Oxford’s first class Passivhaus project

The pace of construction is largely due to the contractor’s offsite construction methodology. The rapid programme is even more remarkable considering the Schwarzman Centre, when finished this summer, will be the largest ever Passivhaus-certified building in the UK, though it may soon be overtaken by student accommodation building 2 Trafalgar Way in London Docklands, if it gains certification on completion.

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Stephen A Schwarzman Centre for the Humanities

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With its Rutland limestone and handmade brick cladding, the Schwarzman Centre looks at home next door to the Grade I-listed Radcliffe Observatory, constructed for the university in the late 1700s in an altogether more labour-intensive way.

Built on the site of the former Radcliffe Infirmary, the new humanities building will bring together nine faculties and institutes onto one site, plus seven libraries and collections. Arranged around a central atrium beneath a glass dome, the Schwarzman Centre has four storeys above ground and a two-storey secant-piled basement below.

The ground floor will be home to a cafe, exhibition hall, the Bate Collection of Musical Instruments and a 100-seat cinema. The upper floors will have teaching, research and study areas and the main library. Below ground, a double-height foyer provides access to a 500-seat concert hall, the 250-seat humanities lecture theatre, performance space and a recital hall.

A £185m donation from Stephen A Schwarzman, CEO and co-founder of investment firm Blackstone, has made the creation of this building possible. The total cost of the project is higher than this and remains confidential.

Passivhaus record

Achieving a Passivhaus-certified building was not part of the contract with Laing O’Rourke, explains Jennifer Makkreel, project director and deputy head of capital projects at University of Oxford: “Laing O’Rourke was contracted to deliver the targets which would achieve certification. We didn’t want to tie ourselves in a knot because of certification.”

Instead, the approach was to embed Passivhaus principles into the design philosophy, checking at each stage of development whether certification would still be achievable – given the demands of the project brief, budget and delivery timescale.

“It is a value-driven approach to certification more than a contractual approach,” says Makkreel. “A big part of that is having the right culture between ourselves and sharing the same values in what we want to achieve.”

Although the university has a capital works framework for projects over £20m, the humanities building was such a specialist major project that it warranted its own tender process, says Makkreel: “We did a very extensive procurement exercise, a longlisting which included our framework partners, then shortlisting, and then short-shortlisting.”

With two contractors in the final running, a key consideration was who the main contractor would bring with them as key supply chain partners. “We wanted to make sure that we were able to hit the ground running on the pre-construction services agreement (PCSA), with the right people in place to help to develop the design,” says Makkreel.

Laing O’Rourke, of course, can offer a unique proposition when it comes to supply chain, with so many specialist contractors within its group. On this project, Expanded delivered the piling and the precast concrete structure, Crown House Technologies delivered the mechanical and electrical works, and Vetter the facade, with the panels manufactured off site in Laing O’Rourke’s Nottinghamshire facility.

Designing a building for Passivhaus and designing for offsite manufacture have a lot of synergies in terms of planning, with digital having a crucial role, according to Holland.

“We want to build the building twice,” he explains. “First, we do a digital build to work out all the complexities, issues, problems and challenges. That gives us the confidence to go and do it physically.”

There are 204 federated models that feed into that digital build. As the various models are federated, a digital script checks that updates or changes haven’t created problems such as clashes or unachievable tolerances.

“Instead of needing lots and lots of human checks, and the risk of human error or something being missed, that can all be automated with the digital script,” explains Holland.

Although the team hit the ground running, the PCSA was a few months longer than it might have been, had the plan been to deliver the building traditionally. However, that investment in time upfront has paid dividends in terms of achieving the overall project programme and quality goals, says Makkreel.

Developing the details

Out on site, Holland points out some of the details developed during that PCSA period. For instance, a band of granite around the base of the building was added after the team took a walking tour of Oxford to look at stonework details which did – and didn’t – work on the city’s many historic buildings. The granite band will stop water soaking up into the limestone.

The precast facade panels, delivered with windows already installed, are stacked one on top of the other, tied into the building’s concrete frame rather than hanging from it. “That reduces the load on the structure and reduces the cost of the structure,” says Holland.

Another important detail developed during the PCSA means that there are no visible vertical joints at all in the facade – something that the architect and client were keen to avoid. Instead, the facing stones or bricks on adjacent panels were designed to interlock with each other.

“That enables a monolithic finish of the stone,” says Holland.

It is impossible to see where the precast panels meet the small section of hand-laid stones which form the arches to the entrance.

Inside, there are several ‘wow’ moments. The first comes on entering the atrium area on the ground floor – the Great Hall – which is lit from above by the glass dome, which has an intricate timber framed dome below it. This space will be open to the public, often used as a cafe, sometimes an event space or even a dining room.

The architectural competition which resulted in the winning design by Hopkins resulted in three different proposed layouts for the building, says Makkreel. One was a street, the other had a courtyard, and then this one with the atrium.

“We had to think about Passivhaus in considering what form of building would work best,” says Makkreel. “Both the street and the courtyard had a lot of facade. This design brings light into the centre of the building while having a relatively regular form to help with Passivhaus principles.”

The design of the dome took up a lot of time during the PCSA period, with supplier Novum brought in early. Both the glass and timber elements arrived on site as a kit of parts, to be assembled at ground level and craned into place.

One major change was to simplify the dome so that it will not be providing ventilation or smoke extraction functions. “We simplified it so that the dome is just a dome,” says Holland. “We put the mechanical ventilation next to the dome instead of in those rectangular voids at the corners of the atrium. That gave better value for the client.”

On the three upper floors, graduate students will be able to study, looking over the balcony. Some of the beautiful oak cladding and furniture around the atrium and on the upper floors has already been installed. Meanwhile plasterboard, flooring and other fit-out work is underway alongside M&E works.

Heading downstairs from the atrium, the timber-clad four-storey concert hall is already breathtaking.  Holland explains how James Johnson built the elements in its Dagenham factory to be lifted through the ceiling and assembled, paying credit to section manager Jack Higgins who devised a temporary suspended floor, to be hung off permanent fixing points, avoiding the need for a birdcage scaffold for the work at height.

This hall has been designed by Arup Acoustics to have world-class acoustics. “Achieving that with Passivhaus was extremely challenging,” says Makkreel, going on to explain how its low-energy, incredibly quiet air-handling unit will be the first of its kind.

To help meet its Passivhaus credentials, the building will be heated by air source heat pumps, with solar panels on its roof providing some of its electricity. It is also connected to an energy centre, built at the same time as the Andrew Wiles Building next door, which has ground source heat pumps which can top up the humanities building if needed.

Making history

The Schwarzman Centre will be the second University of Oxford building to achieve the Passivhaus certification, following the Student Hub for Kellogg College, completed in 2017.

By the time students, staff and members of the public walk into the humanities building in September 2025, it will look like it has always stood there, with paving, lawns, gardens and trees linking it to the buildings that surround it.

However, the story of its heroic build will not be forgotten. Historian Professor William Whyte, who is the project sponsor, is producing a book about the construction delivery.