Exploiting the value of multi-service chilled beams
Several landmark projects have demonstrated the potential of multi-service chilled beams, as we found from TERRY FARTHING and GUY HUTCHINS.It was back in 1996 that Trox first combined the function of a chilled beam with other services. Those multi-service chilled beams (MSCBs), as they have since become known, combined passive beams for cooling with lighting, sprinklers and passive infra-red control of the lighting. It was another two years before the next comparable job came along — for Lloyd’s Register of Shipping in London. That project was completed in 2000, and chilled-beam cooling was combined with lighting, sprinklers, pipework, cabling and controls. Terry Farthing, sales director with Trox UK, explains that the use of MSCBs for the Barclaycard building in Northampton in 1996 was prompted by the design team wanting a chilled-beam solution, having seen them used in Scandinavia. The Lloyd’s project was heavily architecturally driven, a demand that was readily accommodated by the extruded-aluminium construction of MSCBs. The success of these projects led to Trox promoting the concept heavily. ‘For the first time,’ says Terry Farthing, ‘we had to create a demand for something the market knew nothing about, and we had to educate them.’ Turning point
The next project arrived in 2001, for Airbus UK. Other projects include the GLA Building in London, the refurbishment and extension of the 30-year-old Riverside House in London and the refurbishment and extension of the Empress State Building in London. Those last two projects, believes Terry Farthing, marked a turning point in the acceptance of multi-service chilled beams and an increasing recognition of the value-engineering benefits of what could be regarded as the ultimate in the prefabrication of services in occupied areas. The level of interest is indicated by Guy Hutchins, product manager with Trox, having been involved in major presentations of MSCBs at the CIBSE conference for the last three years. Attractions
There are two major attractions of MSCBs. One is the ability for cooling and an increasing range of other services to be accommodated in a slab–to-soffit height of just 2.8 m. The other is the speed of installation on site, with associated significant reduction in programme time and resultant cost savings. The low height requirement has benefits for both new-build and refurbishment projects. If 700 mm is allowed for a ceiling void to accommodate services in a new building, the resulting slab-to-soffit height is 3.5 m. The simple arithmetic is that without a ceiling void, one extra floor in four can be built for a given building height. Refurbishment
The other, and to Guy Hutchins, more important benefit is for the refurbishment of buildings with a limited slab-to-soffit height. A prime example is the recent refurbishment of the 40 000 m2 Empress State Building in London to provide state-of-the-art office accommodation for the Landflex letting terms of Land Securities. Most of the floors have floor-to-soffit heights of around 2.8 m. That low height meant that the use of traditional air-conditioning systems with suspended ceilings would have resulted in very low floor-to-ceiling heights. Indeed, demolition may have been a preferred — about which John Anderson, the then development director with Land Securities, said, ‘Architects and engineers have successfully combined to recycle this low-height structure with an exposed soffit and multi-service chilled beams. To demolish and rebuild would have extended by programme by two years, with lost revenue in the order of £24 million.’ The beams for the Empress State building incorporate the following services. • cooling • fresh-air ventilation and maximum-humidity control • lighting and lighting-control modules • emergency lighting • PIR detectors • PA/VA speakers • service route for sprinkler distribution. Some floors have false ceilings and separate services, which required 16 weeks of installation work compared with just 12 week for those floors with MSCBs. The capital cost of the two approaches is the same. The comparison is the cost of fan-coil units, separate services and suspended ceiling with MSCBs and a concrete skin to enhance the appearance of the underside of the ceiling slab. Guy Hutchins summarises the principal benefits of MSCBs. • reduced building height • accelerated programme • earlier rent income • early capital repayment Bearing in mind that several weeks on site can be saved using an MSCB solution, substantial financial savings are immediately apparent. Aesthetics
The appearance of an MSCB can be readily changed simply — and quite cheaply. Guy Hutchins explains that the breakdown of costs is typically: • cooling, 50%; • lighting, 30%; • other services, 10%; • aesthetics; 10%. Investing a further 20% in aesthetics thus adds only 2% to the overall cost. A bespoke solution designed and built in factory conditions can also be tested in a room mock-up to ensure that air is delivered as required. The value-engineering aspects of MSCBs during the construction phase are complemented by the ease with which they can facilitate changes in layout — churn. Partition interfaces can be built in at, say, 3 m intervals, with infill sections to overcome acoustic problems and sound travelling from one side of a partition to another. Value-engineering benefits
From a slow start, the value-engineering benefits of MSCBs have played a key role in stimulating demand. Terry Farthing says that today they are Trox’s most popular system, and claims a 60% share of the market. Trox (UK) is at Caxton Way, Thetford, Norfolk, IP24 3SQ.