Air conditioning Fan coils/chilled beams
T
he fan coil unit is a well-established terminal system for controlling room temperatures and comfort. But it has a rival in the form of the chilled beam, and the two systems have been
vying with each other for specifiers’ attention for a number of years. But comparison between the two is complicated by
the fact that a fan coil unit has a single function, while chilled beams can be integrated with other building services to create multi-service chilled beams. According to Mike Beeton, business development
manager for systems at Halton Products: ‘If chilled beams were superior in every way, they would have completely replaced fan coils in new-build projects by now.’ He says that one of the main drivers of chilled
beams’ growth in popularity is the changing legislative and cultural environment. He says: ‘New regulations promoting energy efficiency – such as Approved Documents L2A, governing conservation of fuel and power – are leading to greater demand for water-based cooling. Such systems need less energy to provide the cooling requirement than cooling through the air.’ He
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believes another major factor in the shifting market is the gradual disappearance of inaccurate preconceptions about chilled beams, chiefly concerning cost and flexibility. ‘While acknowledging their popularity elsewhere
and generally accepting their low running costs, UK specifiers had considered chilled beam systems as expensive to install. This meant that the capital cost had deterred specification of chilled beams for “normal” projects. ‘They had tended to be considered only for such
major clients as banks and blue-chip companies, despite offering a lower lifecycle cost than four-pipe fan coils and other alternative systems.’ These perceptions have arisen, he claims, because
of the way in which systems had been specified. But growing emphasis on carbon and energy is now forcing people to think beyond lowest cost first and to consider operatoinal performance and energy use. ‘Designers of such spaces as open-plan offices have tended to minimise costs by opting for 4 to 6kW fan coil units. To supply an equivalent cooling load would normally require three or four chilled beams for
Chilled beams were installed in the London headquarters of the National Audit office
> July 2010 CIBSE Journal 47
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