St John’s College, Porters Lodge & Central Services
Deep retrofit and decarbonisation of a listed building
Client: St John’s College
Status: Completed
OVERVIEW
This project for St John’s College involved a high-quality refurbishment of Grade II listed buildings dating back to the 18th century, transforming them into a new Porters’ lodge and office space. The works included a complete overhaul of the existing services, complete re-roofing with new tiling, insulation with Intello membrane, high-performance internal wall insulation, and a refurbished limecrete floor, all of which responded sensitively to the project conservation requirements.
Recommendations from hygrothermal analysis, which analysed the properties of the existing fabric elements, were incorporated. The majority of windows were replaced with high-specification vacuum glazing to further reduce heat demand and limit the building's heating requirement.
Heat was re-supplied using a pair of domestic-sized air-source heat pumps discreetly concealed within the landscape design. The heat pumps were configured to be reversible upon activation of a manual seasonal switchover. The same distribution circuits throughout the building could be used for space heating in winter and cooling in the summer. Fan-assisted radiator emitters were provided in rooms to provide light cooling during summer heat waves.
A mechanical ventilation retrofit with heat recovery was implemented to improve air quality and reduce heat loss through ventilation. The existing chimney flues were utilised to route new ductwork through the building, minimising the visual and heritage impacts. The new ventilation systems incorporated demand control to provide high air quality and comfort while minimising the building’s energy footprint. A limited number of hidden photovoltaic panels were also installed to meet the area's conservation requirements and provide on-site electrical generation.
The project was formally handed over to the client in 2023 and has since been fully occupied.