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Chilled Beam – The answer to everything?

It’s been said that one possible conclusion to the new Part L regulations is that chilled beams could take over from fan coils as the most popular ventilation system. Whether or not this proves to be the case, professionals take a closer look at this extremely versatile form of ventilation.

To measure IAQ, several factors are taken into account- noise, turbulence, changes in temperature, CO² levels (quality of fresh air) and ventilation efficiency. Failure to deal with any of the above criteria leads to lower levels of productivity and more complaints from staff. Therefore it is important to design a system that can deal with all of these issues. A chilled beam system is a commonly used air conditioning system that can overcome all of these problems.

A person sitting in the discharge path of, for example a split-system cassette or a fan coil unit can feel the air pass over them, as a typical discharge velocity is around 4 m/s. 

The discharge velocity from a chilled beam is typically 0.3 to 0.4 m/s which means velocities in the area that really counts, where people are sitting.

Changes In Air Temperature

The second advantage that a chilled beam system has over conventional systems is the discharge air temperature as not only is the air moving at a slower speed, it is a higher temperature as well. This means that air temperature difference within the room is typically only 2 or 3ºC as for conventional systems it is 7 or 8ºC.

Noise

The third major advantage for chilled beams concerns noise. As there are no moving parts and the air is moving at very slow speeds, there is nothing that can make noise! This is particularly true with a passive system, which recalculates.

What About The Employer

Research has shown that for every 1ºC above the optimum level (usually around 23ºC in the summer) there is a 5% fall in efficiency, so that is one considerable benefit of have an air-conditioned system. The chilled water is supplied at higher temperatures therefore the water chilled is now working as hard which means less electricity is used. So not only is the employer saving on running costs, he is also doing his bit for the environment by using less electricity.

Are the any disadvantages

Since chilled beams were introduced into the UK in the early nineties much has been learned about their limitations as well as their advantages but now that they are properly understood, it is fair to say most preconceived disadvantages can be designed out. The four common disadvantages are;

• Ensuring an unrestricted return air flow to the beam
• Condensation forming on the beams and dripping on to people, products and equipment below.
• Systems flexibility, i.e. Where an office experiences a change of use

The market for chilled beams has increased from zero to around £15m per annum depending upon how many large multi-function beam projects there are in any giving year. The huge advantages chilled beams offer, particularly in terms of running costs and comfort for the end user. With nearly twenty years of installed experience available the trend seems to be away from the more complicated, inflexible multi-function beam and towards standard induction and convection beams and in this trend, London seems to be leading the way.