Tell us about the early design brief
The legacy of London 2012 is intended to benefit both homeowners in the new residential blocks and the wider Leyton area. Our client, Lend Lease, placed Chobham Academy at the heart of a new community that features sustainable, high-quality construction alongside a range of amenities.
What challenges did you face along the way?
The new 15,300m² school, which incorporates three separate buildings, is due to open in 2013 with places for 2,000 children aged between 3 to 18. Working within criteria set for the entire Olympic site simplified some procedures, but planning restrictions also imposed site-wide constraints that directly affected the design.
What about specific design challenges?
The site was previously used to produce concrete for the Channel Tunnel, so prior to demolition the ground was littered with services and residual concrete. The majority was removed in time for construction, but some services remained and were carefully considered in our foundation design.
Due to these uncertain ground conditions, piling was a contractual stipulation and under the circular Main Building this included sections of bridging over a disused water main. An earth tube system incorporated as part of the sustainable ventilation strategy that ran in large pipes under areas of landscaping also required sensitive handling in the foundation design.
In terms of structure, the buildings were kept as simple and flexible as possible. We reviewed various options including steel, concrete and timber to establish the most efficient material. We adopted a concrete frame construction across all three buildings to allow consistent use of the same contractor in achieving the ‘urban’ aesthetic envisaged by the architect, with timber glulam roof beams to the atrium of the main building and the specialism building.
In terms of sustainability considerations, good thermal mass will reduce heating and cooling mechanisms in the future and we also used GGBS (Ground Granulated Blast furnace Slag) in the concrete mix, which reduced the cement content by up to 36%.