The inverter-driven screw chillers were selected for their exceptional energy efficiency, reliability, environmental performance, low noise, reduced running and servicing costs, and the high quality indoor climate they provide for building occupants.

Built in 1723, the five-star hotel located in Grosvenor Square has 308 rooms, including two Presidential Suites and an Executive Club Lounge overlooking Grosvenor Square. The building has a colourful and unique position in English history as the place that the Duke of Wellington’s defeat of Napoleon was announced in 1815.

The Carrier AquaForce Vision chillers replaced two ageing chillers by another manufacturer that had reached the end of their working life, and were proving increasingly inefficient and unreliable. Carrier's Modernisation Team carried out the work on a full turnkey basis, managing all logistics associated with dismantling and removing the old machines and replacing them with the new Carrier chillers.

Challenges included limited space on the building’s rooftop to accommodate the new machines, and strict controls on noise levels due to the hotel’s high standards for guests and surrounding residential properties. There were also limitations on power which meant careful assessment of start-up and peak loads were required.

John Lam, who headed the Carrier Modernisation team on the project, said: “The customer was also keen to minimise capital costs and maximise return on investment in a package that could be demonstrated to reduce the building’s carbon footprint. All in all, it was a pretty challenging brief. However, due to the AquaForce Vision’s excellent energy performance and proven underlying design and engineering, we were able to meet the requirements and deliver for the client.”

Two Carrier AquaForce Vision chillers – with a combined cooling capacity of 1460kW – were installed within the limited 6.8m foot-print available. The work included installation of integrated hydronic modules linked to the chiller's variable speed drives, chiller sequencing control and factory-fitted remote monitoring.

An energy usage simulation produced by Carrier highlighted that the building has a peak cooling load of 1400kW and a base load of 700kW, requiring the chillers to operate an average of 18 hours a day throughout the week. Using Carrier’s Chiller System Optimiser software program, the team calculated that the new installation would consume 20 percent less electrical power than the previous chillers, delivering savings of 345,079 kWh of electricity, equating to an annual carbon saving of 179 tonnes of CO2.

Pranavan Natiala, Millennium Hotels and Resorts regional director of engineering and projects – Europe, said: “We required a best-in-class solution for this flagship UK hotel. Energy efficiency, part-load performance and low noise – all within a compact footprint – were critical. It became clear during the tender process that Carrier’s AquaForce Vision range provided the best solution. The quality of this product, proven reliability of the Carrier brand, plus the technical expertise and support offered by the Carrier Modernisation Team, were the reasons we chose Carrier.”