Ongoing investment in research and development of chilled beams in recent years has brought to the UK market a wider range of solutions than ever before. It isn’t just a matter of designing new ‘bells and whistles’, or increasingly complex technology as Iskender Gençer of Trox UK explains.
Development has followed a number of different paths in recognition of the fact that specifiers have a range of priorities, from lowest upfront cost and fastest delivery to highly-specific bespoke requirements to achieve the aesthetic ambitions of the architect. The choice of chilled beam models has also been extended to solve the many challenges posed by design or layout of the full gamut of building stock.
So what options are available? And how can they help deliver tangible benefits for end customers?
Active chilled beams
The most obvious difference between active and passive chilled beams is, of course, the functionality. Passive chilled beams deliver cooling whilst active chilled beams are designed to provide both cooling and heating. The ventilation capabilities also vary. A passive chilled beam is not a ventilation device. An active chilled beam, however, delivers cooling by inducing room air through its coil by the help of the primary air supplied into the space through nozzles. Fresh air is delivered via an integral plenum.
Beyond these obvious differences, active chilled beams often provide valuable opportunities in applications with higher than average requirements. For Newcastle’s new Sixth Form College, for example, achieving the optimum indoor environment for learning was a key requirement, as was energy efficiency. The 11,000 square metre building, incorporates specialist facilities including dance and drama studios and laboratories in addition to large social spaces. The building incorporates a number of sustainability features, including a green roof but the usage patterns of the site meant that the HVAC system had to adjust to widely differing occupancy levels in zones across the site throughout the day without wasted energy.
The Multi Service Chilled Beams (MSCBs) chosen for the site were based on Trox DID632 active chilled beam models which utilise energy efficient air-water technology. This solution is ideally suited to the high cooling loads at the site, combining the aerodynamic properties of ceiling diffusers with the energy benefits of load dissipation using water. The chilled beams supply heating, cooling and ventilation throughout the building as well as incorporating lighting. The Trox DID 632 MSCB achieves a higher induction ratio than standard models, delivering high levels of cooling with lower fresh air volumes. Energy costs associated with the system can therefore be reduced via optimum cooling output achieved with less fan energy consumption in the AHUs.
Passive chilled beams
It should not be assumed however that passive chilled beams are limited in their capabilities. Passive chilled beams can be used as supplementary components to reduce the heat loads at the perimeter if poor façade is in question. In addition they provide more flexibility compared to active chilled beams, where demand based ventilation is a requirement to deal with fluctuations in occupancy levels.
A Trox passive chilled beam type TCB-RB, either recessed or exposed as an MSCB, can help deliver sensible cooling of up to 100 W/sqm maintaining comfort (given a typical office application). This, when coupled with a demand based ventilation system controlled by Trox VAV damper range that allow pressure independent variable air flow control, helps achieve increased flexibility in meeting ventilation demand with improved energy efficiency.
Commodity/recessed chilled beams
Early in the development of chilled beams there was a perception that projects with tight budgets could not afford them. This should no longer dissuade specifiers, as manufacturers now have within their portfolio a number of ‘workhorse’ models that deliver the logistical, aesthetic, performance and energy efficiency benefits of a chilled beam system at even more competitive capital costs.
These beams mounted flushed into a suspended ceiling can function as direct dimensional replacements for ceiling tiles and have practical benefits. Specifiers favour the flexibility these offer, making use of the smaller runs, and modular design for greater choice of internal layout. Their ease of design and comparatively short lead times make them a firm favourite with customers. All types of chilled beams in general have significantly lower maintenance cost, and this when coupled with unmatched energy efficiency credentials means life cycle costs of a chilled beam system is very difficult for an alternative technology to compete with.
Bespoke chilled beams
In recent years it has become increasingly common for chilled beam designs to go beyond the practical, to create an interior design impact of their own. To create a raw, industrial look for the new global headquarters of O’Neill (the original California surf, snow and lifestyle brand), the architect wanted to put the inner workings of the building (such as pipework, ducting and wiring) in full view.
The bespoke designs chilled beams created make a design feature of exposed drop rods and connections to reflect the edgy identity of the brand. The architect’s vision for the space removed any idea of a false ceiling, providing concrete slabs onto which the beams are mounted. Whilst it would have been quite feasible to conceal the air inlets at each end of the beam, it was decided that using an exposed side entry spigot as a design feature was more in keeping with the architect’s intentions.
Exposed MSCB (Multi-Service Chilled Beams)
Exposed beams can have advantages for both new builds and refurbishments in that they enable the architect to do away with the need for a suspended ceiling. All services (to include heating, cooling, lighting, ventilation, PIR sensors, fire prevention, and audio services etc) can be incorporated into the MSCB design. The units are off-site manufactured and are plug and play to speed up installation. Exposing the ceiling slab also helps make use of increased thermal mass.
This has proved particularly useful in refurbishment projects. For the refurbishment of 157 – 197 Buckingham Palace Road – an imposing art deco building built in 1939 as an air terminal and which now provides the London headquarters of the National Audit Office – exposed beams solved several practical challenges.
A number of services needed to be introduced, in a building not originally designed for this purpose, whilst remaining true to the architect’s ambitions for the space. In addition, the low floor to ceiling heights of 2.6m made the use of suspended ceilings problematic. For this project, a design committee (which included the architect and Trox engineers) collaborated throughout the process. During development, a full laboratory test of the chilled beam, made it possible to assess the aesthetic impact of the beam as well as its thermal, audio and lighting performance.
As you can see, the choice of chilled beams is extensive but what is important to remember is that each category (active, passive, commodity/recessed, bespoke or MSCB) has something valuable to offer.