Integrating Ground Source Heat Pumps into Elderly Homes as Energy-efficient Heating and Cooling Solution - A Swedish Case Study

Sammanfattning: Energy efficiency and environmental questions have gained increased attention over the last decade. In combination with global warming and increasing cooling demands, the Swedish market for combined heating and cooling solutions such as ground source heat pumps expands. As it currently stands, the multi-family building market is highly dominated by district heating, while the market share of combined heating and cooling solutions is insignificant. Several factors are contributing to this market situation such as the widespread of district heating networks, the high installation cost of the borehole heat exchanger, and the site conditions. This study aims to evaluate the integration of ground source heat pumps into Swedish elderly homes. The study is divided into the following four parts: (1) analysis of energy performance and thermal comfort conditions using a case study, (2) evaluation of the implementation of passive and active cooling measures to improve the indoor thermal comfort, (3) analysis of the ground source heat pumps combined heating and cooling contribution to reduced heating demand and achieving adequate indoor climate, (4) comparison of the ground source heat pump against alternative heating and cooling systems from a life-cycle costing perspective. The results indicate that the integration of GSHPs in elderly homes significantly decreases the heating energy and highly contribute to the fulfilment of Swedish energy goals. The outlet fluid temperature of the boreholes were insufficient to provide the desired AHU cooling coil inlet temperature and additional room cooling units were required. The utilisation of free cooling was possible and reduced the cooling energy by 26 % and the capacity of the chiller by 29 % in comparison to utilising an external chiller only. Replacing boilers operating on electricity and oil with GSHPs was highly profitable while the replacement of less expensive heating sources such as district heating and boilers operating on pellets was highly dependent on electricity and pellets price. The economical outcome of the analysed cooling systems is dependent on whether the GSHP is used for combined heating and cooling solutions or for cooling only.