Project Capella is an £80m 18,000m2 biomedical research laboratory for the University of Cambridge (UoC). Located within the Cambridge Biomedical Campus, £600m of research buildings are being constructed concurrently.
As a research facility, the building must meet strict environmental and vibration criteria. The latter is typically met via an insitu concrete frame. Collaborating early with PCE, our offsite superstructure specialist, we aimed to prefabricate as much of the superstructure as practically possible. The result is unique, a hybrid of precast and insitu concrete being used in a bio-science environment where vibration control was the primary driver for superstructure selection.
80% of the frame and façade was built off-site as high quality precast modules. Six upper floors comprise precast columns, edge beams and precast floor slabs with an insitu structural topping. Stability cores comprise volumetric precast sections with precast stairs installed on site.
Our approach has ultimately reduced the programme, allowing construction to start earlier. Project Capella was transformed from blank piece of paper to an enclosed building in 24 months.
Arranged over six storeys above a basement, the superstructure is principally configured from precast concrete elements, columns, stability cores, shear walls, stairs, landings and the lower portion of the floor plate. Edge beams are precast concrete to simplify interfaces with the façade whilst efficiently controlling deflection limits, spine beams are a shallow composite steel/concrete beam to keep beams supports to the same depth of the floor slab. PCE has been able to optimise structural efficiency, internal finish and simplify construction. This coupled with the integration of reconstructed stone façade with integrated glazing has created the perfect balance of quality, cost and programme.
The strategic decision to utilise prefabrication throughout Project Capella was made early in the design process. Kier's appointment during RIBA Stage 1 meant that we were able to lead and influence design decisions early, resulting in a shift from traditional construction methods towards maximised prefabrication. A precast solution for the frame was not an obvious choice for a biosafe laboratory where vibration control is a primary driver. Insitu concrete frames have historically been the method chosen to achieve vibration requirements.
The use of precast concrete was driven by a multitude of factors including the University of Cambridge's (UoC) requirement to fund the project across financial years; prefabrication enabled them to spend money earlier. Extensive ongoing construction projects in the Cambridge market resulted in pressure on available resources (labour and concrete supply) for the onsite delivery of concrete frames. In addition Cambridge is a city where vehicular access is second to bicycles. Therefore reducing the number of deliveries and vehicle movements to and from a site is a key factor in successful programme management.
Offsite prefabrication of concrete units provided commercial benefits to the project through improved programme along with the difference in labour rates between the fabrication facilities and Cambridge. By reducing the overall programme the project also realised benefits from reduced levels of inflation.
The use of pre-fabricated concrete elements enabled the project to consistently achieve the enhanced levels of finish required for the exposed concrete. It enabled decision making to be brought forward in the programme. This was key to the project's success where there are a large number of end users and engaged stakeholders linked to the project.
Preglazed precast façade panels lead to the building being watertight significantly earlier which is key in a laboratory building, enabling early MEP installation when compared with traditional construction methods.
For your chance to learn more about offsite construction in the healthcare sector, Explore Offsite Healthcare will be presenting a range of projects on 20 September at the NEC in Birmingham, for more information or to book your place please visit www.exploreoffsite.co.uk.
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