Improving housing energy performance

Professor Rajat Gupta

Professor Rajat Gupta is helping governments, communities and individual homeowners to understand and reduce domestic energy use and lower household carbon emissions.

Through his proprietary energy mapping software, DECoRuM® – which stands for Domestic Energy, Carbon Counting and Carbon Reduction Model – Rajat can map energy use by household and local area, helping communicate the potential for energy improvements and reduction of fuel bills..

As well as positively influencing policy and practice, DECoRuM® has been used to target energy retrofits that have resulted in real reductions in CO2 emissions, and has proved instrumental in encouraging behaviour change among householders by helping them visualise the potential of these measures to improve their household energy performance.

Award-winning carbon mapping

Abingdon CO2 emissions before and after energy retrofit
Abingdon CO2 emissions before and after energy retrofit

DECoRuM® combines energy modelling with spatial mapping to rapidly measure, model, map, manage and track energy use and CO2 emissions by household. Dynamically collecting and visualising results on an urban scale, it can be used by local authorities to accurately identify appropriate areas for targeted energy retrofit.

Using actual home characteristics gathered from a variety of sources, the system assesses energy use, CO2 reductions and the projected cost-effectiveness of targeted energy efficiency and low carbon interventions in the short to long term.

In 2006, DECoRuM® won Rajat the inaugural Royal Institute of British Architects (RIBA) President’s Award for Research.

Influencing policy and practice

As a result of his work on DECoRuM®, Rajat acted as technical advisor to the United Nations Environment Programme (UNEP), piloting and refining its Global Common Carbon Metric (CCM) approach through the Sustainable Buildings and Climate Initiative. This has since been developed as an ISO standard on carbon metrics of buildings.

DECoRuM® has been cited as an example of best practice by the UK Government’s Department for Business, Energy and Industrial Strategy, and its findings used to inform policy development in the area of community/local energy and household energy use.

Meanwhile, the Construction Leadership Council’s Green Construction Board awarded the tools and datasets created by the DECoRuM® model the highest score for future usefulness in understanding housing energy use.

Local and national impact

As part of a low carbon communities project in partnership with six areas, DECoRuM® was used to measure and communicate energy use for more than 1,800 dwellings before and after community energy projects, and to predict future carbon savings.

Drawing inspiration from the project findings, householders in one neighbourhood in Oxford were encouraged to store and share solar-generated electricity. Solar photovoltaic systems and smart batteries were installed in 82 homes, generating 117MWh per year of solar electricity and increasing self-consumption of solar electricity from an average of 51% to 65% per year.

DECoRuM® has also been used to identify fuel-poor neighbourhoods in Oxford with high energy use, and its findings used to develop a county-wide future energy planning tool.

Rose Hill, Oxford CO2 emissions before and after energy retrofit
Rose Hill, Oxford CO2 emissions before and after energy retrofit

Changing attitudes and behaviours

A further project inspired by the original, found that householders who were provided with energy feedback were more motivated to adopt energy-saving behaviours and to undertake retrofit measures, from draught-proofing to fitting solar PV panels.

These findings have been used by community organisations and community energy schemes to support bids for funding and to feed into collaborative knowledge exchange projects.

Achieving real CO2 emissions savings

Tested on three advanced low-carbon refurbishment projects as part of Innovate UK’s ‘Retrofit for the future’ drive, DECoRuM®’s findings directly contributed to carbon emissions savings as high as 80% on one project.

The software also played an important role in preparing a local community bid from the Oxfordshire town of Bicester, for the National Green Deal programme. It was used to assess the potential for applying costed refurbishment packages based on energy-saving measures and low-carbon technologies. The findings led to cavity and wall insulation being installed in 42 homes, resulting in CO2 savings of at least 50tCO2 per year.

Bicester CO2 emissions before and after energy retrofit
Bicester CO2 emissions before and after energy retrofit
Bicester PV potential (kWp)
Bicester PV potential (kWp)

Ongoing impact

DECoRuM® is currently being adapted for use in India, where it is helping to increase the use of rooftop solar panels, insulation, shading and low-energy cooling/heating systems for 2,000 homes across five cities, as part of plans to improve the energy performance of an estimated 100 million homes by 2028.