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Heating our homes can be expensive and draughty old housing stock leaches carbon dioxide. But making homes more energy efficient can be a costly upheaval and is therefore often done piecemeal.

Tom Heap meets the team from Energiesprong who are proposing a new model - retrofitting modern technology like insulating 'wraps' around the house, replacing roof tiles with solar panels and fitting ground source heat pumps into old housing stock. It's done on scale and on a whole-house basis to keep costs down with the aim of creating net zero energy homes but also to create 'kerb appeal' so that neighbours will want to 'keep up with the Joneses'.

Tom is joined by climate scientist Tamsin Edwards to discuss whether tackling inefficient, poorly insulated housing head-on can provide great gains for people and planet.

Listen now on BBC Radio 4


What our experts say

We asked Society Fellows Professor Stephen Peake from the Open University and Kate de Selincourt, writer on environment, sustainable building and energy to offer some observations on the potential of retrofitting existing buildings to a net zero standard in reducing carbon emissions. Their points take some of the themes of the programme a step further.


What are the limiting factors?

Kate de Selincourt

  • Energy (especially gas) is too cheap in this country to make it realistic to pay for individual retrofits - of the depth and quality needed - through bill savings alone. However, if any retrofit is carried out to a low level of improvement, it makes it harder and less commercially attractive to then re-retrofit to the levels needed. Thus, we need to do retrofits that are as thorough - or 'deep' - as Energiesprong, but we will need to look more widely for options to fund them.

  • Mass retrofit can easily be afforded when the full value of the ‘co-benefits’ is taken into account, but this needs an intelligent and joined-up approach to investment in the building stock. Public investment is needed alongside private investment. But it is an investment that pays back, because there are public, as well as private, benefits.

  • Individual design by someone who understands buildings is almost always needed in deep retrofit. This has now, finally, been recognised by the government. While this adds to the upfront cost, it vastly saves in the long run, both in terms of achieving the needed savings, and in protecting the property from damage. Do it once, do it right!



What are the co-benefits?

Kate de Selincourt

As well as warmth, good retrofit can deliver better air quality, less mould and damp, and also quieter interiors. From these flow:

  • Better health, directly, and indirectly (due to more disposable income because of lower bills, and less household financial, psychological and social stress).

  • Lower NHS costs.

  • Higher attendance at work and education.

  • Higher performance in more comfortable, better ventilated offices and education settings if these are also retrofitted.

  • Lower bills and less damp and mould leads to lower arrears, lower maintenance costs, fewer complaints, and properties less often standing void – all commercial and operational benefits to landlords.

  • When buildings hold the heat longer, it makes it easier to ‘load shift’. Load shifting can match times of heating to renewable generation and spread the load on the grid, reducing peaks in demand. High peaks of demand are very expensive for the grid as you need more generation (or expensive storage) and extra transmission capacity (cables) to meet those peaks.


Professor Stephen Peake

  • Better mental health 

  • In today’s economic environment retrofitting is becoming a lot more cost effective as construction prices rise, it also uses less new embodied carbon than a new build.


Are there any potential negative impacts of this idea?

Kate de Selincourt

  • I do not think there are many downsides where Energiesprong itself is feasible and delivered with due attention to quality, moisture and fire safety, etc. (as of course is required in any construction work).

  • Energiesprong may point to an effective solution for some groups of buildings. However, there will be a lot of cases where another approach is required. It can’t be regarded as a silver bullet.


Further reading

Allen, J. and Macomber, J. (2020), Healthy Buildings on the Horizon, Harvard Public Health

BBC (1997), How Buildings Learn: Flow

BBC (1997), How Buildings Learn: The Romance of Maintenance

BBC Sounds (2017), Costing the Earth: Insulation for the Nation

Committee on Climate Change (2019), UK housing: Fit for the future?

Construction Leadership Council (2020), Greening Our Existing Homes. National retrofit strategy, a consultative document.

Grant et al. (2019), Passivhaus: the route to zero carbon? The Passivhaus Truet

Lowe, R. Chair of Energy and Building Science, UCL

Palmer, J. Cambridge Architectural Research Ltd

Selincourt, K. (2021), Deep retrofit and stimulus, Passive House + Sustainable Building

SevernWye (2020), Health Impacts of Home Energy Interventions, Summary Report, BUILD2L


About the series

39 Ways to Save the Planet is a new radio series by BBC Radio 4 developed in partnership with the Society and broadcast in 2021. It showcases 39 ideas to relieve the stress that climate change is placing on the Earth. In each 15 minute episode Tom Heap and Dr Tamsin Edwards meet the people behind a fresh and fascinating idea to cut the carbon.

Programme website

Over the course of 2021, the Society will be producing events and digital content to accompany the series.


Episode 24: Insulate the nation

Listen now on BBC Radio 4


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