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

Abstract

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.

Popular Abstract

The awareness of environmental questions and energy-efficiency has increased over the past decades as climate change and global warming are becoming more apparent. This has contributed to the establishment of several environmental goals promoting renewable energies and increased energy efficiencies. To reach these goals, improvements are required within high energy use sectors. One of these high energy use sectors is the building sector in which more than half of the energy use is utilised for heating purposes in Sweden. With the possibility of reducing the heating energy use in combination with the increased cooling demands caused by global warming, energy-efficient combined heating and cooling solutions are sought after. This opens the market for ground source heat pumps, which are utilising the ground as a renewable energy source. Ground source heat pump systems are capable of providing 3 to 5 units of heating energy for each unit supplied to the system and can provide free cooling by directly circulating the heat carrier fluid through the ground.
The purpose of this study is to analyse the integration of ground source heat pumps to provide heating and cooling to an elderly home located in southern Sweden. The energy performance and thermal comfort of the elderly home were analysed using energy simulations. To improve the indoor climate of the elderly home three measures were applied: the windows were equipped with external shading devices, the air handling unit was equipped with a cooling coil and additional room cooling units were installed and adapted to the special requirements in elderly homes. Two ground source heat pump systems were introduced and the energy performance, life-cycle costings and the free cooling potential of the systems were analysed. For the energy performance, the ground source heat pump systems were compared to a base case boiler operating on pellets. To analyse the life-cycle costings, the savings generated from replacing alternative heating systems with ground source heat pumps were calculated. To compare the life-cycle costings for cooling purposes the net present value was calculated. The free cooling potential of the ground source heat pump system was analysed by connecting the air handling unit cooling coil and room cooling units to the boreholes and simulating the fluid temperatures.
From the energy simulations, it was found that the integration of external shading devices adapted to the care recipients mental health was ineffective and that the most efficient cooling measure was the integration of room cooling units. The primary energy use of the proposed ground source heat pump systems was reduced by 8 % in comparison to the base case. The savings generated by replacing expensive heating sources such as oil and electricity yielded large savings and the pay-back time of the ground source heat pump system was only a few years. When replacing less expensive heating systems the sizing factor and electricity price were the key-parameters. The results from the cooling life-cycle costings were dependent on if the ground source heat pump system was utilised for combined heating and cooling or cooling only. The utilisation of free cooling for the room cooling units was successful. To further increase the free cooling potential the cooling coil in the air handling unit should be dimensioned for high inlet temperatures. The use of ground source heat pumps can contribute to the fulfilment of the Swedish energy goals and by the combination of district heating and large-scale heat pumps, the utilisation of ground source heat pumps in urban areas is possible.

• author: Kuhleber, Moritz
• supervisor: Marwan Y A Abugabbara
• organization: Division of Energy and Building Design; Department of Architecture and Built Environment
• course: AEBM01 20211
• year: 2021
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Ground source heat pumps, Elderly homes, Thermal comfort, Energy performance, Multi-family buildings
• language: English
• id: 9061770
• date added to LUP: 2021-07-26 10:00:39
• date last changed: 2021-07-26 10:00:39