The University of Oxford’s dreaming spires are more ecologically sound in their slumber thanks to a £43 million student-housing development comprised of three new Passivhaus buildings and the low-carbon retrofit of a grand Victorian villa for St Edmund Hall.
The world’s oldest surviving academic society for housing and educating undergraduates, St Edmund Hall appointed London-based architect Wright & Wright (which recently completed an award-winning renovation project at Lambeth Palace) to increase capacity at Norham Gardens from 56 to 127 bedrooms, at the same time as boosting sustainability.
This means that the college (alumni include Sir Keir Starmer and Monty Python’s Terry Jones), which is targeting net-zero energy use by 2030, can now house every undergraduate in affordable, purpose-designed living spaces, allowing private rental accommodation to return to the local market. Norham Gardens, a tree-lined residential road that runs alongside the northern edge of University Parks, is part of the North Oxford Victorian Suburb Conservation Area (NOVSCA), an Arts-and-Crafts district that was one of the UK’s first conservation areas back in 1968.
The three new buildings, which incorporate traditional local characteristics, such as gables, chimneys, dormers and ornamental ironwork, were built in full adherence to Passivhaus standards (see 'What is Passivhaus?' below), with the effect of reducing operational energy demand by up to 70% compared with standard new-build benchmarks.
The retrofit — of an 1874 villa designed by local Gothic Revivalist architect Frederick Codd — used breathable natural materials, including wood-fibre insulation, cork and lime-based insulating plaster, as well as biosolar roofs and conservation-appropriate glazing, in accordance with Passivhaus’s guiding principles.
Together with the creation of new gardens and outdoor common rooms — involving the planting of rare and climate-resilient trees and wildflowers — the project has delivered an 88% biodiversity net gain. ‘It’s a great win for all. Even the local wildlife has benefited. We’ve put in log stacks and installed swift and bat boxes in the brick façades,’ Ronan Morris, a partner at Wright & Wright, tells Country Life. He adds that the project offers lessons for owners of all kinds of historic buildings, and not only those occupied by collegians and chiropterans (bats), in retrofitting their own homes to be more sustainable, as well as preserving charm and character.
‘With historical homes, the traditional problems are being leaky and losing heat quickly, but when you try to rectify that, you can create unintended consequences,' adds Morris.
'For instance, if you don’t insulate correctly, you risk trapping moisture within the walls, so you need to go about it the right way and that means understanding what it’s made from. Is it stone? Is it brick? Which way is the house orientated? Are you getting a lot of wind-driven rain on one side? You may need to consult a specialist conservation architect, but there is a lot of good retrofit guidance available from organisations such as Historic England and the Passivhaus Trust.’
Morris also advises looking at the roof — one of the main areas of heat-loss — with insulation here helping to reduce bills. ‘Then come the windows and doors and there are lots of great, historically appropriate products out there, including triple glazing, which are coming onto the market now,’ he continues.
‘The industry is finally catching up with the idea that, to meet our climate targets, we’re going to need to build in other ways, and that’s going to require a different approach to historic properties, too. Buildings are living, breathing things, not merely historical artefacts, and we have to make them fit for people and the planet.’
What is Passivhaus?
Passivhaus is an international low-energy, high-comfort building standard that originated in Germany. Designed to deliver exceptional energy efficiency, comfort and durability, the first concept house was completed in Darmstadt in 1991 and there have since been tens of thousands of Passivhaus-certified homes registered throughout the world. Its UK affiliate, the Passivhaus Trust, has set itself a target of 10% of all new homes in the UK being built to Passivhaus standard within the next 10 years.
Spokesperson Chayley Collis says: ‘The building physics behind Passivhaus apply to any building, whether new-build or retrofit. With an existing building, you can’t change the building’s orientation, structure, shape or amount of glazing. The Passivhaus standard, therefore, includes a retrofit standard called EnerPHit that takes these limitations into account and relaxes some criteria to reflect this.
However, it is still a very demanding standard and will typically result in a building that out-performs a new-build property, both in terms of energy and comfort.’ Passivhaus projects must adhere to key principles that include high-performance windows and insulation, an air-tight layer to minimise heat loss and efficient mechanical ventilation with heat recovery (MVHR).