Islington Council and UCL deliver housing retrofit in drive to Net Zero

The London Borough of Islington has collaborated with the UCL Energy Institute to devise a detailed strategy to decarbonise 33,000 social houses.

Islington’s housing stock is incredibly diverse and contains everything from 18th century houses in conservation areas, through to 1970s high-rise blocks and new builds.

As a first step towards achieving their strategy to become carbon net zero by 2030, the Council’s leadership sought out external expertise to get a clearer understanding of the housing stock and what might be feasible and appropriate in terms of retrofit.

One academic group that has gained a reputation for innovative research in this area is the Building Stock Lab – part of the UCL Energy Institute, based at Bartlett School of Environment, Energy and Resources.

Their key innovation is 3DStock, a method for modelling all buildings – domestic, non-domestic and mixed-use – in a locality, in three dimensions and located geographically. The primary purpose is the analysis of energy performance, but there are many other potential applications. It draws on data from a range of sources, including Environment Agency aircraft equipped with LiDAR equipment.

The UCL team were ultimately successful in bidding for the project to analyse the social housing stock in Islington – with UCL Consultants providing support for the application, budgeting and contracting.

Costing various scenarios

Led by Senior Research Fellow Steve Evans and Professor Paul Ruyssevelt (Chair of Energy & Building Performance), and working in collaboration with colleagues from UCL Civil, Environmental and Geomatic Engineering, the team used 3DStock to model every single one of Islington’s 33,000 social housing residences. This allowed the UCL team to predict the costs and results of retrofitting each individual home.

Various projected scenarios were calculated with a 2030 end date, in recognition of Islington’s stated net zero ambitions. These ranged incrementally, from a ‘do nothing’ response through to an ‘all measures’ package.

The most ambitious package, combining air-source and ground-source heat pumps, double glazing, insulation and solar PV where viable, was found to potentially bring a 70% reduction in emissions by 2030, at an estimated cost of £1.6bn. Much of the remaining 30% of emissions was found to be outside Islington Council’s control, being largely attributable to fossil fuel usage by the National Grid. Interestingly though, the increasing use of renewables in the national energy mix meant that even the ‘do nothing’ package also saw measurable emissions reductions.

Putting plans into action

Based on the evidence that came out of the project – which was facilitated by UCLC – Islington Council then secured significant funding to start retrofitting the first batch of homes in the Borough.

This overall initiative forms a key part of the Borough’s ‘Vision 2030,’ strategy to become carbon net zero by 2030.

“We can’t just make newer, better buildings to improve efficiency. To achieve net zero, existing buildings must have their energy efficiency improved, and they need to stop using fossil fuel to heat them,” says UCL’s Steve Evans who led and project managed the work.

Islington Council has now put this collaborative project with UCL into practice. The report generated by the UCL team was used as evidence in a successful bid for £4m from the Social Housing Decarbonisation Fund (SHDF), and plans are now underway to retrofit the first 400 homes. 

UCL’s Steve Evans comments: “One of the key things when you go for SHDF funding [is] they want to know very detailed specifics about your buildings and the measures needed. It’s a real challenge for some local authorities, so the report we wrote definitely contributed to that success.” 

The Building Stock Lab is putting its innovative methodologies into action across multiple projects. Following the success of its work with Islington Council, the tools and techniques used to model local heat networks are now being applied in other high-density boroughs.

Several London councils are exploring how to replicate Islington’s pioneering heat network, which captures waste heat from the London Underground to help decarbonise buildings. One new scheme is already underway.

To support wider rollout, the UCL team is enhancing its modelling tools with a new ‘cost calculator’ feature. This will allow councils to quickly adjust inputs such as labour, materials, and installation costs when planning retrofit projects.

Recognising the success of this work and other projects, UCL and Islington Council signed a Memorandum of Understanding (MoU) in 2023 to formalise their partnership and support a shared vision for a more equitable future for Islington. "We're not just a university situated nearby; we're committed to being active contributors to the heart and soul of Islington," said Professor Alan Thompson, Dean of the Faculty of Brain Sciences and Pro-Provost for London. "This partnership signifies our joint determination to make tangible, positive changes."