Retrofitting a gas-powered residential development with a communal heat pump system: a case study in the UK using an MCDM-based approach

This study evaluates the viability of retrofitting a high-rise residential building in Newham, London, to replace natural gas heating with heat pump technology in line with the UK government's 2035 target for decarbonisation. The paper uses Multi-Criteria Decision-Making (MCDM) methodologies to assess seven retrofit scenarios involving various improvements to the building's fabric and heating system, aiming to reduce energy consumption and CO ₂ emissions. The study considers factors such as capital cost, energy efficiency, running costs, and environmental impact. This paper assumed the number one priority of the building owner to be the capital cost of the project, as Scenario 2 was intended to be used as a comparative benchmark for the other Scenarios and thus had no modifications, the capital cost would be zero, therefore skewing the data to produce a very high ranking despite only being the benchmark. The results indicate that Scenario 7, which included an EnerPHit building fabric with an Air Source Heat Pump (ASHP) and ancillary technologies, performed the best. This scenario resulted in a total electricity saving of 98,221 kWh and achieved a significant reduction in CO ₂ emissions (0.15 tonnes per year). It also attained a Standard Assessment Procedures (SAP) rating of 84B and demonstrated an Air Source Heat Pump Coefficient of Performance (ASHP CoP) and Seasonal Coefficient of Performance (SCoP) of 2.698 and 3.16 respectively. Despite its high initial capital cost of £646,118, Scenario 7 offered a relatively low annual running cost of £4341. This represents an annual saving of approximately £24,280, resulting in a payback period of around 13.6 years compared to Scenario 2. The findings emphasize the need to carefully balance upfront investment with long-term operational savings and environmental benefits.