Project leaders from SRA Architects, britplas, and Schüco discuss the collaborative processes and technical challenges behind the façade of the IMS-Tetsuya Nakamura Building in Oxford with AT’s Technical Editor John Ramshaw.
In association with
At the heart of most successful façade designs is a story of collaboration, teamwork and ingenuity. In this new technical series, sponsored by Schüco, we explore these important and revealing processes through a standout project submitted for the Schüco Excellence Awards. The sixth article in the series explores the IMS-Tetsuya Nakamura Building, which is home to the Institute of Developmental & Regenerative Medicine (IDRM) in Oxford. Completed in 2022, the 5,920-square-metre scheme was designed by SRA Architects for the University of Oxford, and delivered in collaboration with structural engineer Glanville, services engineers Hoare Lea, main contractor McLaughlin & Harvey, specialist façade contractor britplas, and façade, window, and door solutions provider Schüco.
Science and sustainability
The IDRM is located on the university’s Old Road Campus in Headington, a site dedicated to medical science research. Uniting existing research groups from across the city, the three-storey building provides a multidisciplinary and nurturing scientific environment aimed at developing treatments for degenerative age-related diseases, including heart disease, stroke, and primary immune deficiencies. Alongside state-of-the-art research facilities and specialist laboratories, the building includes a café, seminar room, and exhibition space, as well as informal break-out, meeting and discussion spaces organised around a triple-height atrium.
Aimed at creating a sense of openness and maximising views of the building’s parkland setting, the ground floor and atrium are fully glazed. The upper stories are clad in Corten steel, which is intended to evoke the auburn tones of nearby Victorian residential villas. In keeping with the university’s sustainability philosophy, the IDRM was designed to Passivhaus principles, including high levels of insulation and airtightness.
Schüco window and door solutions are central to the environmental and aesthetic performance of the façade, with FWS 50.SI (super insulated) and FWS 50.SI.SG (super insulated and structurally glazed) thermally-broken curtain walling used on the ground floor and atrium, and AWS 75 SI+ thermally broken windows employed on the first and second floors. The window systems are complemented by a glass brise soleil utilising Schüco bracketry, and ADS 75 SI thermally-broken doors.
Designing for Passivhaus
“The all-encompassing nature of Passivhaus meant it had to be considered holistically by the whole team, from the outset,” explains Matthew Slinn, project architect and associate at SRA Architects. “During the early design stages SRA worked closely with sustainability engineer Hoare Lea and Passivhaus assessor, Warm. Workshops were held to test the building’s orientation, form and glazing proportions. Passivhaus Planning Packages (PHPP), models and façade analysis were conducted to test the daylighting and energy performance of various glazing configurations. The analysis produced tangible results which could then be costed, enabling the client to make informed decisions on the fenestration design. Ultimately glazing was selected with a full-height vertical orientation which provided an optimal balance of daylighting performance and views out.”
Assembling the team
The project was tendered at RIBA Stage 3+ using a single-stage Design and Build contract. As the Employer’s Requirements (ERs) were based on a performance specification, it enabled early engagement with McLaughlin & Harvey’s supply chain to collaboratively develop the detailed technical design during RIBA Stage 4.
“Our approach was built on close collaboration with SRA Architects, Glanville, and McLaughlin & Harvey from the early design stages through to project completion,” recounts Andrew Harrison, britplas Design Leader. “This focused on adapting existing products wherever possible and engineering innovative buildable solutions when bespoke elements were required. We reviewed proposed solutions and worked through detailed interfaces to ensure the build met both the aesthetic and performance requirements.”
The focus on adaptation and innovation also necessitated a close working relationship between Britplas and Schüco. “We’ve enjoyed a partnership since delivering our first project together in 2017,” explains Schüco UK Business Development Manager Neil Hitchmough. “britplas engaged our Milton Keynes technical office to deliver this state-of-the-art research facility to Passivhaus design principles, while also maintaining architectural intent.”
Quality control
During the contract period, McLaughlin & Harvey operated a rigorous document management system, with strict review processes and approval workflows, ensuring details did not proceed to site unless full approvals had been sought. Physical sample panels were constructed within the first few weeks to agree key relationships and details. McLaughlin & Harvey hosted a series of airtightness workshops – attended by SRA, sustainability consultant QODA, Britplas, and M&E contractor Stothers – in order to review tricky details, and coordinate and reduce penetrations through the building envelope.
