Stanton Williams’ courtyard development at Emmanuel College, Cambridge is a serene composition of spaces underpinned by a furiously hardworking and material-efficient concrete structure. By Nick Jones
Young’s Court is the most significant development at Emmanuel College, Cambridge for over a century, and it has been designed to last well beyond the next. The 5,770m2 scheme comprises three interlinked three-storey blocks of 50 student rooms, forming a courtyard in the south-eastern corner of the college grounds.
The facades of warm red brick and precast concrete suggest an air of permanence not dissimilar to the college’s 18th-century stone-faced Front Court. Inside the new buildings, this impression is confirmed, with exposed soffits revealing a solid structure of reinforced concrete. “Cambridge colleges build for the long term, which is why we’ve used robust, long-life materials,” says Alex Buckland, senior associate at architect Stanton Williams.
Emmanuel College had ambitious carbon targets for the project, with structural engineer Smith and Wallwork charged with assessing embodied carbon at every RIBA stage. The choice of a reinforced concrete frame was the result of a rigorous analysis of different structural solutions, which considered both embodied and operational carbon. When 2050 and 2080 climate scenarios were factored in, an airtight, thermally massive concrete structure offered the advantage of being able to accommodate rising temperatures without the need for additional mechanical cooling.
The crucial next step for the engineers was to maximise the efficiency of the structure, so that it required as little material as possible. “Material use is one of the big drivers for us, rather than carbon on its own,” says Mike White, associate at Smith and Wallwork. “A lot of the carbon data is still quite new, so we generally find it’s more reliable to focus on material volumes. If you reduce those, the carbon goes with it.”
Because it was responsible for the whole civil and structural design, from the piling to the reinforcement in the precast lintels, the firm could optimise the foundations and superstructure as a single interdependent system. Every column and beam has been exploited to near full capacity, and an innovative raft foundation uses the weight of the concrete frame above to counteract the “heave” of Cambridge’s Gault clay soil.
The buildings also have high levels of insulation, supplemented by natural cross-ventilation and shading, and the cooling effect of exposed soffits in the bedrooms and communal kitchens. The facades are self-supporting, reducing the opportunities for thermal bridging to the main frame. Embodied carbon, meanwhile, is further reduced through the use of 50% GGBS in the structural concrete, and was measured at 1,902tCO2e (A1-A5).
The soffits are part of a restrained interior palette dominated by white painted walls and lye-bleached Douglas fir joinery. The exposed elements had the same specification as the rest of the frame and were cast against phenolic-filmed ply formwork. The thermal mass effect is accentuated through the use of ventilation panels next to the bedroom windows, and low-energy extraction via a bulkhead above the en-suite bathrooms.
Young’s Court replaces an expanse of surface parking, which was hidden away behind a 1960s student housing block. Parking spaces have been reduced by more than half and moved underground, on two levels in the 7m-deep basement. The car park has been designed with future adaptation in mind. Access is via two car lifts – which means there are no ramps – floor-to-ceiling heights have been optimised, and soft spots have been considered in the design to enable reconfiguration into workspace.
The basement is in many ways the key to the development, stretching all way across the 1,300m2 site, to within 1m of a grade II-listed Georgian villa, Furness Lodge. The flexible-raft foundation, which requires just perimeter sheet piles, reduces the quantity of concrete in the substructure by about 270m3, or 25%. Extensive structural modelling indicated that the upward heave of the surrounding clay would remain within acceptable boundaries, with a 25mm swell projected for the centre of the site.
“That’s actually small- scale – we were comfortable with that,” says White. As there are very few case studies of this approach, Smith and Wallwork employed an independent geotechnical expert to conduct a peer review. “That gave us the confidence to go to the client and say, we can save you nearly 300m3 of concrete, simplify construction and make the dig easier.” Real-time remote sensors were installed on the surrounding buildings to monitor ground movements during construction.
The basement soffits reveal an intricate network of transfer structures, which carry the load from the superstructures down to the raft. “A bedroom grid doesn’t match a car park grid,” points out White. “The buildings all sit on different podiums and at different levels.” The basement soffits are a maze of drop slabs, beams that slant downwards mid-span, and cantilevers to the slab edge. Smith and Wallwork spent four months designing these structures alone to work out the most material- efficient solution: “Every beam is at 85-100% capacity.” The substructure includes 70% GGBS, so slower strength gain also had to be taken into account in the structural calculations. The architects have taken many of their cues from the historic college, parts of which date back to the 16th century. The Young’s Court facades echo the 17th-century Chapman’s Garden, with carefully selected red brick, in a narrow format, lent a handcrafted appearance through the use of churn-brushed lime mortar.
“Every facade responds differently to its context,” says Buckland, adding that they are more strongly articulated on the eastern elevations, which border a bustling side street and the green expanse of Parker’s Piece, one of central Cambridge’s largest parks. Hit-and-miss brickwork and setback upper floors soften the streetfront, while passers-by are offered glimpses into the landscaped courtyards beyond. Precast concrete lintels and cills evoke the limestone of the Front Court, and angled window reveals frame views out toward the park. In all, the facade comprises more than 300 precast units.
The overall Young’s Court development is part new-build, part reuse – an exercise in stitching together some of the more ad-hoc elements of the college. To the north of Young’s Court, Furness Lodge has been refurbished and extended on two sides, providing a double-height bar, common room and teaching spaces, as well as forming another courtyard. The 1960s student accommodation has been rejuvenated, with a gravelled courtyard flanked by plane trees. This is enclosed at its western end by a new, fully glazed cafe and informal workspace, which has opened up visual connections between Young’s Court and the historic Front Court and Chapman’s Gardens.