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Reflections on DEEP Retrofit Research Project with John Bonning

14 Jul 2023

Gain insights from an interview with John Bonning by Laura Broderick, reflecting on a day of 'DEEP' seminars at Leeds Beckett University on June 23rd, 2023, featuring the latest research findings on how to deliver safe and effective retrofits in solid wall homes. 

Laura Broderick (LB): What is the DEEP project?

John Bonning (JB): The Demonstration of Energy Efficiency Potential (DEEP) domestic retrofit research project is the largest of its kind ever undertaken in the UK and was funded by the Department for Energy Security and Net Zero (DESNEZ). The project was led by Leeds Beckett University (LBU) in collaboration with the University of Salford and Loughborough University and is featured in the Retrofit 23 exhibition at the Building Centre. 

Focusing on a fabric-first approach to residential retrofit, having adapted and studied 14 solid-walled homes between 2019 and 2022, researchers on 23rd June shared findings on:

  • Piecemeal and whole-house approach to retrofit 
  • Safe and effective ways to retrofit solid wall homes  
  • Measured vs modelled energy performance 
  • Practicalities and cost of installing retrofits 
  • Dealing with overheating

LB: How was the launch event?

JB: It was great! I was delighted to have been invited to the DEEP retrofit research project presentations. It was a full-on conference day, carefully orchestrated by Professor David Glew with a stellar cast of speakers from academia and industry. The campus was also inspiring – the Carnegie School of Sport venue was a fantastic setting with superb facilities.  

LB: What’s been your involvement with the LSI?

JB: Well, we have had the pleasure of working with Leeds Sustainability Institute (LSI) at LBU as our academic partner for Retrofit 23 knowing they were conducting a comprehensive research project on fabric-first retrofit measures of solid walled homes.  They conducted various retrofit measures on 14 homes in the Yorkshire area and analysed the outcomes. The research looked for the most effective retrofits for solid-walled homes, together with assessing technical risks, implications of choosing a whole-house approach, and more.  

LB: What are your key takeaways from the presentations and research findings?

JB: External wall insulation (EWI) is the only measure to achieve significant efficiency in the solid-walled home. Other measures such as loft insulation, internal wall insulation, improved glazing and insulation for suspended timber floors have less impact. I expected greater increased efficiencies from all the retrofit measures, so it was interesting to consider what to prioritise in residential retrofits going forward.  

Also, I was attentive to the discussion around the use of the term ‘retrofit’ and whether using terminology like ‘home improvement’ and/or ‘better buildings’ would be more useful and more meaningful to all of us, especially when trying to get more people involved in making changes to their homes for their own health and long-term financial benefits.  

Costs also came into discussion, and general maintenance of a building over a number of years will significantly vary and affect any retrofit budget. But we need to get it right for each home, with the correct products and installation carefully considered and carried out. Some piecemeal retrofit solutions were effective in saving energy in the homes tested, though of course, everything is on a case-by-case basis – no two homes are the same!  

LB: What about the Building Centre’s role?

JB: Well, as Emeritus Professor Malcolm Bell (LBU) said in his wonderful closing presentation, “The housing carbon/energy challenge is bigger than we think, even though we know that it is bigger than we think.”  

I hope the Building Centre’s work with Retrofit 23 is also supporting the conversation – we understand it is hard for most homeowners, tenants and landlords to know where to start and what to prioritise when the cost of living is so high. Still, we want to save energy for ourselves and the planet. Hilary Benn MP and leaders from the National Retrofit Hub spoke at the event too, which was great. It’s going to be down to policymakers and organisations to make the challenge manageable for individuals.  

LB: How can people find out more?

JB: The full official DEEP report will be available later in the summer but for now you can watch their introductory video online. Or visit the Building Centre of course! We would love to welcome you; it’s been fantastic to have LBU as our educational partner this year. 

If you can’t make it in person you can review the content via the Retrofit 23 exhibition walkthrough that we have produced, you can view it now. 

Our past events were recorded and can now be watched on our website. We hosted the team from LBU, University of Salford and Loughborough University at the Building Centre for an event, Retrofit Meets: Solid-walled Homes', as part of the Retrofit 23 public programme.

We have more exciting events lined up in the coming months discussing community action, well-being, financing and upskilling. All events are free, so we encourage you to book now.



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