Cambridge refurb project to be the deepest shade of green

The Entopia Building, a retrofitted 1930s Telephone Exchange at 1 Regent Street in Cambridge, will be transformed over the next 10 months into an ultra-low carbon headquarters for the University of Cambridge Institute for Sustainability Leadership (CISL).

CISL intends to use this project as a case study to show others how they too can show ‘sustainability leadership’.

The showcase retrofit is projected to result in an 80% saving in whole life carbon emissions compared to a standard office refurbishment. It will be carried out according to EnerPHit, the Passivhaus standard for refurbishment and one of the most stringent standards for energy retrofits. It will deliver 75% lower heating demand in comparison to an average office building, and airtightness at more than five times that required by building regulations.

It is also using second-hand light bulbs and second-hand furniture to maximise its green credentials.

The £12.8m retrofit has been supported by a £6m donation from greentech leaders Envision Group and a £3m grant from the European Regional Development fund (ERDF), which is also funding the operation of a sustainability hub and small business and start up accelerator for three years. The University has invested its own funds in the project alongside an internal grant from its internal Energy & Carbon Reduction Project.

ISG chief executive Paul Cossell said: “The significance of this project cannot be underestimated in the wider context of the UK achieving its 2050 net zero emissions target. With the built environment contributing around 40% of the UK’s total carbon footprint, this ground-breaking project is a pioneering case study on the smart transformation of an existing building, prioritising sustainability criteria as core drivers for every single element of the retrofit.

“We confidently expect the new design modelling, material and methodology innovations at the new CISL headquarters to provide the springboard for greater collaboration at an industry and client level to fast-track the reduction of carbon emissions from our built assets.”

The Entopia Building aims to earn all the badges going, including BREEAM Outstanding and Well Gold as well as Passivhaus Enerphit.

Alexander Reeve, sustainable building advisor in the University of Cambridge estates division, said: “The project is a very exciting pathfinder project for the university estate, as we refine our strategy to eliminate fossil natural gas as a fuel for our many older buildings. It demonstrates that there is a way to transition to low carbon heating whilst conserving Cambridge’s outstanding built heritage.

“Through the project we have been able to demonstrate the viability of measures such as internal wall insulation and triple glazing which have significantly reduced the size of the air source heat pump installation and avoided the need to upgrade electrical substation capacity. This means the only significant external alterations are the glazing and a solar power photovoltaic array on the roof.

“The investment in building fabric is expected to increase the long-term value of the building, with an energy performance certificate of ‘E’ expected to become an ‘A’, lower utility bills, and lower plant maintenance costs.”

Wendy Bishop, associate & Passivhaus designer at Architype, the project architect, said: “The Entopia Building aims to show building owners what can be achieved with a clear focus on cutting operational, embodied and whole life carbon in existing buildings, while creating beautiful and healthy places to work. The project balances the technical demands of meeting the EnerPHit standard with the sensitivities of dealing with a building in a conservation area. Focussing on internal finishes and using bio-based materials that met the multiple certification requirements, as well as using Architype’s pioneering ECCOlab embodied cost and carbon software, we were able to radically reduce embodied carbon and enhance air quality.”

BDP is building services consultant on the project. James Hepburn, principal at BDP, described it as “the most significant project of its type in the country – proving that the most sustainable building is one that already exists”.

He added: “The measures we are incorporating go far beyond standard sustainable buildings and the integrated and collaborative approach to design, operation and management from all stakeholders will undoubtedly result in a truly efficient, world class facility.”

University vice-chancellor Stephen Toope said: “The Entopia Building will become the most sustainable premises in the University of Cambridge Estate, marking a major contribution to our world-leading target to eliminate our emissions and putting the wellbeing of its occupants – and wider society – at its heart.”

The Entopia Building aims to open to staff by the end of 2021.

Got a story? Email news@theconstructionindex.co.uk