Making the grade: U-values
Achieving Passivhaus U-values had to be carefully balanced with buildability and budgetary constraints. “The Schüco façade systems were chosen for their superior performance and reliable test data, which pointed to their suitability in achieving the Passivhaus requirements for thermal performance and airtightness,” explains Harrison. “Specified with triple-glazing, the thermally-broken AWS 75 SI+ windows and FWS 50.SI and FWS 50.SI.SG curtain walling provided an overall projected U-value of 0.9 W/m²k.”
Solar gain and privacy were further design considerations in relation to the curtain walling and windows. “We used 300mm deep Schüco cover caps and a glass brise soleil to provide shading,” explains Harrison. These items, combined with triple-glazed, high-performance, solar-control window units, significantly reduce solar gain.” The glazing units also incorporate a bespoke frit, which was developed using a barcode pattern, and is intended to balance light transmission with visual privacy.
Making the grade: airtightness
In order to achieve the requisite level of airtightness, the building envelope was separated into five distinct zones: finishes, services, structure, insulation, and cladding. This not only simplified detailing, but also reduced potential thermal bridges. “Setting the position of the concrete frame and upstands with Glanville was an important piece of coordination early in the process,” recounts Slinn. “A composite stone wool sandwich panel system was used as a wall substrate spanning between floor slabs. This single product provided the weathertight, thermal and airtightness line for the majority of the building. The composite nature of the panel helped to reduce thermal bridging, as the outer sheet was strong enough to support the rainscreen cladding carrier system, avoiding the need for fixings to breach the insulation zone. It was also possible to install fenestration directly to the sandwich panels, which provided a robust and clean substrate on which to adhere the intermediary EPDM jointing membranes.”
The stringent airtightness requirements were made even more challenging due to the amount of mechanical and electrical equipment which had be ducted through the façade for the laboratories. Where possible, Schüco cable routing systems were used to reduce the number of penetrations through the curtain wall and help to attain the required air permeability performance. In addition, the team developed a bespoke removable mullion detail to allow plant equipment to be extracted without compromising the air and weathertight seals of the completed envelope.
Louvre and cladding integration
The façade’s glazed-in louvres provided a particular coordination challenge for the team spanning multiple disciplines. The louvres facilitate the connection of ductwork for the MVHR systems within the ceiling void above the offices and laboratories. “These are generally blanked off,” explains Slinn. “However, where ventilation is required a rectangular plenum box is sealed to the back of the louvre unit, onto which the 250mm ventilation duct is sealed, and all wrapped with insulation by the M&E contractor. This was a complex technical challenge which required the louvre blade free area to work with the airflow requirement of the ductwork – all within the constraints of the mullion spacing, and limited service zone above the ceiling. The proposals were achieved with a clear set of schedules, detail drawings and rigorous review process.”
The Corten cladding panels presented their own set of challenges, with potential staining and run-off a particular concern. Working closely with SRA Architects, britplas designed a series of interfaces between the steel cladding and aluminium windows and doors to avoid bi-metallic corrosion, as well as staining and run-off during the oxidisation process. “In some areas where contact could not be avoided, we pre-aged the Corten to ensure it would not ruin the Schüco curtain wall finish,” recounts Harrison.
Going above and beyond
The collaborative design and specification process not only resulted in a highly buildable and well detailed project, but also one that exceeded the stringent Passivhaus performance standards. “The curtain walling, including opening windows and doors, needed to achieve a projected overall weighted average U-Value of 0.9 W/m²K or better, explains Harrison.
“The actual value achieved was 0.76 W/m²k. Similarly, the air permeability target was 3m³/h/m²@50pa, and the actual value achieved was 1.86m³/h/m²@50pa.” Hitchmough echoes this point, “Assisted by Schüco commercial support, Britplas delivered a façade that went beyond the performance criteria required, but crucially remained within budget.”
Slinn is also justifiably proud of the project’s environmental achievements, which he says are “testament to the attention to detail and collaboration by all involved, from design stage through to expert workmanship on-site.” The architect also praises the role played by britplas in realising the original design intent. “They [britplas] understood the visual hierarchy envisaged between materials and the complex layering of the cladding and fenestration details,” he says. “Products were selected to meet the performance requirements and presented in a thorough manner, and physical sample panels were updated where required.”
