St Catherine’s College, Ainsworth Centre, Oxford
The new Ainsworth Graduate Centre is a striking circular design yet one that sits harmoniously in a location steeped in history. The building resides on the site of the original Grade I listed campus designed by renowned architect Arne Jacobsen.
Built between 1960 and 1964, Jacobsen designed the college’s main campus in its entirety. Since Jacobsen’s death in 1971 additional buildings have been delivered by the Danish architect’s assistant, Knud Holscher, and Stirling Prize-winning RIBA past president Stephen Hodder. Architects Purcell designed the new Graduate Centre as a continuation of the second phase of Hodder’s development by following his typology as sensitively as possible.
Proteus HR TECU bronze cladding panels were specified for the cylindrical three-storey hub, which features a seminar room and common room, as a reference to Jacobsen’s use of the material on previous projects at the college, synchronising old with new.
Proteus HR is a modular rainscreen system that offers a smooth façade with recessed joints. The panels have a lightweight aluminium honeycomb core structurally bonded between two thin gauges of metal. The lightweight nature of this rainscreen system minimises weight loadings on the underlying structure whilst achieving strength and rigidity.
The panels are fixed onto a unique system of aluminium carriers and ancillary components, which were designed and manufactured by Proteus Facades. Proteus fabricated the structural element of the fixing system so that it physically curves around the building. Installers Norman & Underwood then secured the flat panels to create a faceted façade that, when viewed from afar gives the perception that it is curved around a tight radius.
Proteus Facades also fabricated three varieties of TECU bronze fins for external use on glazed sections. Shorter fins were secured with a modified vertical aluminium extrusion cloaked with TECU bronze and secured with stainless steel brackets. Each one is fixed off the curtain wall system, with the TECU bronze capping designed bespoke to achieve the maximum depth from the glazing line to create a more striking aesthetic.
Deeper, vertical TECU Bronze fins are secured to a bespoke structural frame up to 450mm off the cladding line, which compartmentalises the façade. The vertical fins frame the structural bay and are fixed off curtain walling, spigoted into the ground and bracketed at the head. The internal aluminium carcass was secured with structural brackets back to the curtain wall and plated at join positions with discrete fixings.
Horizontal beams on the top of the upper level were fabricated in a curve and fixed to a bespoke aluminium structure, then cloaked with the TECU Bronze material from Proteus. Norman & Underwood secured the beams with structural gusseted brackets fixed back to the primary structure. All three types of fins went through a double-marquette process, where principal and secondary designs were presented to the architects and client for review before manufacture.
As well as a reference to the original campus buildings, the bronze finish of the panels and fins was specified to contrast in tone and glossiness with stainless steel panels, also manufactured by Proteus Facades, which feature on existing and the newly developed student accommodation blocks adjacent to the centre.
In the early 1990s and 2000s Hodder added three accommodation blocks to the site, housing a total of 54 rooms. The facades on these buildings feature Proteus HR Stainless Steel cladding panels, manufactured by Proteus Façades several decades ago. This material was originally chosen as the smooth finish of the stainless steel stands out against the coarse finish of the concrete structure creating a textured facade.
Like the Graduate Centre, the newest student accommodation pavilions are a continuation of Hodder’s development, adding 78 large spacious en-suite rooms connected by glazed stairwells. The façades of the new buildings imitates those constructed by Hodder, and so Proteus Facades was appointed to fabricate exact replicas of the original Stainless Steel panels they manufactured some twenty years previous for the new development, whilst using more modern methods of construction.
The stainless steel panels sit inboard of the building’s concrete frame with a standard pattern of two panels adjacent to large rectangular windows on each of the rooms. The Proteus HR rainscreen panels were supplied pre-finished with a 240S brushed polished finish.
The aluminium carrier system used is fully adjustable on all axis, allowing exacting sightlines to be maintained across the façade. This enables the façade at St Catherine’s college to make the most of linear shadow lines between the Proteus HR panels and concrete structure.