Wolfson College, University of Oxford

The first project of its kind in the UK, the decarbonisation of Oxford University’s Wolfson College set the unique challenge of achieving net zero carbon in a Grade II-listed piece of Brutalist architecture.

An ariel view of buildings and greenery space

Key information


Original Field


Wolfson College, Oxford



Year of Completion



At the project's outset, the graduate college had a 20-year carbon footprint of ~24,000 tonnes of CO2 across their 15,000m2 GIA buildings. After an extensive refurbishment that figure reduced by more than 500 tonnes in the first year of occupation. As of January 2024, the College had no fossil fuel combustion in its buildings and is on course to achieve net zero carbon well ahead of their 2030 target.

We undertook a study into carbon-saving measures and discussed the range of options and their carbon savings with the college. The building’s 50-year-old gas heating system, its extensive single-glazed windows and its status as a work of architectural and historical significance posed a significant challenge.

Following the study, we produced a Decarbonisation Plan that recommended: changing the single glazing to triple glazing; reusing and adapting the existing gas-fired heating system to work with electric heat pumps; replacing the roofs and installing maximum insulation; upgrading all lighting to LED and installing PVs on the new roofs and installing a 1MWh electrical storage battery.

Wolfson College, Oxford

Environmental impact

To keep disruption, cost and embodied carbon to a minimum, we devised a strategy to keep the existing radiators and pipework and worked with the college to ensure it could be occupied throughout the programme of upgrades. We opted for an air-source heat pump system, using an innovative low environmental impact CO2 refrigerant (rather than a more damaging refrigerant). The project is one of the largest CO2 heat pump programmes undertaken in the UK and one of the first to use CO2 refrigeration for space heating at this scale. We have also made many rationalisations to the mechanical systems to reduce energy consumption more generally – radically reducing pump sizes and the extent of distribution pipes.

Our calculations established that replacing windows, roofs and insulation alone has reduced the buildings’ annual heat losses by 80%. Energy consumption data over the first year showed that gas consumption reduced by more than 60%, while electricity consumption barely increased. The losses in the hot water distribution system have reduced 40%. In the first year, the reduction in pumping energy largely offset the additional electricity consumption of the heat pumps, 

The total reduction in carbon emissions is calculated to be more than 80% over the next 20 years, however the College now procures 100% renewable electricity and so the reduction in operational carbon emissions is 100%.


reduction in carbon emissions


SALIX funding acquired


reduction in annual heat loss

Heritage planning restrictions

High planning and heritage standards for the Grade II-listed building meant that choosing the correct glazing was crucial. Following extensive research by the architect Original Field of Architecture, the team opted for Cuin glass, a material that has the performance of triple glazing with the thickness of double. This allowed the heritage sightlines to be preserved without compromising the aesthetic of the building while achieving excellent thermal performance.

We led the college’s successful application to secure £6M of SALIX Grant funding, which covered 65% of the first phase works and some proportion of the second phase. We are working with the college to help them promote and explain the project to their residents and alumni, to help them secure support for the later phases of the work. 

"If heating homes is to stop heating the planet, government and industry will need to work together to bring green energy solutions to a tipping point."

Photo of person with glass and blue shirt, on a black background

Director, MEP Engineering