Zero Carbon London
→ UK’s first net zero carbon school
→ Designed to ‘PassivHaus Plus’ standard
→ Bio-based and recycled materials
→ Renewable energy onsite to provide 100% annual demand
Hackbridge is a new build primary school for 210 pupils aged five-eleven (and expandable to 420) and nursey provision, built next to the pioneering BedZED One Planet Living development. It is the UK’s first true net zero carbon school (regulated and unregulated), and aims to be the first to be ‘PassivHaus Plus’ certified, pending final sign-off.
To achieve net zero carbon the design applies rigorous PassivHaus building envelope insulation and air tightness requirements, with triple glazed windows that enhance thermal comfort and provide excellent daylighting. Modelling was carried out to ensure the orientation of the building was optimised for solar gains, reducing the risk of overheating and minimising cooling requirements.
Essential to the success of this project was the commitment to net zero by all stakeholders. Therefore, careful consideration was taken by the architects and engineers, to select materials that enhance health and wellbeing, have low embodied energy and be easy to construct and maintain. This included the use of significant amounts bio-based and recycled materials.
A highly efficient ground source heat pump system with inter-seasonal heat storage meets space heating demands and majority of domestic hot water demands. To meet summer peaks and provide resiliency against climate change the system also has a parallel heat exchanger to enable free cooling to be extracted from the ground. By extracting free cooling from the bore holes during the summer this enables more efficient operation of the GSHP during winter and reduces energy demand overall.
The building relies on a central air handling unit to distribute fresh air throughout the occupied rooms. The air is transferred from the occupied rooms to the main hall and WC rooms for extraction. This allows the overall volume of fresh air to be optimised and allows heat to be recovered from the whole building. Occupied rooms operate on a mixed mode basis so that the use of natural ventilation is encouraged when external temperatures are moderate.
A rooftop PV array positioned over a biodiverse roof has been designed to provide renewable electricity to offset 100 per cent annual demand.