Getting to net zero: Islington’s social housing stock

Abstract

This paper describes the development of a detailed plan to get the social housing stock of the Borough of Islington in London, UK, to net zero carbon emissions. This stock is very diverse in form, age and construction, and includes houses, flats and maisonettes. A total of 4500 buildings containing some 33,300 dwellings were modelled using the 3DStock method. Six packages of measures combining fabric improvements, heat pumps and photovoltaic installations were evaluated for each dwelling individually, in terms of costs, the impacts on gas and electricity use, and predicted cuts in carbon emissions. The rollout of measures between 2020 and 2030 was modelled with a specially developed scenario tool, allowing the user to set different criteria and priorities. Fabric measures on their own were shown to achieve only a 13% cut in gas use on average. Heat pumps are the key to displacing gas use. With all measures combined and taking account of the predicted decarbonisation of the electricity supply, it is only possible to achieve an overall 70% cut in emissions by 2030. Policy relevance The development of a detailed practical plan of action is described: an applied case study with the close engagement of the local authority—not a theoretical desk exercise. Each dwelling in Islington’s housing stock was examined and measured separately. The modelling did not rely on ‘archetypes’ as in many such studies. Realistic retrofit options were analysed in each case, using current cost data from practitioners. The same approach could be applied directly to other London boroughs, and for local authorities outside the capital, although different costs and other local factors would apply. For readers outside the UK, the methodology and tools could serve as exemplars. The findings about the respective contributions of heat pumps, solar photovoltaics and fabric measures, and the effects of different priorities in the rollout of retrofits, have relevance for policymaking more generally at local and national levels.