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Retrofit Revisit is an important building performance evaluation project to inform the UK’s approach to improving our housing stock and contribute to our net zero objectives. This publication details a building performance evaluation of 10 retrofitted homes, carried out approximately 10 years after the original retrofit works. It aimed to gather lessons on retrofit and on BPE techniques.
On retrofit:
• What has stood the test of time?
• Are there any new lessons on how to carry out retrofit projects?
• Topics of particular interest included (but were not limited to): energy demand, moisture, insulation options (moisture and combustibility), degradation of original solutions (e.g. airtightness).
On BPE techniques:
• What can be learned in a relatively short and non-intrusive manner, from individual BPE techniques or packages of several techniques?
• Where are more specific or detailed BPE techniques useful? How can some BPE techniques being, or newly, developed help?
The sample of 10 homes was as follows:
• Six were part of the 2009 Retrofit for the Future programme. All were considered best practice or exemplar at the time, and employed a whole house 'deep' retrofit approach.
• Six were pre-1919 properties.
• Nine were houses, one a flat.
• Some were tenanted from housing associations, others occupied by private owners.
• The insulation strategies and properties varied, with a mix of external, internal, and cavity insulation and of permeable and impermeable materials.
• Heating, hot water and ventilation systems were very varied across the sample.
A two-tiered BPE approach was followed, which is detailed fully within the publication.
Executive summary
Abbreviations
Foreword
Cross-project briefings
Briefing 1: BPE overall approach
Briefing 2: Energy use: current performance and evolution over time
Briefing 3: Airtightness: performance, solutions and evolution over time
Briefing 4: Thermal layer
Briefing 5: Construction details: corners, junctions, edges and interfaces
Briefing 6: Indoor environmental quality
Briefing 7: User experience
Briefing 8: Maintenance
Briefing 9: BPE techniques: airtightness testing
Briefing 10: BPE techniques: thermal and moisture evaluation techniques
Case studies
CS1 Blaise Castle
CS2 Hawthorn Road
CS3 Grove Cottage
CS4 Culford Road
CS5 Hensford Gardens
CS6 Rectory Grove
CS7 Princedale Road
CS8 Shaftesbury Park Terrace
CS9 Wilmcote House
CS10 Passfield Drive
References
Appendices
Appendix 1: Briefing to evaluators and BPE methodology
Appendix 2: Residents' briefing and consent form
Appendix 3: Comparison of BPE methodology with BS 40101:2022
Appendix 4: Domestic occupant satisfaction surveying
Appendix 5: Detailed testing: moisture
Appendix 6: Hawthorn Road: hygrothermal risk analysis report
Appendix 7: Shaftesbury Park Terrace: hygrothermal risk analysis report
Appendix 8: Hawthorn Road: hygrothermal risk analysis report
Appendix 9: Results from fungal testing and visual inspection
Authors: Julie Godefroy and Marion Baeli
Key funding partner:
Innovate UK
Funding partner:
Historic England
Support and funding:
10 Design
Studio PDP
In-kind support:
BPE Testing and Experts
Build Test Solutions
Paul Jennings
Qoda
Leeds Beckett University
Loughborough University
UK Centre for Moisture in Buildings
BPE evaluators
Justin Bere, Bere Architects
Nuala Flannigan, Warm
Helen Grimshaw, Carbon Coop
Andy Macintosh, Feilden Clegg Bradley Studio
Ian Mawditt, Four Walls
Lilija Oblecova, ECD Architects
Bob Prewett, Prewett Bizley
Mike Roe, Warm
Lizzy Westmacott, ECD Architects
Tim Wilcockson, Qoda
Joe Jack Williams, Feilden Clegg Bradley Studio
Steering Group:
David Allinson, Loughborough University
Caroline Cattini-Dow, Historic England
Zack Gill, Soap Retrofit
David Glew, Leeds Beckett University
Sally Godber, Warm
Marianne Heaslip, People Powered Retrofit
Valentina Marincioni, UCL & UK Centre for Moisture in Buildings
Loreana Padron, ECD architects
Sarah Price, Spruce (previously at Qoda)
Rokia Raslan, UCL
Hannah Reynolds, Historic England
Peter Rickaby, Peter Rickaby
Kate Simpson, Imperial College
Morwenna Slade, Historic England
Lynne Sullivan, National Retrofit Hub
Luke Smith, Build Test Solutions