St John’s College, a prestigious constituent college of the University of Oxford, has transformed a unique area of disused garden space into a brightly-lit semi-subterranean building by featuring a range of made-to-measure skylights from flat-roof skylight specialist, Sunsquare.
The installation was part of a redevelopment of the college’s grounds located within the Grade II listed gardens, which saw dilapidated greenhouses and storage sheds transformed into a functional new 60 sqm building – a space for gardening staff to use as an office and break room, as well as a greenhouse area for growing college plants.
Oxford-based architects Jessop and Cook were set the task of designing a building that would sit in a small horseshoe-shaped space, set within three listed walls inside the college’s tranquil gardens. Not only did it need to be completely unobtrusive – remaining unnoticed by passers-by – it also had to be aesthetically pleasing for any buildings that overlook it. This includes on-site student accommodation and the new St. John’s College library study centre, which completed in 2019. Because the area was completely enclosed by neighbouring walls, bringing in natural light was another core part of the design.
Martin Shaw, Associate at Jessop and Cook Architects, explains: “The brief from the St. John’s works team was to create a much-needed space for the college’s gardeners to use, but there were several question marks around the viability of the site. The former greenhouse and storage space was very small and almost completely enclosed, so we ran the risk that any new facilities would feel cramped and poorly lit.
“To combat this, we needed to find a skylight large enough to cover the majority of the roof space – opening it up and allowing in plenty of natural light, whilst also fitting with the building’s design and creating the right growing conditions for the greenhouse area. We were already familiar with the Sunsquare range, and we opted for a purpose-designed part-fixed, part-opening rooflight because it matched perfectly with the building’s low pitch, but still ticked our boxes when it came to thermal performance, safety and functionality. It was efficient enough to keep the gardeners warm in the winter, with an opening mechanism to provide much-needed ventilation in the summer.”
Jessop and Cook’s drawings for the upgraded gardeners’ area featured a new entrance at one end, with toilets, a shower, a breakroom and an office inside, as well as a central greenhouse section. They also included plans to excavate and lower the ground level by 800mm, to create a comfortable floor to ceiling height internally (but not enough to be seen over the college’s external wall). Here the team specified a 2620mm x 4250mm Sunsquare part-fixed, part-opening rooflight, positioned above the greenhouse area to provide the majority of the building’s natural light. Jessop and Cook also opted for two smaller 1400mm x 2000mm Sunsquare Aero Vent skylights over the breakroom. Each Aero Vent was fitted with an easy-to-control electric opening and closing mechanism, for immediate and convenient access to fresh air.
Martin Shaw continues: “One of the main challenges we faced was that the new facilities had to be completely unobtrusive and invisible from outside the garden walls. The brief was to ensure the building was completely hidden from views of the listed garden! As flat-roof skylight specialists, we believed Sunsquare had the experience to create a skylight with a pitch low enough that it would match the pitch of the roof with a minimal upstand, allowing the building to remain unseen from outside the grounds and eliminating the risk of water pooling. This, combined with the option to customise each rooflight to meet the space’s exact needs, made Sunsquare the most suitable choice.”
As well as aesthetics, the specification of the glass used within the rooflights was also a major concern. Because the new building sits slightly lower than the adjacent wall, with a green roof surrounding the skylights, Jessop and Cook had to consider the eventuality of someone gaining access to the roof. As the only rooflights in the world to hold a BSI (British Standards Institution) Kitemark for safety, the Sunsquare range provided the reassurance the college needed.
Sunsquare was also able to produce the large part-fixed, part-opening rooflight without its standard laminated glass – allowing for the UV transmission and solar gains needed to create the right growing conditions in the greenhouse area. This was done without compromising on thermal performance, with each rooflight frame boasting three thermal breaks to conductivity (providing an effective barrier between internal and external temperatures).
Mark Lambert, Sales Director at Sunsquare, comments: “We’re very proud to have been involved in such a forward-thinking project – working closely with architects Jessop and Cook to create custom-made flat-roof skylights that help get the best out of St. John’s College’s new space. Not only do they provide an abundance of natural light for rooms that need it most (especially in the greenhouse area where solar gains are so important), they also deliver the safety and thermal performance that’s needed for this unique build.
“The brief for the new space was an unusual one, and the result is a stunning but subtle finish. If you didn’t know the building was there you might never see it! But the St. John’s garden staff can now carry out their daily duties in the comfort of natural light, shielded from the cold in winter but also with plenty of access to fresh air when they need it. The building fits in seamlessly with its surroundings and our skylights have helped maintain the architectural heritage of the college, whilst adding the comforts of modern-day technology.”
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