TROX VAV FAN COILS SAVE ENERGY IN BROADGATE TOWER
25/01/2008
Leading air distribution system provider TROX UK has supplied a complete package of fan coils and diffusers for two BritishLand projects in London, one of which is currently the tallest building under construction in the city.
The fan coil units incorporate EC motors which have the advantage of infinitely variable speed. These variable air volume fan coil units (VAV/FCU) can provide significant energy savings compared to the standard constant speed units which have been around for the last 40 years. For example if the air volume was reduced to, say, 80% of maximum (i.e. a 20% reduction in air volume) the electrical power consumed by the motor would be halved. If the air volume was reduced to, say, 60% of maximum the electrical power consumption would be reduced to less than a quarter.
The 165m tall BroadgateTower skyscraper is being built in conjunction with its neighbour – the 63m high 201 Bishopsgate – and the two buildings will be connected by a glass canopy.
TROX has two separate orders for the shell and core work at both speculative office block projects, which are being constructed in tandem.
The order for the grilles, diffusers and fan coil package on BroadgateTower came from FCS Ductwork and the order for 201 Bishopsgate was from Gardner & Co (Kent) Ltd. On both buildings the consultant is JB & B and the construction manager is Bovis Lend Lease.
The fan coil units supplied are waterside fan coils with ultra high efficiency and low energy electrically commutated motors – the first TROX UK has supplied on a significant site. The motors have infinitely variable control on a 0-10V signal.
TROX conducted energy efficiency testing and a full control mock up test on that job with extensive test reports to the design team.
Says Neil Addison, TROX UK’s Southern area sales manager, “The efficiency testing was done with BritishLand present at our factory in Thetford. We then did noise testing at the Sound Research Laboratories and made did further mock ups at Thetford. Finally, we did a controls mock-up at Thetford where the commissioning company, the controls company, the consulting engineer, and Bovis and the contractors attended. This was a high end engineering solution thoroughly tested.”
One significant challenge TROX faced and overcame was how to ensure the highly efficient EC motors integrated with the BMS. As Mr Addison explains: “We needed to make sure the signals within the 0-10V banding gave the correct voltages to achieve design duties and turn down.
“Where you have a variable air volume fan coil as opposed to a fixed volume, you also have to take into account the grille and diffuser selection so that the grilles will still perform their air distribution function even when the air is turned down. There is a limit to how far the air flow can be reduced because around about 60% of maximum air flow the diffusers will dump. Furthermore when the air volume is increased the air flow has to be much higher, up to 80%, to re-establish the air running across the ceiling. As air distribution engineers, TROX are ideally placed with their extensive test facilities to ensure that the diffusers are sized so that optimum air distribution is achieved.”
When completed, the 35-storey BroadgateTower will be the seventh highest building in London and the third tallest in the City. Along with the adjoining 201 Bishopsgate, it will contain more than 850,000 sq ft. Construction of the tower is scheduled to be finished in May 2008 with its smaller 10-storey neighbour programmed for completion in February 2008.
