Multi service chilled beams are inceasingly popular, says Fläkt Woods' Linden Shuttleworth.
The requirements of Part L in the UK and a global desire to reduce energy consumption have led consultants to find new ways to save energy, and one major beneficiary of this has been the multiservice chilled beam (MSCB).
Recent developments have seen these functional beams modified for a variety of applications including schools, hospitals and universities, laboratories and - increasingly - office buildings.
By bundling together building elements such as lighting, sprinklers, communication cables, multiservice chilled beams can dramatically reduce building construction time since contractors need only install one unit rather than multiple items; typically this will cut installation times by 25 per cent.
Reducing height requirements
And, where space is important, chilled beams reduce the floor-to-floor height required because less space is needed for ceiling systems.
For new construction, for example, this may allow five storeys at the height normally needed for four, which would offer considerable construction economies. For retrofits, it may allow larger overall room heights.
A benefit of these beams is that maintenance is simpler, less frequent and less expensive than fan coil systems. Multi-service beams do not have fans or filters and, because the surface temperature must be held above the dew point, they have no condensate lines or traps.
Their simplicity means they are less expensive to maintain than traditional chilled water systems because of fewer moving parts. In addition, they use warmer water (chilled water temperatures of 14 deg C flow and 17 deg C return), saving money on energy. These higher temperatures mean that there is potential for significant periods of free cooling.
Since the beams can be factory optimised to suit 'plug and play' situations, savings are made in installation and commissioning times for which both the main building and installation contractors benefit in overall cost savings and, because they can be individually fashioned, they can blend to fit with any building feature or environment.
Finally, chilled beam systems have low airflow velocities, which reduces draughts. Low pressures and remote fans also lead to relatively quiet work zones.
Active MSCBs work in the same way as conventional ventilated chilled beams, by ducting primary air to the beams and then discharging it through calibrated nozzles or punched holes located internally within the beams. This encourages room air to pass over the beam's cooling coils before combining with the fresh air and being supplied in a horizontal discharge pattern via the integrated linear slot diffusers.
The cooling is achieved through a combination of induced airflow and heat exchange across the cooling coils. The discharge velocity is high relative to a small mass of air. The characteristics and energy of this jet induce warm room air across the cooling coil (which absorbs the heat from the air stream and cools it) and into the primary air stream.
Lower air stream velocity
Thus, the mass of cool air induced into the primary air stream has the effect of reducing the air stream velocity as it mixes within the plenum chamber prior to discharging from the beam. This maximises comfort levels by preventing draughts.
Chilled beams provide savings by replacing fan energy with pump energy. They use pumped chilled water instead of blowing cold air. Water has much higher heat capacity, both by mass and volume. In typical pump and fan arrangements, this has been shown to translate into fan energy being reduced by a factor of seven.
Now, with the development of twin-wheel and even triple wheel systems, it is possible to take the advantages of the chilled beam system and provide fresh air controlled on its dew point without the inherent energy inefficiencies of traditional air handling units with dew point control.
Research is on-going and it is possible that in the near future the active MSCB will meet cooling loads up to 120 W/sq m with total airflows much reduced.
Pharma firm benefits from MSCBs
A new highly visible office complex in Cambridge has used multi-service chilled beams to help create the 3m full-height ceiling requirements of NAPP Pharmaceuticals for its three office buildings on the Cambridge Science Park.
NAPP knew it wanted generous office heights within the 110,000 sq ft of office space and thanks to early co-ordination it was able to save up to 25 per cent off the fit-out costs, by using chilled beams.
The office space has been designed to be flexible, achieving the prerequisite floor to ceiling heights as well as fully accessible ceilings and raised access floors. Feature walls, relaxing zones featuring bespoke aluminium MCBSs and exhibits are sprinkled throughout the open space, with enhanced views for the occupants and calculated daylight infiltration.
'We've created a fertile inspiring environment to encourage and nurture great thinking. The open spaces and the feeling of height help to draw people together, and relaxing zones help create a chance for the interaction of people and ideas,' says Bob Chart of NAPP Pharmaceuticals.