Carrier Delivers Chiller Retrofit for Citi's London Headquarters
Carrier Air Conditioning provide UK Chillers, Bms System, heating controllers and aircon units

Carrier has delivered substantial savings in carbon emissions and building operating costs for Citi, following a chiller upgrade project at the group’s London headquarters.

To meet the customer’s requirements for increased energy efficiency, Carrier upgraded two Carrier AquaEdge™ 19XR5 centrifugal chillers with variable speed drives based on Greenspeed® intelligence, enabling a significant reduction in operating costs.

Carrier designed and built a custom solution matched to the exact requirements of the project. This solution helps reduce chiller energy consumption by adjusting cooling capacity to match the building’s load in real time.

Based on an initial analysis carried out by the Carrier engineering team, the energy saving potential for both chillers upgraded with Greenspeed® intelligence was estimated at £126,000 per year. Power use was then monitored before and after the installation. During the first three months of operation, the results showed actual savings of £33,966, exceeding anticipated savings.

With Carrier’s variable speed drive system, end users can reduce energy use and cut their carbon emissions, as well as extend the working life of chillers. An added benefit is lower servicing costs, as the soft start and soft stop routines contribute to less wear and tear on the system.

A further benefit is a substantial reduction in noise, due to the modulation of compressor running speed. The Carrier system also helps deliver highly stable comfort conditions, as chiller output is closely matched to load, producing a more comfortable and productive environment for building occupants.

The project was carried out in two stages. The first involved installing Greenspeed® intelligence on the first centrifugal chiller. The reduction in energy consumption as a result of the upgrade enabled Carrier to make a supported case for upgrading the second centrifugal chiller, which was accepted by the client.

During the installation phase, due to height limitations in the building’s basement plant room, Carrier co-ordinated the dismantling of the large variable speed drives before they were moved in three sections, and their re-assembly once in position in the plant room.

“The key aim of the project was to reduce energy use without affecting comfort conditions inside the building, in order to lower building operational costs and associated carbon emissions,” said Paul Clements, UK engineering asset manager, Citigroup Realty Services. “We worked closely with Carrier throughout the project to ensure the requirements were met. As the figures for chiller energy consumption demonstrate, the project has proved to be highly successful and met its objectives.”

As a result of the project’s success, Carrier has secured subsequent orders for several Greenspeed® intelligence upgrade projects on centrifugal chillers serving multi-storey commercial buildings in London and elsewhere in the UK.

For more information, contact Graham Easter on Tel 01372 220 220, email

Read the full case study here or download the case study PDF below.

Case Study – Office Building Solutions

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