Carrier chillers feature in BREEAM ‘Outstanding’ refurbishment for PwC
Carrier has supplied three high-performance screw chillers for the refurbishment of PwC’s headquarters at 1 Embankment Place in London, helping achieve what is believed to be the highest-ever BREEAM rating for new-build and existing buildings — 96 out of a possible 100, a rating of ‘Outstanding.’
The building-services solution for the 42 000 m2 commercial office building was designed by ChapmanBDSP. It is based on a biofuel-powered CCHP (combined cooling, heating and power) plant. Cooling is supplied by three Carrier AquaEdge 1.4 MW water-cooled inverter screw chillers and adsorption units by another manufacturer.
The Carrier chillers are equipped with Greenspeed intelligence and have an SEER in excess of 10.0. Water cooling, rather than air cooling, enables a much higher capacity to be achieved for a given external-plant footprint and is inherently more efficient.
To provide resilience, the chillers are sized so that two machines can meet the anticipated load, enabling one machine to remain on standby. They also provide full back-up in case the CCHP plant has to be taken offline for maintenance.
Chilled water cools the building via chilled beams. Boilers provide heating to augment the low-grade hot-water circuit from the CCHP systems. High-quality comfort conditions are supported throughout the building with a combination of air-handling units and fan-coil units.
The compressors in these chillers are based on a tri-rotor screw design (pictured), rather than a conventional twin rotor. The benefit is a much more balanced compression process, enabling tighter tolerances to be maintained. Other benefits are lower parasitic losses and better overall efficiency.