Castle Bailey Quad delivers a 54-bedroom student accommodation development that meets the Passivhaus Institute's Low Energy Building (LEB) standard while sensitively complementing the college's historic 13th-century architecture.
The project for St Peter's College, addresses a pressing challenge facing Oxford colleges: providing affordable student accommodation in a city where soaring private rental costs create significant barriers for students from lower-income backgrounds.
Given the site's unique constraints, the LEB standard was selected over Passivhaus Classic to allow greater design flexibility. This was essential for a site constrained by archaeological sensitivities and planning restrictions, which ruled out technologies like ground source heat pumps and visible solar panels.
Despite these limitations, the project represents a significant achievement in sustainable construction. St Peter's is one of the first student accommodation developments of its kind in the UK, achieving exceptional performance metrics compared to typical UK new buildings, and receiving Passivhaus LEB certification from WARM in 2025.
The development achieves LEB airtightness levels of 1.0 m³/m²/hr - compared to around 51.0 m³/m²/hr for a typical new building - and space heating demand of 30 kWh/m²/yr - compared to over 50 kWh/m²/yr. Overall, the completed project achieves a 43.8% carbon reduction over the baseline design—surpassing Oxford City Council’s Local Plan 2036 target of 40%.
A ‘fabric first’ approach was central to the design, using high-performance insulation, continuous thermal insulation, and triple glazing to minimise heat loss. Careful attention to thermal bridging throughout the design process ensured exceptional airtightness levels.
Energy efficiency was further enhanced through LED lighting with occupancy and daylight sensors, real-time energy monitoring, and mechanical ventilation with heat recovery.
A standout innovation was the Waste Water Heat Recovery (WWHR) system, which captures heat from shower wastewater to pre-warm incoming cold water. This technology reduces hot water demand by 35% while requiring minimal maintenance and no visible external equipment. The use of water-saving fixtures also met Oxford’s residential water efficiency target of 110 litres per person per day, showing how the project looked to broader sustainability goals beyond energy and carbon.
Professor Judith Buchanan, Master of the college, said:
"St Peter’s is a beautiful college, but it is compact. Being able to offer more accommodation for our students matters crucially. Oxford’s private rental market is extremely expensive in ways that hit the poorest hardest.
“This eco-friendly new development enabled us to extend our accommodation offer to undergraduates in ways that are economically so important for them, while making a transformative difference to the feel of our whole estate."
St Peter's College student accommodation represents a landmark achievement in sustainable construction, proving that low energy buildings can be successfully delivered on challenging heritage sites while meeting the practical needs of educational institutions.
