Real-Life Retrofits Show Best Solutions for Social Housing

Results are now providing the evidence to show how retrofit measures perform to improve energy efficiency, comfort, and affordability for social housing residents.

The results are from research undertaken at Liverpool John Moores University (LJMU) in partnership with wienerberger, providers of whole house retrofit solutions.

Real House Models

Three real-life terraced houses were constructed at LJMU to represent typical UK houses from the 1920s, 1970s and 2010s.

Each test house was given a full whole-house retrofit using wienerberger’s Renatus solution, involving different combinations of measures. They included building fabric upgrades, airtightness improvements, ventilation enhancements, solar roofing and low-carbon heating including air source heat pumps.

Wienerberger’s inline solar roofing system was also installed to test the impact of different roof build ups and roofing underlays.

Researchers installed numerous high-response sensors to monitor energy use, indoor comfort, and operational costs across the different housing types.

The results show that the 1920s house achieved the highest Energy Performance Certificate (EPC) rating gains.

The 1920s property rose from EPC D to EPC A, while the 1970s and 2010s homes improved from EPC C to EPC B.

Solar Roofing

Solar roofing was the retrofit measure that had the biggest standalone impact, suggesting that this measure should be included as a minimum when roofs are being replaced.

Importantly, the retrofit works were sequenced to replicate real-life conditions, showing that upgrades can be delivered while residents remain in their homes, minimising disruption. Advanced monitoring, including simulations of tenant behaviour, provide accurate long-term data on energy consumption, indoor air quality, and moisture levels.

The Renatus test houses provide a replicable model for social housing providers seeking to meet EPC targets, reduce carbon emissions, and deliver tangible benefits to tenants through evidence-driven retrofit solutions.

The evidence is important for social housing providers who face significant funding gaps for retrofitting housing stock meaning they must prioritise the most energy efficient measures to optimise their budgets.

John Harris, Head of Social Housing at wienerberger, said: “Social housing providers face the dual challenge of improving energy efficiency while keeping homes healthy, affordable, and practical for tenants. The Renatus test houses demonstrate a scalable, evidence-based approach that delivers lower energy bills, better comfort, and healthier living conditions.”

Social housing providers are landlords to approximately 4 million UK tenants and this sector is currently the largest undertaking retrofits, with 2.3 million homes that do not achieve an EPC target rating of ‘C’, the aim for all rented homes by 2030.

“It’s important that we understand what the social landlord wants to achieve and that we have early conversations to tailor our approach on a case-by-case basis,” Manuela Fazzan, Director of Commercial Propositions said.

Renatus Process

The Renatus retrofit process has five stages, starting with installing sensors in a home to measure energy performance alongside intrusive surveys of the building fabric.

Based on the gathered data, wienerberger’s in-house architect team then formulates a design and specification to standards, aligning it with the Tenant Power energy supply offer from Octopus to reach zero energy bills – and from this point tenants can move onto the zero bill tariff.

Retrofit measures are then supplied, with inspections at each stage to ensure performance and compliance. The process ends with a performance guarantee and certification.

Manuela Fazzan added that the process aims to simplify what is commonly a complicated and fragmented process of retrofit supply.

Paul Instrell, CCO at wienerberger said, “We want to maximise the retrofit ‘bang for buck’ with an end-to-end solution and root it in the tenant experience. This is how we can add value to the social housing community.”

Professor Mike Riley, Director of the School of Civil Engineering and Built Environment, added: “This project combines academic research and industry expertise to create a living laboratory for social housing retrofit. The data we gather will help providers make informed decisions that improve both building performance and residents’ quality of life.”

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