Lighting the path to a greener future

Image: Nick Saffell

Image: Nick Saffell

King’s College Cambridge has completed work on a year-long conservation of its Chapel roof and has begun installation of 438 new solar panels. Restoration of the Chapel roof had become increasingly urgent once its lead roof covering exceeded its natural lifespan, meaning it was no longer watertight. The College recognised a once-in-a-generation opportunity to both completely restore the roof and install photovoltaic (PV) panels while the necessary infrastructure was in place, as the Chapel roof is the single largest potential opportunity for renewable electricity generation on the main College site.

“This is an historic moment for King’s College Chapel and Britain’s architectural heritage. It is only one step on the road towards cleaner, greener energy but it is a potent and inspirational symbol of our commitment to being good stewards of our environment.”
Dr Gillian Tett, Provost of King's College

After an extended period of consultation with bodies including the Diocesan Advisory Commitee (DAC) of Ely Diocese, Historic England and the Society for the Preservation of Ancient Buildings, Cambridge City Council unanimously approved the College’s proposal for the PV installation. Work on the roof restoration began in September 2022 and PV installations are now underway.

Image: Nick Saffell

Image: Nick Saffell

Shane Alexander, College Project Manager, said: “The installation of the panels has been designed to dovetail with the crucial conservation works to the Chapel roof. The restoration required that the entire lead covering was removed, recast and replaced, all while maintaining access to the building for visitors, daily services and concerts. The project was extraordinarily complex and has been delivered by a fantastic team.”

A temporary roof was installed with carefully designed scaffolding so the lead and timbers could be removed without risk to the inside of the Chapel.

After recasting in Leicestershire, the lead was installed and work on the photovoltaic array infrastructure could begin

The first panels were installed once the roof scaffolding was completely removed

The PV installation is scheduled to be complete by the end of 2023.

Arrays of 219 REC Alpha 420 Pure-R photovoltaic panels will be fixed to each of the north and south slopes of the Chapel roof and will generate an anticipated 123,000 kilowat hours per year (kWh/y) which feeds into the College’s on-site electricity supply. Total potential peak output of the panels is 100 kWp.

The photovoltaic panels, which form one facet of the College’s strategy to decarbonise its operations by 2038, will reduce the College’s carbon emissions by more than 23 tonnes each year, the equivalent of planting 1090 trees. The new panels, combined with existing panels installed on the Wilkins Building and Old Garden Hostel student accommodation, will reduce the annual electricity demand of the College’s main site by approximately 5.5%.

Take a behind-the-scenes look at the restoration work:

Aerial footage courtesy of Sky Revolutions Ltd and Barnes Construction

Aerial footage courtesy of Sky Revolutions Ltd and Barnes Construction

The Chapel joins a number of churches and cathedrals which have already installed solar panels, including Salisbury and Gloucester Cathedrals and Great St Mary’s, the University of Cambridge’s church. The project has been exclusively funded by philanthropic donations made to the Chapel and College over many years.

"Whilst the economic input of the solar panels are valuable in monetary terms, its main public benefit is in the carbon saving over a period of many years. It must also be seen as part of the College’s drive to make its buildings and especially the Chapel more efficient and as a tangible example of how the Chapel can and should be contributing to the moral and ethical wellbeing of this place of learning.”
Rev Dr Stephen Cherry, Dean of King's College Chapel

The project has been delivered by Caroe Architecture Ltd and Barnes Construction, working in partnership with a number of regional firms with experience of historic conservation and reclaimed materials.

Oliver Caroe, heritage and conservation-accredited architect for the project, commented: “This has been a fascinating and exemplary project. The lessons learned on this project and the example of what can be achieved is already inspiring and informing others, which fully reflects the research and academic goals of the University. In addition, the exemplary and highly principled leadership given by the College Fellowship and team is to be commended.”

Conservation and craftsmanship

Local labour

Norfolk Sheet Lead carefully installed the lead roof, made from...

Reclaimed lead

...145 tonnes of reclaimed lead, recast in Leicester by the UK's only remaining firm to use traditional sand casting.


Cambridge stonemasons Hibbitt Masonry carried out repointing and replacement of high-level stone sections and have a long association with the Chapel.


Side Chapel oak timber was repurposed and reused wherever possible and timber works have been carried out by local firm Richard Glover Carpentry.

Image: Nick Saffell

Image: Nick Saffell

Mark Hart, Joint Managing Director at Barnes Construction said: “This unveiling marks a significant milestone for the project, as we progress with the installation of photovoltaic panels to the roof of one of the most important and most recognisable buildings in the UK and across the world. It is a great honour to be part of not only preserving our cultural heritage but championing sustainable practice in such an iconic setting. The work involved in restoring the roof to its original splendour demonstrates a profound respect for history, whilst the installation of photovoltaic panels provides a clear message regarding the college’s dedication to its environmental responsibilities. Moreover, the work being done illustrates that honouring our past need not come at the cost of our planet’s future. We are immensely proud of our association with this project and sincerely hope that the success of the scheme will encourage similar endeavours that promote sustainability in historic buildings.”

A more sustainable King's

Alongside retrofitting and improving its historic buildings, King's is conscious of the need to construct new buildings to the highest current environmental standards.

The College has already replaced old boilers in student accommodation like Spalding Hostel with ground source heat pumps. Photovoltaic panels are already installed on several of the College’s buildings, including the Wilkins Building, Stephen Taylor Court and Old Garden Hostel.

New graduate student accommodation on Cranmer Road, completed in 2022, was designed by architects Allies and Morrison to Passivhaus standard and in harmony with surrounding buildings in a designated conservation area.

The thermal efficiency of the buildings delivers secondary benefits by obviating the need for large plant spaces and so maximising usable space.

The project won a RIBA East 2023 Award , which recognises "a UK project for its regional importance as a piece of architecture."

"The jury was impressed by the level of ambition, rigorous technical design, innovation and refinement of detail in this pioneering project. As the University of Cambridge and the colleges aim to decarbonise their estate over the coming years, the Cranmer Road project will provide a pointer to some of the techniques and approaches to be followed and developed."
RIBA Regional Jury, 25 May 2023