Multi service chilled beams address the sustainable issues and are one of the most energy efficient terminal air conditioning systems.  Terry Farthing, Head of Communications of TROX UK examines these feature and comments on the increasing popularity of this system.

Independent research organisation BSRIA estimates that the market for chilled beams grew by 33 per cent in 2006 compared with 2005 and predicted further growth of 40 per cent for last year.  However the all embracing term chilled beam includes, of course, the MSCB which in value terms is between 2 to 5 times greater than that of a commodity beam.  As such the great surge in market value reported by BSRIA has been heavily influenced by the popularity of the MSCBs.  Indeed, over the last five years, they have really come of age, with leading developers such as Land Securities and Stanhope acknowledging their benefits and starting to install them on increasingly large and prestigious projects including speculative office developments.   There are, in fact, a wide range of good reasons for the enthusiastic approval with which MSCBs are now being greeted.

One of the most important is related to their superb energy efficiency performance.  MSCBs are the most energy efficient terminal air conditioning system and compared to constant speed AC fan coils the saving in carbon emissions is around 15%.  This in itself is a compelling reason to utilise this new air conditioning system.  However there are many other features which are making this system so popular.

Sustainability is becoming another major influence in the selection of air conditioning systems.  With MSCB the chilled water temperatures are elevated at 14ºC flow and 17ºC return.  This means that renewables such as ground water can be more effectively utilised.  Also with sustainability you have the life of the building and system to consider.  Most pre 1970 office buildings have a low floor slab to soffit height. Traditional comfort cooling solutions require a false ceiling which reduces this height too much. Hence, landlords tend to opt for expensive new build to ensure a modern office environment and sufficient space for the increased cabling and other services.   However, MSCBs solve the space problem because they can be fitted directly to the soffit and be left exposed, meaning that there is no need for a false ceiling. This, in turn, means that the slab to soffit height is sufficient, even in refurbished buildings.  TROX, for example, has supplied MSCBs successfully down to 2.8m high which allows 100mm false floor and no false ceiling.   So MSCBs offer the opportunity to modernise and recycle older buildings – a more sustainable solution that also costs less and is available quicker.

With the MSCBs there are no moving parts, no fans, no filters, and as such the life of the unit is much longer than with a traditional air conditioning system.    Typically fan coils have a life of 15-20 years, whereas with MSCBs it is in excess of 30 years.  Product or system life is an important and often overlooked factor in the sustainability argument.

As mentioned above, with exposed MSCBs there is no need to have a false ceiling.  Most false ceilings in modern office buildings are hiding an array of cables, pipes, ducting, etc., which can now be incorporated into an architecturally designed raft.  Anyone looking above a false ceiling would be amazed at the untidiness and dust and dirt that are allowed to accumulate above sophisticated machines and people who need a clean, controlled working environment.

Although some developers and end clients opt for the MSCB solution there is still a perception that buildings must have a false ceiling.  With energy sustainability and whole life costs becoming increasingly important this “false ceiling taboo” will be swept away.

Offsite prefabrication of the beams is another significant benefit to the sustainability argument.  Firstly there are no over ordering of the separate components that go into the MSCB since they are part of a Just in Time (JIT) process operated in the factory.  Compared to on site activities waste through over ordering, damage, etc., is more or less eradicated.

Additionally any waste materials can be more easily recycled in the factory and traffic movements can be lessened which is better for the environment.

With MSCBs it’s the first time the architect can style the appearance of the services to virtually whatever appeals most.  It’s not a case of “cost doesn’t matter” either, because the customisation can be achieved with a minimal premium, probably less than 2% of the MSCB value.

This is achieved by manufacturing the façade of the beam or “services raft” from interlocking architectural grade of extruded aluminium.  The shape and visual appearance can easily be changed by using different extrusions.  If new extrusions are required, which is often the case, tooling costs are minimal compared to rolled steel sections.  Because of the very tight  tolerances that can be achieved with extruded aluminium this material is ideally suited for the long lengths used in the manufacture of MSCBs.   The appearance of MSCB running along the  soffit without false ceilings needs to meet the stringent and high standards set by the architect.  They need to produce a straight smooth continuous appearance along the installed lengths of up to 30 metres (see picture 1).  So when you look along the whole length in an open plan office there are no obvious joins, “ripple effect” or alignment problems often associated with rolled steel sections.

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