2nd March 2022

St Gabriel’s Primary School – Site Visit 01

vHH designed St Gabriel’s Church of England Primary for Urban&Civic (U&C) as a 3FE for phased delivery, with Phase 1 opening in 2017, but with planning permission granted for two further teaching blocks to provide additional forms of entry as required. Due to the robustness of house sales at Houlton, and increasing occupations, the second phase is under construction and due to open in Autumn 2022.

When we knew that the second block was required, at our suggestion, U&C commissioned vHH and Etude to undertake a simple post-occupancy study on the performance of Phase 1, to review what could be improved for the second phase. We found that whilst the teachers and pupils really liked their building, the natural ventilation strategy was not providing the air quality and comfort anticipated, and that energy bills were high. A key reason was that the teaching staff were too busy teaching to effectively control the natural ventilation openings in their rooms.

We set out to redesign Phase 2 to have significantly better comfort, operational energy use, and lower embodied carbon, but still complying with the planning consent. Etude reviewed the possibility of obtaining the Passivhaus standard, however the single storey block did not have the required form factor to make this viable. Instead, the building is designed to meet the AECB Standard, and will have mechanical ventilation with heat recovery, as well as opening vents for summertime free-cooling. It is entirely electrically powered, with VRV heating to each space. Instead of steel and concrete, the construction uses timber, with a cross laminated timber frame on a shallow raft foundation, significantly reducing embodied carbon and speeding construction on site.

Our first visit to site was scheduled during the under-slab insulation install, which aligned well with a workshop with ourselves, Etude and Lindum, the contractor, to run through how to achieve the required airtightness of 1 m3/hr/m2@50Pa. This included a handy presentation by Etude on the key elements to get right, and a discussion on sequencing to check that our details and the construction programme were aligned to achieve the teams’ aims. The completed Phase 1 can be seen in the background.