Passivhaus Affiliate

Full marks for Lucy Cavendish Passivhaus!

PHT members R H Partnership Architects (rhp) have just graduated as Passivhaus architects with a sustainable new development for Lucy Cavendish College in Cambridge.  The recently completed mixed-use project, set in West Cambridge's historic conservation area, combining student accommodation, social spaces and a café.


Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge


Complementing the surrounding College buildings and the character of the site, the building is a part three-storey, part four-storey structure with a café and study space on the ground floor.  The newly completed building is an exciting achievement for Lucy Cavendish College and the project team, setting a new benchmark for energy use and inclusive design as part of the College’s vision for the future.


Professor Dame Madeleine Atkins, president, Lucy Cavendish College, University of Cambridge


To meet the College's ambitious near zero carbon future-proofing visions for the future, an ultra low energy (& carbon) design was crucial.  To minimise the embodied carbon within the building, the primary structural design utilises CLT (Cross Laminated Timber) and low embodied carbon cement replacements.  The CLT primary structure also forms the airtightness line, with taped panel joints and robust detailing achieving a final air test result of 0.3 ACH, well within the Passivhaus target of 0.6 ACH.


Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge


Sympathetic to the existing buildings in the conservation area, exterior hand-made tile hung façade ontimber framing together with lime mortar brickwork help reduce the embodied carbon by up to 30%,reducing the volume of material used and balancing embodied carbon with longevity and materials thatcan, ultimately, be recycled at the end of the building’s life. These areas of façade are tied back to the mainstructure using glass reinforced polymer (GRP) brackets – an innovative approach to reduce the heat lossusually associated with steel ties.


Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge


  Key Stats:

  • Construction: Cross laminated timber and low embodied carbon cement.
  • TFA:  2965 m2 
  • Number of student rooms: 72
  • Build start date: June 2021
  • Completed: August 2022
  • Certified: Passivhaus, 2022
Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge

Building Performance:

The certified Passivhaus scheme means low energy in use and high comfort with design energy targets in line with industry carbon-zero frameworks from the RIBA, LETI and the UKGBC.  The design eliminates the use of fossil fuels, with 100% of the electricity supplied by renewables.

Image credit: rhp sustainability statement


Beyond the building fabric, the carefully considered landscapes integrated drainage strategy will help to reduce and control water run-off whilst providing irrigation to landscaping.

Designed energy performance:

Heating (≤15kWh/m².yr)

14 kWh/m².yr

Cooling (frequency of overheating >25°C: 10%)     


Airtightness (≤0.6ACH @50pascals)

0.3ACH @50pascals

Renewable primary energy (≤60kWh/m².yr)

58 kWh/m².yr

Annual CO2 emissions (kgCO2eq/m2)  

24.3 kgCO2eq/m2

Heating, ventilation & hot water:

The all-electric building minimises impact by using efficient MVHR and ASHP equipment for ventilation, space heating and hot water.  The innovative foundation details, developed by Smith and Wallwork structural engineers with input from design team, then delivered by SDC and their team, minimise the connection from the foundation to the ground floor and therefore reduce heat loss through the ground, while timber brise soleil and projecting details provide solar shading and maximise views out to college gardens.

Image credits: © R H Partnership Architect & © Smith and Wallwork


   Overall U-values*:   

  • Wall: 0.133 W/m²K

  • Roof: 0.141 W/m²K

  • Floor: 0.205 W/m²K

  • Windows (uninstalled): 0.81 W/m²    

  • Doors (uninstalled): 0.9 W/m²K 

Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge
* area weighted


Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge


  Key Team:

Lucy Cavendish Cambridge | Image Credit: Nick Gutteridge


The first certified Passivhaus project for architect rhp and main contractor SDC was officially handed over to the College in August 2022, after just 80 weeks of on site work.  In December 2022, the Passivhaus Institut certification plaque was installed after the building achieved Passivhaus Certification in early October.  


Quote | Tom Foggin, Director and Architect, rhp

Interested in Passivhaus education buildings? Discover more student accommodation projects here.


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Further information

Lucy's new student accommodation

Lucy Cavendish College: sustainability statement

Passivhaus for educational buildings

How to build a Passivhaus webinar series: March - June 2023

RIBA Passivhaus overlay

Passivhaus benefits guide

Passivhaus certification

Passivhaus for educational buildings

Previous PHT Story: Cambridge becoming Passivhaus student digs hotspot - 25th January 2021

Architect's Journal: rhp completes Passivhaus student accommodation for Cambridge college - 23rd January 2023

SDC: SDCs first Passivhaus project - 20th October 2022

2nd March 2023

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