Royal Papworth, one of the world’s leading cardiothoracic hospitals and the UK's main heart and lung transplant centre, recently located to a new purpose-built site at Cambridge Biomedical Campus. Set in landscaped grounds, the 40,000 square-metre hospital has two large atriums, 310 beds, six operating theatres, extensive diagnostic and test facilities, a 46-bed critical care unit, plus a restaurant, coffee shop and convenience store on the ground floor.
Additional cooling was required to support the hospital’s energy centre to ensure optimum conditions were maintained throughout the building during peak times. The turnkey project for main contractor Skanska included the supply of four high-performance chillers, remote power generators, crane lift equipment, scaffolding and pipework insulation.
At the heart of the site’s energy centre is a large tank that acts as a thermal store, based on 20% glycol in water. Carrier Rental Systems supplied four Carrier AquaSnap 30RB402 air-cooled liquid chillers running on R410A refrigerant, operating in two pairs configured in series. Bespoke manifolds were created to make connection easier and ensure greater control.
The chillers, positioned on the roof, are powered by two SLD diesel generators, each supplying 500kVA of remote power. Due to the close proximity to the hospital, acoustic attenuation barriers are used around the chillers and generators to acoustically seal them and ensure low noise for patients and staff.
Plant control and integration were important aspects of the project. Flow meters and temperature sensors were installed at key points in the cooling circuit to improve control and optimise performance. Skanska connected the chillers to the site’s Building Management System, giving fine high-level control of units and enabling them to operate with maximum efficiency alongside existing plant.
“The thermal storage tank provides a thermodynamic buffer to meet cooling needs across the site,” explained Marc White, Carrier Rental Systems director and general manager. “The additional chillers augment capacity to ensure there is sufficient headroom at all times, irrespective of load or weather. It provides complete reassurance that whatever the conditions, the critical work of the hospital can continue uninterrupted.”
Work on site was carried out on a Sunday to maintain access to the hospital’s busy goods loading area. Carrier Rental Systems was additionally responsible for fuel management to ensure continuity of power generation throughout the project.
“We worked closely with the CRS team to design the auxiliary cooling system and ensure it would integrate with the site’s existing plant to maintain required conditions. It was delivered according to the brief, and has operated very effectively since being commissioned,” said Sean Smith, senior project manager with contractor Skanska UK.