The Passivhaus Trust commends the innovative Spencer Building at Corpus Christi College, University of Oxford

Gold-standard extension for world-class collection

An Oxford college library extension and special collections centre targeting Passivhaus aims to increase space, improve access, and safeguard a world-class collection while minimising the building's operational energy use. The Spencer Building is an ambitious new build project with historic façade retention, designed within a constrained conservation site in line with Corpus Christi College future development plans.

Founded in the 16th century, the library at Corpus Christi College is of national architectural and historical significance, However, it has been challenged by limited space and not meeting the current needs of students and staff. The Spencer Building will Increase the number of study spaces, improve disabled access, and create a fit-for-purpose specialist archival store. It extends and redevelops the library, while respecting the heritage of the site within the Oriel Square Conservation Area.

The design has been developed to simplify the form as far as possible to minimise surface area heat loss and simplify insulation details. There are two different zones within the building which are thermally seperated to avoid heat gains, and dealt with separately for Passivhaus Certification:

- The archival stores.
- The occupied spaces.

Across three floors, the new reading rooms have been designed to ensure that desks are in the brightest part of the plan, overlooking the garden quad. This reduces the need for artificial lighting and provides excellent views.

Construction

The Spencer Building retains medieval fabric on three elevations and is built on top of historic foundations. New ashlar sandstone cladding was used for other elevations. Incorporating high levels of insulation has increased the depth of the walls and roof on an already tight site. In addition, the airtightness boundary was carefully considered to ensure the hygroscopic historic stone walls avoided unwanted build up of moisture. The project was managed carefully throughout the design process and the details discussed & agreed with the Passivhaus certifier.

Maintaining existing medieval stonework on some elevations significantly reduced embodied carbon, but resulted in some complex detailing to meet Passivhaus requirements.