Fan coil unit prices are much lower than chilled beams, meaning that they offer the most competitive solution, according to Andrew Sargent.
Figures recently released by research organisation BSRIA show a dramatic change in the market place between fan coils and chilled beams. According to the latest BSRIA/HEVAC survey figures, the fan coil market value was more than double that of the active chilled beam value in 2010. Active chilled beams include both commodity beams and active multi service chilled beams. The value includes the product unit cost and not any design or installation work.
With multi service chilled beams, the value of some of the components such as the lights and lighting control can be included in these chilled beam figures.
Conversely, the value of passive beams has not been included and, as this is a relatively low figure, it is most likely that these two issues cancel each other out.
So, how has this dramatic change to fan coils occurred and will this trend continue? To answer these questions it is interesting to look back at what has happened. It was not until the mid-1990s that one or two projects used the new and novel concept of chilled beams.
At that time, multi service chilled beams were introduced, particularly for low height refurbishments and these gave a significant boost to the total market figures. The biggest market driver, however, was the building regulations launched in 2002 in which the focus was very much directed towards carbon emissions. When subsequent regulations were introduced, it was made clear that this could become a progressively more important issue.
Between 2003 to 2007, annual growth rates within the chilled beam market of up to 40 per cent were recorded and chilled beams looked set to overtake fan coils as the most popular terminal air conditioning system. At this time, chilled beam manufacturers were able to claim an improvement in carbon emissions of up to 20 per cent compared to fan coils and it was clear that this gap, at a time when the focus was on energy, would strongly favour the chilled beam option.
Fan coil manufacturers were well aware of the erosion of their market and, in the last few years, they have introduced efficient fan coil units using EC motors and, more recently, the concept of variable air volume.
Specific fan power (SFP) - a measure of the ability of the fan coil to turn the power in terms of Watts consumed into air volume (litres/second), - is an important measure of energy efficiency of fan coil systems.
So, an SFP of 0.8 W/l/s included in the 2002 Building Regulations meant that, for every litre per second of air volume, 0.8 Watts was consumed by the motor. Figure 1 shows how the specific fan power has been reduced to as low as 0.15 W/l/s for a fan coil.
Most fan coil companies procure their fan decks from specialist suppliers and most use a European manufactured EC motor made by one company. This specialist motor for fan coils appears to have been developed to directly replace the AC motor replicating the design of an AC fan deck resulting in an array of small EC motors each motor having an individual fan. This means that most fan coil units would have multiple fans between three and five fans depending on fan coil size.
My own company designs and manufactures its own fan decks and we use the expertise of our American parent company, Nailors, who procure their EC motors from a USA source.
They were able to design the fan deck right. The fan is horizontally mounted and, rather than an array of small single fans, there is just one larger fan and motor. These highly energy efficient fan coil units have completely changed the market situation and, as revealed by BSRIA, the fan coil market is now twice the size of the chilled beam market.
Neutral energy argument
So what will happen in the future and what will become the market drivers now the energy argument is neutral? With low demand in the marketplace and companies trying to win business, price is going to become even more important than it already was.
Fan coil unit prices are much lower than chilled beams, meaning that they offer the most competitive solution. If prices are a major factor then, clearly, the fan coil market will continue to outperform chilled beams.
There are, however, other considerations, including the ability to heat and cool through one unit. Virtually all fan coils are four-pipe heating and cooling because they incorporate a fan which can avoid any risk of stratification during the heating cycle. Chilled beams, on the other hand, are normally supplied cooling only; they will then require low level heating which can actually impinge into the space and reduce the lettable area.
Most of the commercial office sector is a property developer-led market and flexibility of the occupied space is of paramount importance because, often, the tenant is not known. Chilled beams can be inflexible in terms of partioning lines and the design has to incorporate specific positions for partioning, whereas, with fan coils, a more flexible approach can be taken by activating or blanking diffusers and spigots above the ceiling as required.
The future for fan coils is, in my opinion, favourable. For the reasons I give above, I see them becoming increasingly popular and, in the process, relegating chilled beams to a niche market option.
• Andrew Sargent is general manager at Advanced Air