Average cost for net zero retrofit almost £70k

row of terraced houses EDF

A study led by the University of Nottingham found that the average cost of an extensive retrofit would be £69,000 per house.

The Nottingham Carbon Neutral Housing: Cost vs Carbon Retrofit Roadmap project – which received £350,000 government funding as part of the UK Community Renewal Fund – involved the development of a retrofit roadmap to inform the decarbonisation of the city’s existing housing stock to help reach its carbon neutral targets by 2028; and the UK’s by 2050.

Professor Lucelia Rodrigues, project lead and Professor of Sustainable and Resilient Cities at the University of Nottingham, said:

Our retrofit roadmap has provided a unique breakdown for all different building types, and assessed what is needed to tackle housing emissions and accelerate the city’s 2028 ambitions.

We’ve discovered that the cost of ‘deep retrofit’, retrofitting a home to the highest levels of energy efficiency, is at least double the expected amount – averaging around £69,000.

We’ve also learned that, for most homes, it is both more cost- and carbon-effective to first improve the building’s fabric before electrifying heating.

Additionally, the study has revealed that 14,539 no-income Nottingham homes could mistakenly not be considered as fuel-poor. This means that these have been missed from the government’s current estimates that suggest the total number in Nottingham to be in the region of 35,000.

Since receiving funding in November 2021, the university and its project partners, Nottingham Energy Partnership, Focus Consultants and the Active Building Centre Research Programme, have explored the energy and carbon reduction benefits of a series of retrofit strategies to improve typical existing housing, taking a sequential approach based on likelihood and feasibility. An assessment of cost and carbon-effectiveness of the retrofit interventions has also been produced, accounting for embodied carbon of fabric improvements and heating systems. It is the first time all these elements have been considered together at this scale.

Councillor Sally Longford, Portfolio Holder for Energy, Environment and Waste Services at Nottingham City Council, said:

I welcome the findings from the University of Nottingham’s retrofit roadmap study. Through our experience with whole-house retrofit projects, we could see that the UK government’s estimate of £30,000 per household would not be sufficient to fully future-proof homes in the city in line with net-zero standards.

Heating and powering buildings in the city accounts for the largest proportion of Nottingham’s carbon emissions. We have been making good progress on improving the energy efficiency of homes through our various Greener HousiNG schemes, which has led to 44.8% reduction in CO2 emissions from the domestic sector since 2005. Much of the city’s housing stock was built before 1990 – with poor insulation and fossil-fuel based heating being widespread – so it is vital that we’re able to roll out retrofit projects at scale if we are to reach our ambitious target of being a carbon neutral city by 2028.

I hope this research will encourage the government to commit to providing long-term funding for retrofit schemes. This will allow us to tackle fuel poverty and improve the quality of life for people in the city, while working towards our CN28 goal.

To view a breakdown of carbon and cost implications of retrofit strategies per home archetype and age, visit: nottinghamcedi.org/downloads/