In order to achieve the Cambridgeshire NZEB brief, 80% of the building’s total energy demand (for everything) has to be met by its own power generation. This required a design which considered form, orientation, and envelope quality, to minimize energy demand and maximise PV outputs. The brief led to a strong focus within the design and build team on the building form, orientation and fabric performance, on efficient services systems and short service runs, tightly coordinated, and on the need to accommodate significant PV areas. These minimised demand and maximised generation.
At the same time as considering how to keep operational energy to a minimum, and provide most of its energy directly, we wished to minimize embodied carbon. Our experience of similar projects (using Oneclick LCA to calculate their embodied carbon emissions), demonstrated that emissions caused by the construction, maintenance and end-of-life of the building could often be significantly more than half of the lifecycle emissions. So with R G Carters support, vHH and Engenuiti, the structural and civil engineers, focused on minimizing the carbon intensity of frame and substructure and envelope, to target exceptional whole life carbon performance, without sacrificing any of the architectural quality. This led to the proposals being based on a lean mass-timber frame, minimizing plastic insulants and other plastic components, and with resilient and durable components and finishes. Much of the timber is expressed, bringing its advantageous character to everyone in the school.
Our design is made up of three areas; teaching wing, central block and pre-school, with carefully designed zoning for community use and spaces which can be adapted for different pedagogical layouts. Through extensive engagement with client and stakeholders we were able to propose a compact massing, with the halls at the centre of the plan and lit by northlight clerestory windows. The good form factor is combined with optimal orientation, with teaching space almost all facing north or south, and effectively shaded on the south, and with the facades of the School and Pre-school defining the small arrival plaza. Designed by Macgregor Smith, along with the rest of the school grounds, this creates an informal meeting place and the opportunity for small community events; an extension of Waterbeach woods, linking the school building to its surroundings and referencing the rural landscape beyond.