UK: Carrier has supplied centrifugal chillers delivering 16MW of cooling to 22 Bishopsgate, the new 62-storey landmark building in the City of London.
Also known as Twentytwo, the 912ft (278m) building provides 1,275,000ft2 (118,000m2) of residential, office and indoor amenity space. It is designed to achieve the highest standards of sustainability and occupant comfort, achieving a BREEAM rating of Excellent.
Its commercial tenants, along with 12,000 residents and visitors, numerous shops, restaurants, an auditorium, a fitness centre, and dedicated leisure and learning facilities are all air conditioned by four Carrier AquaEdge 19XRV high-efficiency centrifugal liquid chillers.
Installed by Michael J Lonsdale, each chiller delivers 4MW of cooling with efficiency levels as high as 6.8 EER. They are equipped with Carrier’s Greenspeed Intelligence variable speed drives to constantly match cooling output to the building’s heat load.
The high-performance chillers use a new high-efficiency dual-stage, aerodynamic impeller design, with tunnel diffusers based on aircraft engine technology. The compressor motor is cooled by refrigerant gas injection, further improving efficiency, while a patented float-valve system optimises sub-cooling and refrigerant level in the evaporator.
The chillers are controlled by a Carrier ChillerVu Plant System Manager (PSM) which connects with 22 Bishopgate’s BMS, providing high level oversight of cooling for the entire building, management and control of the chilled water system pumps, water quality control, and demand limiting and load shedding when the building is running on generator power. The PSM also provides the BMS with real-time operating conditions, including chilled and condenser water temperatures, chiller capacities and their status.
“Space was a key issue,” said James Snowball, Michael J Lonsdale’s project manager in charge of the air conditioning installation. “The building’s foundations and basement plant rooms were originally designed for a different project with a smaller overall floor space. This initial design was abandoned when the project was acquired by its current owners in favour of a new, larger building with a greater focus on occupant well-being. As a result, the building’s foundations were adapted, resulting in challenges to accommodate the building services plant required to support the larger building.”
James Snowball continued: “A solution from another manufacturer turned out to be too bulky to fit in the available space. Carrier’s 19XRV centrifugal chillers were proposed instead.”
The chillers are connected to evaporative cooling towers on level 58. A pressure break at level 25 effectively creates a lower and upper system, requiring careful balancing at the commissioning stage to optimise flow rates and ensure excellent performance while minimising energy use.
The four units were manufactured at Carrier’s chiller facility in Montluel, France. Due to their high capacity and size, one of the units was shipped to the US to carry out the customer witness tests at Carrier’s Charlotte, North Carolina facility.
Carrier also provided the equipment for cooling the building’s 54 lifts and associated motor-winding rooms.
The project developers were AXA IM – Real Assets and Lipton Rogers, with WSP as building services consultant.