Winner: Harris Academy Sutton

Entered by Wilmott Dixon / Architype

Willmott Dixon worked with Architype and Sutton council to deliver an efficient and innovative secondary school in the south London borough; the UK’s largest built to Passivhaus standard. Key to the design standard is removing complexity; despite its large scale, Harris Academy Sutton is heated by just one domestic boiler for 1,250 students. Low and zero carbon technologies were chosen to efficiently lower demand for electricity, with photovoltaic roof tiles contributing 10% of the school’s energy generation.

A partnership of client, contractor and architect meant shared goals around delivery were achieved. Sutton council wanted an innovative new science specialist school to sit as a gateway for the new London Cancer Hub, a world-leading medical research and treatment site. Willmott Dixon invested in training with its supply chain partners to attain the Passivhaus standard. A mock-up classroom was constructed before work on site began, to help tradespeople know how to achieve excellent airtightness, and airtightness champions were appointed, resulting in a remarkable score of 0.3ach – twice the Passivhaus required standard.

Architype worked with educationalists to ensure the school functioned to the latest pedagogical thinking. For example, the flexible science classrooms accommodate 60 students to reflect the school’s focus on science excellence. Students are taught about sustainability while inhabiting a space that demonstrates a low-carbon future in its very fabric. The north/south-orientated design facilitates Passivhaus implementation by optimising solar gains in winter to minimise heating demand, and brise-soleil is used to mitigate any overheating during the rest of the year, when the sun is higher.  

End-user experience was a central factor in the design, with environmental sensors being placed in each room to help maximise electricity conservation by telling students and teachers when it would be best to open or close windows. Teachers at Harris Academy have since commented on how the students remain alert at the end of a long day and behaviour is improved thanks to the stable and clean air quality.

Harris Academy Sutton exceeds standard performance in a number of ways. Its gas and electricity usage to date represents a saving of 59% against CIBSE Guide F good practice secondary school measures and saves 72% against TM46 benchmarking.

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