Air conditioning features thermal wheels

Paul Boughton

Fläkt Woods is providing the ventilation system for The Walbrook scheme, the £155 million design and construct, office and retail development between Bank and Cannon Street stations in London.

The Walbrook is a designed by Foster and Partners and is being built speculatively. Located near Canon Street, the scheme will incorporate Flakt Woods’s largest ever air conditioning systems, the colossal EU 84’s, which will provide the ventilation for the 42,000 m2 of office and retail space.

Commisioned specially for the project, the EUs are connected to the building management system and as well as being large, each contain a unique configuration, making interconnectivy with other services easier. They also feature exceptional noise deadening characteristics.

Every unit incorporates Flakt Woods’ patented thermal wheel, the most efficient method of energy recovery. They will recover up to 90 per cent (typically 75 to 85 per cent) of the energy in the extract air. Another major benefit is that they are only 500 mm in length irrespective of size required.

For example, a thermal wheel with an efficiency of 76 per cent reduces the annual heat demand by around 95 per cent. The 76 per cent is derived from the energy recovered at peak load. At any other moment the amount recovered increases until, at a certain condition, the energy-recovery device supplies all heating required. (in this instance, the heating system needs to be on for 1100 h a year as opposed to 2300 h for the run-around coil with an efficiency of 42 per cent). These calculations are based on Flakt Woods Acon Software for AHUs with an electricity cost of 6p/kWh.

Similar to many buildings, the exterior of The Walbrook will be encased with solar shading which will help keep the building cool in the summer and warm in the winter, thus improving energy efficiency. But the cladding on this development is entirely comprised of a Fiber-Reinforced Polymer (FRP) with an automotive finish – making the sheen resemble that of a car. Main construction work on the 10-storey site has started and completion is scheduled for late 2009.

Skanska's team on the project includes Foster & Partners (architect), Arup (engineer) and Roger Preston and Partners (M&E design).

Work is expected to begin this summer, to complete the project by the end of 2009 making a high-tech 50 metre long impact along Cannon Street.

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