Retrofit for the Future: a decade of energy efficiency success

Testing energy efficiency refurbishments 10 years on

With over 28 million UK homes needing decarbonisation, progress has been slow partly due to doubts about retrofit benefits. In 2011, Innovate UK invested £15 million in the Retrofit for the Future programme, with over 100 homes being refurbished to cut carbon emissions by 80%. As we work to decarbonise heat in our buildings, lowering energy demand through retrofit is vital.

The Net Zero Heat team wanted to find out how homes in the programme perform a decade later. With Innovate UK funding and support from a team of expert building performance evaluators, co-authors Julie Godefroy and Marion Baeli have revisited 10 homes. Looking at a variety of dwelling types, some heritage, some more modern, all with different design approaches and systems, they found sustained success and satisfied residents.

Exploring modern building performance evaluation

Retrofit for the Future had an emphasis on testing the performance of the buildings. Ten years on, techniques and technologies have changed. We wanted to know what a non-intrusive, but robust and useful, building performance evaluation (BPE) programme looks like now. This is an important question, because data from buildings will motivate future retrofits, aiding decision-makers, financiers and occupants to understand what the impact of potential interventions would be.

The Retrofit Revisit team devised a programme to assess energy usage, building fabric, airtightness, internal conditions, moisture risk, and, using the SOAP Retrofit’s survey, occupant satisfaction.

Key findings from the dwellings

The report’s findings are encouraging. Despite different designs and systems, all homes maintained good energy usage, performing better than pre-retrofit and better than average homes. While heating and ventilation system control usability wasn’t perfect, it didn’t affect overall satisfaction. Winter comfort was high, and energy bills were considered manageable by residents, despite rising prices. Summer comfort was less optimal but still met SOAP Retrofit’s benchmarks. The study also addressed concerns about health impacts from energy-efficient retrofits, finding that the homes remained within recommended bounds for indoor environment conditions.

Some standout lessons include:

• Simple maintenance tasks like clearing gutters are crucial.
• Complex systems fail more frequently.
• Mechanical Ventilation with Heat Recovery (MVHR) systems proved reliable when designed and commissioned well.

Quantifying the benefits of retrofit will help us reach our net zero targets

As Innovate UK continues to support the decarbonisation of our built environment, this report aids our mission to provide certainty and confidence in retrofit; energy demand was lowered (considerably compared to average housing stock), while the homes provided comfortable conditions, and these benefits have lasted for more than 10 years. Measuring the buildings and impact of home refurbishments will provide clarity and reassurance to occupants, investors, and decision-makers. This work will inform those wanting to use building performance evaluation themselves to create compelling cases for retrofit.

The report is extensive and usefully divided in the various building characteristics tested, including case studies for each dwelling. Those interested in how to do retrofit and its long-lasting outcomes, as well as those wanting to test these on their own buildings or projects, are encouraged to explore this report.

Register for a free CIBSE account and read the full report below. You can also register for a Building Performance Network workshop, supported by Innovate UK, on 9 October 2024 to learn more about BPE techniques.