Case study Office new-build
in using 80% recycled aggregate in the building’s concrete structure for the first time – an achievement that merited the award of the first-ever BREEAM point for Innovation. On the office floors, the enhancements included
the replacement of the office fan coil units with active chilled beams. The amount of fresh air supplied to these units is minimised by linking it to CO2 concentration in the offices.
Make sure the support of your
developer, contractors and design team matches the vision of your clients – Bob Spittle
In another brave move, the building’s electric
perimeter heating was replaced by a low-grade hot water heating system fed from heat recovery units added to the building’s roof-mounted chillers. The units supply low-grade hot water at 45 deg C, but the addition of the heat recovery system also improved the chillers’ efficiency by 35% and earned the design team another BREEAM point for Innovation. In addition, a sophisticated control system was also
developed with extensive sub-metering to monitor cooling, heating, power and lighting loads on a zone- by-zone basis. The offices are also fitted with an ultra-efficient,
high-frequency, fully-programmable low-energy lighting system, which is daylight-linked. The system uses internet protocol, which enables it to be controlled
by the building’s occupants via their PCs within strict boundary conditions and will incorporate time-clock control and presence detection for out-of-hours working. In hospitality areas, restaurant, cafes and corridors, BDP has opted for high-efficiency LED bulbs to help reduce maintenance and save energy. The building has even been future-proofed to allow
further environmental enhancements when these become cost effective. This includes strengthening the building’s structure in key areas to enable the tenant to install rainwater storage tanks in the future. There is also provision for the future installation of a solar electric array on the building’s roof – should it become cost effective for PwC to do so. Having achieved BREEAM Outstanding for the
design, the next challenge for the designers is to work with the contractors to ensure the construction waste targets are met and the scheme achieves an Outstanding rating under the BREEAM post-construction review. ‘We’re not being complacent; we’re working hard with the contractors to ensure that they meet these very challenging targets,’ says Runicles. The good news for the design team was that
the building succeeded in achieving a BREEAM Outstanding rating based on its design. It was also awarded an energy performance certificate A rating. According to Runicles, the building will achieve ‘a 70% improvement in CO2 emissions over current (2006) Approved Documents L2A’. The good news for the tenant is the integration of the developer and tenant teams, meaning the estimated cost increase of taking the building from BREEAM Excellent to BREEAM Outstanding was limited to £2.50 per sq ft. l
Fact file 7 More London’s high-performance features
• Argon-filled, low-transmission glazing building envelope, based on an argon-filled, low transmission glazing system, fitted with extensive shading to minimise solar heat gains
• Specification of the CHP engines enhanced to enable them to run on any biofuel, including used cooking oil
• Biofuel-based tri-generation system to produce heat, power and cooling using absorption chillers (CCHP)
• Plate heat exchangers added to CCHP units to increase the use of waste heat and extend the CCHP unit’s run time to provide up to 25% of the building’s total electricity demand
• Solar thermal hot water supply to the core’s toilet pods and a heat recovery ventilation system
• Replacement of the office fan coil units with active chilled beams
• Low-grade hot water heating system, fed from heat recovery units, added to the building’s roof- mounted chillers
• Sub-metering to monitor cooling, heating, power and lighting loads on a zone-by-zone basis
• High-frequency, fully-programmable low-energy lighting system, which is daylight-linked. Fitting of LED bulbs
• 80% recycled aggregate used in the building’s concrete structure
• Regenerative braking system incorporated into the building’s 16 lifts
The key to attaining the Outstanding rating was to start with a good base building – Stephen Runicles
www.cibsejournal.com July 2010 CIBSE Journal 29
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