Environmental compatibility and economic feasibility of ground source heat pumps in tropical Asia regarding lifecycle aspects: A case study in Bangkok, Thailand

Ground source heat pumps (GSHPs) in tropical regions require a large-scale ground heat exchanger (GHE) owing to the excessive cooling load and high subsurface temperatures, resulting in increased initial costs and greenhouse gas (GHG) emissions in all phases, excluding the operation phase. However, investigations of the compatibility of GSHPs in tropical regions have been limited to evaluations based on energy consumption in the operation phase, leading to a lack of clarity regarding the contribution of increased initial cost and GHG emissions to the environmental compatibility and economic feasibility based on lifecycle aspects. Thus, this study aimed to evaluate the GHG emissions over the entire life cycle and the cost payback time of a 20 -kW capacity GSHP in Bangkok, Thailand, designed with a predicted 50-year heat sink temperature. The results confirmed that the required scale of GHEs is twice as large in tropical regions as in mid-high latitude regions; nevertheless, the energy-saving of the GSHP resulted in an 8.8 % reduction in GHG emissions over the entire life cycle compared to an air source heat pump. However, the capital investment cannot be recovered within the lifetime of the GSHP, requiring incentives and cost reduction due to the growth of the GSHP market.