The Stephen A. Schwarzman Centre for the Humanities at the University of Oxford will mark a number of firsts.

This ambitious 23,000 sqm project will be the first of the University’s buildings to so purposefully integrate state-of-the-art academic teaching facilities and publicly accessible performance and exhibition spaces. Designed to be inclusive and welcoming to students, staff and public alike, it will mark a milestone in community engagement.

Located in the centre of Oxford opposite the Grade I listed Radcliffe Observatory, the Centre will bring together under one roof seven faculties, two institutes and six Bodleian libraries, a 500 seat concert hall and three other performance venues, exhibition and film spaces.

The Schwarzman Centre will also be the University’s first major Passivhaus project, and is on track to be the largest Passivhaus certified building in the UK, setting a new benchmark in sustainable, energy-efficient facilities. In addition, the project will be the first in the world to contain a concert hall, successfully applying Passivhaus standards to a uniquely complex building with interfaces between public, private and performance functions and ventilation strategies.

Although Oxford City Council planners require new buildings to use the BREEAM certification, the University have made a case for Passivhaus as their key metric, preferring its focus on low energy use and therefore low running costs. For some time, they have used design guidelines which required all buildings to be ‘designed to Passivhaus standards’ but have upscaled their ambition for the Schwarzman Center, which will be the first major project to actually target certification.

The challenges of achieving certification on such a large and functional building are significant, so in order to reduce risk and manage costs, Laing O’Rourke (LOR) worked closely with the University on a year-long PCSA (Pre-Construction Service Agreement) to establish the viability of the aims, during which Stage 4 designs were developed in close collaboration with the client, design team and specialist contractors. The Passivhaus Institute were then invited to assess the project’s likelihood of achieving certification, which gave the team to proceed with confidence.

Passivhaus requires heating demand of less than 15kWh/m2/yr, air permeability of less than 0.6m3/m2/hr @50Pa and targets energy consumption of less than 70kWh/m2/yr. It achieves this through exceptional levels of insulation and airtightness, utilising air source heat pumps and all-electric power. As architects, it was essential that we had the contractor’s buy-in to the designs and the very high levels of workmanship required to achieve this, as well as a clear understanding of the contractor’s intended installation sequence, in order to detail the various elements such that these high standards could be met.

We developed designs for the external envelope alongside LOR’s supply chain - a number of whom were experienced in off-site prefabrication - which included prefabricated stone and brick faced precast cladding panels, handset stone with SFS backing, large format Passivhaus certified triple glazing and a glass dome.

Large scale mockups were constructed and tested to obtain invaluable information about buildability. We had to adjust our detailing of windows fitted to the rear of brickfaced precast cladding panels for example, once we realised that the ‘wobbliness’ of the handmade bricks was making it impossible to achieve the required seals at the originally intended dimensions.

We worked with LOR and Passivhaus consultant Etude on minimising thermal breaks and detailing that would help with buildability. Materials were chosen as much for buildability as performance – a foil faced ductwork insulation commonly used externally as duct lagging was chosen as the inner layer of external wall insulation as it had an integral vapour control layer (VCL) which gave a readymade airtightness line. Black butyl tape (rather than silver) was chosen to seal these insulation sheets, so that it could be visible, readily inspected and signed off as part of ongoing workmanship protocols, which also included a programme of hold points for inspections, benchmarking of standards to help inform the workforce, and sequential air tests, from which lessons were learnt and processes improved.

A collaborative approach and excellent communication between all parties at every step of the design and construction, has been essential to the success of this ambitious process, managing out risk and surprises.

The project was the subject of a masterclass at this year’s Passivhaus Trust Conference with presentations by the University of Oxford, Laing O’Rourke, Hopkins, sustainability consultants Max Fordham and Etude, and the Passivhaus Institute.

Read more about the project here