La Banque d'Angleterre rénove ses refroidisseurs d'eau

Un nouveau système de refroidissement installé dans les locaux de la Banque d'Angleterre, situés dans le quartier de la Cité de Londres, a fait économiser près de 48 % d'énergie de refroidissement, soit l'équivalent de 190.000 € par an.
A new cooling system at the Bank of England building, in the City of London, has saved an estimated 48% on cooling energy, which translates to €190,000 a year.

This project, implemented over two years, involved replacing three centrifugal chillers and two reciprocating chillers cooling the building with four new variable-speed chillers. The project also involved replacing six roof-top cooling towers – four for chilled water and two for the bank’s standby generators – and an 11kV/3.3kV electrical sub-station supplying the chillers.

The new water-cooled screw chiller, equipped with a variable-speed drive and hermetic motors, is able to adjust compressor speed in fine increments, optimizing operation for the conditions and load. It enables the chiller to match cooling output to building load precisely, thereby conserving energy. The unit supplies cooling for the building’s base load. It also has a built-in soft-start, ensuring low current draw and low noise upon start up.

Two of the other new chillers are also water-cooled units, based on twin-rotor screw compressors, providing additional cooling on top of the base load. The fourth, smaller chiller is used as the lead unit during the winter months. Heat is recovered from the chiller to supply the low temperature panel heating system throughout the building.
The design of the system was based on an N+1 redundancy approach towards the critical cooling load, including the bank’s data-center facility, which is considered to be of national importance.

The main challenge, however, was delivering the project while the building continued to function as normal, fully occupied, without any interruption of cooling to the building or its vital services. In this project, reducing energy costs and related carbon emissions were key drivers. A three-pronged approach to energy saving was used: a reduction in demand through improved design and building use; improved efficiency because of new and upgraded plant and equipment; and improved management through better monitoring and control.

The bank’s carbon emissions have been reduced by 717 tonnes of CO2 equivalent per year, representing an 8% reduction in overall emissions.