16/10/2023

Exemplar Passivhaus Projects in the Higher Education Sector: Cambridge Study Trip Two

As part of an ongoing CPD programme of presentations and research into Passivhaus in the HE Sector, we visited two completed Passivhaus projects.  Both recent developments by King’s College, Cambridge.

King’s College benefits from an impressive stock of buildings built over the past six centuries, which includes some of the most celebrated buildings in Cambridge, but in order to meet the proposed year-on-year growth of circa 6% in student numbers, the College needs to expand its student accommodation.

The Cranmer Road graduate campus by Allies & Morrison is the College’s first major Passivhaus project in Cambridge and comprises of two distinct, new buildings – a ‘Garden Building’ and a ‘Villa Building’ set within the gardens of three existing villas.

The second project by Feilden Clegg Bradley Studio (FCBS) at Stephen Taylor Court provides comfortable homes for graduates, fellows and their families and is set within landscaped gardens along a crescent shaped inner street.  It also re-purposes an historic villa as common room and library.

Our hosts for the day were Shane Alexander the King’s College PM and Gwilym Still the Passivhaus lead at Max Fordham. Plan A are currently working with Gwilym on the LSE Firoz Lalji Global Hub, 35 Lincoln’s Inn Fields.

Key takeaways from the study visit include:

  • The two projects showcase many of the approaches to sustainable and low energy design that are essential for designers aspiring to achieve net zero carbon.
  • Both are new graduate campuses are within sensitive Conservation Areas, successfully adopting a contextual architectural language that met planning restrictions.
  • Wellbeing has been considered with high quality landscaping that has been sensitively designed to respond to immediate surroundings
  • Both projects are ultra-low energy, all electric, Passivhaus developments that deliver operational excellence.
  • The projects have been constructed to an exacting high standard with airtightness results that are better than the Passivhaus limit and considerably better than building regulations allow
  • The summer comfort strategy has a combination of automatic bypass of the heat exchanger on the mechanical ventilation units, and openable windows.
  • At Stephen Talyor Court, energy strategy includes the use of ground source heat pumps and a heat exchanger to provide low-energy cooling in summer and heating in winter.
  • The buildings utilised CLT construction to deliver a low embodied carbon structure and an air/water tight envelope before the outer masonry walls were constructed.
  • The detailed design of the building envelope is fundamental to delivering Passivhaus, and both projects have been carefully designed to maintain continuity in the insulation and limit cold bridging within the building envelope.
  • The workmanship of the building contractor is key to delivering the envelope design in line with the Passivhaus exacting standards. Choosing the right main contractor is important.
  • The student rooms incorporate sensors to ensure the room temperatures and ventilation are optimised to maintain the low operational energy performance even if the students try to over-ride the room controls.
  • Both projects demonstrated that quality can be achieved via different procurement routes, one being D&B, the other traditional.
  • Clear governance, communication channels, and well managed stakeholder engagement made for efficient decision making.
Projects Practice