Principles and Benefits of Chilled Ceilings

Static cooling systems (chilled ceilings) have, over the past 40 years, proven themselves capable of delivering high levels of occupancy comfort at reduced running costs. Frenger designed, supplied and installed the "World's Largest Radiant Chilled Ceiling" system in 1962; the 175,000 square meter, 27 stories high, Shell Oil headquarters, situated on the river Thames in London. This building was also the first fully sealed air conditioned building in Europe and was revolutionary at its time as this Chilled Ceiling used the River Thames water to cool the building down. This was achieved by pumping in cool water from upstream to a secondary heat exchanger which in turn cooled (took heat out of the building by "Radiant" absorption) the building down, then depositing the warmer return water from the secondary heat exchanger downstream. This installation is still operating after nearly 50 years and is a testament to the integrity of the product and to Frenger's design capabilities.

Since this time the cooling requirements for a typical office environment have increased considerably; improved insulation, higher occupancy densities and a much higher usage of IT equipment have all fueled this increase. It became apparent in the mid 1990's that the cooling capacity of a traditional chilled ceiling was not sufficient to meet these increased heat-gains, and consequently higher-capacity passive chilled beam fin coil batteries were introduced into perimeter zones to offset the solar load generated at the building façade.

Although fin coil batteries provided the extra cooling at lower cost in £ / watt than the radiant ceiling, the perimeter aesthetics suffered due to the fin coil batteries requiring large size perforations and percentage open area to allow air ("convection") to circulate and this also reduced occupancy comfort, due to higher air velocities.

Frenger however saw the opportunity to take all the benefits from a traditional chilled ceiling for radiant cooling, and to develop a "hybrid" product solution that also has the cooling performance of passive beams coupled with "Radiant cooling" to yield the same aesthetics as associated with the traditional Radiant Chilled Ceilings and in turn low air velocities for compliance to ISO 7730 European Standard for "Indoor Air Comfort Conditions" given that Frenger's "hybrid" chilled beams have a 35% to 40% "Radiant" quotient.

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