embedded PCM materials within this context has been explored for the first time.
► The impact evaluation of solid concrete floor slab configuration on internal comfort provides a valuable practical guide for designers.