King’s College Cambridge unveils new solar panels on restored Chapel roof - Barnes Construction

Historic first for the Grade-I listed Chapel, balancing preservation with photovoltaic power generation

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 and timbers exceeded their 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 and its Chapel,” commented Provost Dr Gillian Tett. “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.”

After an extended period of consultation with bodies including Historic England and the Society for the Preservation of Ancient Buildings, Cambridge City Council unanimously approved the College’s proposal for the PV installation and work began in September 2022.

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, recasted 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.”

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 kilowatt hours per year (kWh/y) which feeds into the College’s electricity supply. Total potential peak output of the panels is 100 kWp and the monetary value has been calculated as in excess of £250,000 over their three-decade lifespan. The calculated financial payback with electricity cost of 14p/kWh was approximately 15 years, while the CO2 payback is approximately 6 years.

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%.

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.

The Reverend Dr Stephen Cherry, Dean of the Chapel, commented:

“Whilst the economic input of this PV proposal is 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. It’s a tangible example of how the Chapel can and should be contributing to the moral and ethical wellbeing of this place of learning.”

The project was delivered by Caroe Architects, 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.”

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.”