Environmental impact and energy performance of groundwater heat pumps in urban retrofit

• Published in: Energy and buildings Vol. 261; p. 111964
• Main Authors: Schibuola, Luigi, Tambani, Chiara
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.04.2022; Elsevier BV
• Subjects: 5GDHC network; Air conditioning; Air temperature; Boilers; Carbon dioxide; Carbon dioxide emissions; City resilience; Condensers; Condensers (liquefiers); Cooling; Cooling systems; Decarbonisation actions; Emissions control; Energy conservation; Environmental impact; Groundwater; Groundwater heat pump; Heat exchangers; Heat pumps; Heating; Hybrid systems; Mitigation; Retrofitting; Urban areas; Urban heat island; Urban heat islands; Urban weather model; 5GDHC; ASHP; DH; UWG; Groundwater heat pump; 5GDHC network; HP; Urban heat island; HVAC; Urban weather model; Decarbonisation actions; UHI; GWHP; City resilience
• ISSN: 0378-7788; 1872-6178
• DOI: 10.1016/j.enbuild.2022.111964

•The mutual interaction between UHI effect and HVAC systems was investigated.•A 5th generation district heating and cooling network fed by groundwater is studied.•The modeling provides the annual performances of an urban area and its network.•A comparison vs air source heat pump in terms of environmental benefits is reported.•Outcomes show UHI mitigation relevance in addition to decarbonisation contribution. Increasing efforts are addressed to improve heating, ventilation and air conditioning systems to achieve the decarbonization goal also in the building sector. But less attention is actually devoted to their impact on the urban heat island (UHI) phenomenon. Starting from the UHI assessment and its impact on building heating and cooling demand, a performance comparison is presented between groundwater heat pumps (GWHP) supplied by a district network and air source heat pumps (ASHP_1). Hybrid systems with small ASHPs and condensing boilers (ASHP_2) are also considered. An urban area, network and heat pumps were modeled for this study. In summer, the removal from the urban area of the heat dissipated by condensers thanks to GWHPs reduces the average UHI intensity with ASHPs by 45% and the relative cooling demand increment by 42.6%. A more favorable temperature of the groundwater than outside air permits a net superiority of the GWHP efficiency. At annual level, the GWHP provides energy savings of 27% and 34.5% and CO2 emission reductions of 27% and 39.5% compared to ASHP_1 and ASHP_2 respectively. The UHI mitigation to improve comfort and resilience in urban areas is an important added value for the contribution to decarbonization that a GWHP network can provide.