Study shows retrofits vary hugely home-to-home

A unique retrofit project has highlighted the scale of the challenge to improving Britain’s housing stock and cut home heating bills.

Updating building fabric and insulation and installing systems like solar panels and air pumps can cut energy bills by almost 40%, according to studies at Liverpool John Moores University.

However, results vary massively between properties, reinforcing the importance of understanding each home's starting condition and tailoring retrofit measures accordingly.

A new report by LJMU and wienerberger UK & Ireland, aimed at social housing providers, offers unique insights into the performance of efficiency upgrades, comparing retrofits to homes of different ages and types.

It concludes that retrofit can deliver significant improvements for occupiers – but the results are not the same for every home, and success needs to be measured in more than one way.

LJMU and Wienerberger have been studying the impact of retrofits packages on homes built in the 1920s, 1970s and 2010s at the university’s Home Testing Laboratory.

Dr Hu Du, Reader in Building Performance at LJMU said: “If social housing providers are to invest the huge sums needed in improving its housing stock and reducing long-term maintenance, they need better data on how retrofit works in the real world.”

A living laboratory

The project saw retrofits to three test houses using wienerberger’s Renatus retrofit and drawing on expertise from its in-house architect studio.

Improvements were made to the building fabric, external wall insulation, heating and renewable energy systems – all tailored to the individual property. Air source heat pumps were introduced in the 1970s and 2010s properties, while all three homes incorporated solar PV.

Dr Du and his colleagues measured performance of the retrofitted properties over a 12-month period – with results published for energy demand, operational carbon emissions, running costs, heat loss, EPC rating improvements and estimated carbon payback.

Energy demand fell across all three properties, while operational carbon emissions decreased by an average of 85.5%. Annual running costs also fell by an average of 39.2%, once income from exported electricity was included.

However, the results varied considerably between the properties, reinforcing the importance of understanding each home's starting condition and tailoring retrofit measures accordingly.

Delivering improvements

Paul Instrell, chief commercial officer at wienerberger UK & Ireland, said: “Retrofit is ultimately about improving the quality of people's everyday lives – helping to deliver warm, healthier and more comfortable homes that are more affordable to run.

“But with such a varied housing stock, there is no single ‘typical’ home to tackle. A solid-wall property built almost a century ago is fundamentally different from a post-war cavity-wall home, while a more modern house starts from a very different position again.

“This research shows that retrofit can deliver significant improvements, but the results are not the same for every home.”

The Retrofit in the Real World report is available to download for free.