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UK’s 1st Passivhaus School: 14 times more airtight than standard new builds

It’s difficult not to be impressed by the Harris Academy Sutton in South London. Aside from the striking architecture, the building was designed to ensure pupils remain alert – which means classrooms that don’t get stuffy and have plenty of natural light.

But what really sets apart Harris Academy Sutton – the UK’s first ever Passivhaus school – is a level of energy consumption 80 percent lower than a regular new school building.

The sixth-form entry school, which accommodates 1,275 pupils and 95 staff, opened for the 2019/20 academic year and is part of Sutton’s plan to build a vast life-science campus for research, medical treatment, education and enterprise.

The role of air leakage testing

And as you might expect, air tightness played a critical role in ensuring super-low energy consumption. Indeed, the plans demanded that the school was 14 times more airtight than UK building regulations require. Air leakage tests had to be carried out on a continual basis, with every square inch of membrane undergoing thorough examination.

In particular, any type of drilling in the building envelope was strictly controlled.

Alongside an extremely airtight building envelope, the design required extra thick insulation in the walls, floors, and roof, and triple glazing in every single window and door.

Achieving Passivhaus in the UK

The Passivhaus building standard is less well known in the UK than in other parts of Europe – particularly Germany, where the standard originated, and Scandinavian countries. With this in mind there was a strong emphasis on sourcing building products of the highest quality – and ensuring that workmanship was carried out to the highest standard.

A ‘no blame’ culture was nurtured – encouraging everyone to speak up if they believed workmanship or products did not meet the standards of Passivhaus.

Air leakage testing services from Air Tightness Testing

Here at Air Tightness Testing our team has worked on a wide range of different projects, and understand the importance of meeting air leakage standards as quickly and efficiently as possible. iATS-registered and UKAS-recognised, we use industry standard tests to pinpoint air leaks, then work to find a solution – so a property can be placed on the sale/rental markets, or in the case of schools and other public buildings, open its doors on-time.

iATS Registered and UKAS Recognised


We are registered with iATS (Independent AirTightness Testing Scheme) and use equipment calibrated by UKAS laboratories. Our testing procedures are also recognised by UKAS.