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Driving investment into affordable, low-carbon housing across Wales

Our researchers at the Welsh School of Architecture have designed and built the first affordable low carbon house in the UK using market available technologies. Our ‘whole house’ approach to has led the to Welsh Government investing £91 million to incorporate sustainable designs into over 1,400 new homes.

The world climate crisis has forced many countries to think about what we can do to reduce carbon emissions. Homes in the UK generate 20% of the national CO2 emissions meaning that affordable low-carbon housing is critical to reducing emissions enough to meet the 95% Welsh Government target. Our research has addressed these issues by developing a ‘whole house’ methodology that can be replicated at an affordable cost for both retrofits and new build homes.

Developing a ‘whole house’ retrofit methodology

In 2009-10 our researchers investigated the possibility of reducing carbon emissions in housing by reducing energy demand by improving the materials of housing and using more energy efficient technologies. Through the Technology Strategy Board ‘Retrofit for the Future’ programme our research team applied a ‘whole house’ retrofit to a 1980s urban semi-detached house. We demonstrated that by integrating low-energy technologies into the building structure, costs could be reduced. Our analysis of the household energy use between October 2011 and May 2012 revealed a 74% reduction in CO2 emissions after the retrofit.

Our research then expanded to evaluate the possibility of using the ‘whole house’ systems-based approach on more existing Welsh homes. Funded by the Low Carbon Research Institute (LCRI) and supported by the EU Convergence Programme our researchers led the planning, design, implementation and evaluation of an affordable and replicable approach to retrofit five houses that were viewed to represent housing types across Wales. Depending on the needs of each building, the five houses were retrofitted with wall and loft insulation, double-glazing, MVHRs, PVs and energy storage technologies, and were monitored for actual energy use before and after the retrofit. Our research found that across the five retrofitted houses, CO2 emissions were reduced by 50–75%, with annual cost savings of between £402 to £621 for each household.

The SOLCER House

Alongside the retrofits, our researchers also applied a low-carbon and affordable ‘whole house’ systems-based approach to new builds which resulted in the planning, design and construction of the SOLCER House. Completed in 2015, it was the first affordable energy-positive house built in the UK. Our researchers were involved in extensive monitoring and computer simulation over a 4-year period that demonstrated that the SOLCER House generated more energy per year than it requires for heating and electrical power under normal occupancy conditions, leading to energy cost savings of around £1,000 per year. The SOLCER House won the Breakthrough Project Award at the UK Buildings and Energy Efficiency Awards 2015 and Sustainable Project of the Year at the Cynnal Cymru Awards 2015.

Informing the Welsh Government on decarbonising housing

In 2017 we then undertook commissioned research for Welsh Government on decarbonising existing housing. In the ‘More | better’ report we recommended that Welsh Government should fund exemplar housing projects to support our recommended delivery pathways and construction techniques and encourage widespread adoption of the construction of affordable low-energy housing.

In 2018 we were commissioned by the Welsh Government to review solutions for decarbonising existing housing stock through case studies of low-carbon retrofit and new- build projects. Our report used modelling to recommend ways to decarbonise Welsh housing for fourteen housing types prevalent in Wales.


Key facts

  • Homes in the UK generate 20% of national CO2 emissions
  • Completed in 2015 SOLCER house was the first affordable energy-positive house built in the UK.
  • Our research found that across five retrofitted houses, CO2 emissions were reduced by 50–75%

Our research on the viability of decarbonisation retrofits led the Welsh Government to initiate two low carbon housing programmes:

The Innovative Housing Programme

The Innovative Housing Programme (IHP) launched by Carl Sargeant AM was initially a £10million government grant scheme to build new affordable housing across Wales focused on promoting low-carbon and energy-positive housing designs. Many IHP-funded projects have drawn directly on the innovations and principles developed through our research on the SOLCER House, leading to lower energy costs and reduced year-on-year carbon emissions. Examples of homes built through the IHP that incorporated SOLCER-demonstrated principles include:

  • Forty-six homes constructed by Carmarthen County Council.
  • Over one hundred homes built by Swansea Council, who commissioned the WSA to model the impact of a new low carbon standard for its newly built homes.
  • Sixteen homes constructed by Pobl Social Housing in Neath to reduce fuel poverty for housing association tenants through net-positive housing schemes.
  • Fourteen homes in Bridgend, commissioned by Wales and West Housing.
  • Two houses built by a developer in Xi’an in the Shaanxi Province, China after a visit to SOLCER house in 2015.

£9.5m Optimised Retrofit Programme

In August 2020 Welsh Government announced a £9.5million Optimised Retrofit Programme (ORP) to install energy efficiency measures in up to 1,000 homes owned by registered social landlords and councils. The ORP includes funding for Welsh School of Architecture -demonstrated technologies, including heat-pumps, intelligent energy systems and solar panels. The ORP is now part of Welsh Government’s “green recovery” to mitigate the economic effects of the COVID-19 pandemic. The ORP has wider scope to enhance the local economy by creating local jobs, training and apprenticeship opportunities and supply chains as part of a new Welsh retrofit industry.

"It was clear to me that traditional approaches to house building would be very unlikely to deliver the changes needed. A new, innovative approach was needed and the report I commissioned from the Welsh School of Architecture demonstrated that, although there is no silver bullet, there are many potential models and methods available.”

Carl Sargeant AM, Secretary for Communities and Children.

Jones, P. J., Lannon, S. C. and Patterson, J. L (2013) Retrofitting existing housing: how far, how much? Build. Res. Infor., 41 (5) pp. 532-550

Jones, P.J ,Perisoglou, E and Patterson, J.L (2017) Five-energy retrofit houses in South Wales. Energy and Building 154, pp. 335-342

Jones P.J, Xiaojun, Coma Bassas, E, Perisoglou, E and Patterson J.L(2020) Energy positive house: performance assessment through simulation and measurement. Energies 13 (18), 4705

Green, E. Lannon, S. Patterson, J.L and Iorwerth, H. (2019). Homes of Today for Tomorrow STAGE 2: Exploring the potential of the Welsh housing stock to meet 2050 decarbonisation targets. Cardiff: Cardiff University. Available from HEI on request.