ENERGY SAVING EQUIPMENT
Rise of the chilled beam
Fan coil units have traditionally been a popular solution for providing air conditioning in commercial buildings. However it is important for consultants and engineers to take stock of latest technology on the market that can both reduce energy consumption and cut running costs. Yan Evans, vice president of the UK sales unit at Fläkt Woods, explains why chilled beams are quickly becoming the go-to choice.
E
nergy efficiency has become a significant factor to consider when designing a new air conditioning system. Figures from the Carbon Trust indicate that air conditioning can increase a building’s energy costs and carbon emissions by up to 100%. Furthermore, the Trust estimates that cooling alone consumes up to 14% of UK electricity.
Despite the fact that FCUs have become more efficient in recent years, especially since the introduction of electronically commutated (EC) motors, in reality they still can’t compete with the advantages of chilled beams. A core reason for this is that chilled beams are significantly more energy efficient, with around 75% of cooling handled by higher capacity water, rather than by having the full load handled by air. In fact, chilled beams offer savings of up to 40% over traditional air conditioning systems. The second factor is that they offer enhanced flexibility for building and system designers, making them the ideal solution for delivering air conditioning, ventilation and high indoor air quality across a whole host of commercial applications, such as offices, hotels, health care facilities and educational institutions. It’s no surprise then that forecasters are predicting the global chilled beam market is likely to grow at an estimated compound annual growth rate of 11.14% between last year and 2020, largely driven by the increase in demand for energy saving in buildings and enhanced thermal comfort for occupants. This makes it the perfect time for HVAC professionals to get on board with what the technology has to offer the commercial
34 August 2016
pipework, which leads to the need for anti- condensation protection.
FCUs also normally need a filter to prevent the coil becoming clogged with dirt caused by the coil becoming wet. In contrast, a chilled beam system needs no condensation protection because the chilled water temperature is typically above a room’s dew point and, as the chilled beam coil is dry, there is no need for a filter.
building sector.
Chilled beams circulate air using the principles of natural heat convection and their major advantage over more common forced-air systems is that they circulate air without the noise and expense of ductwork and air handlers. Typically mounted overhead, the beam is chilled by an external source such as recirculated water and cools the space below by acting as a heat sink for the naturally rising warm air of the space. Water temperatures in chilled beams are higher than in fan coil systems – typically 14°C flow compared to 6°C – which enables the chiller to perform more efficiently. Chiller energy savings for a chilled beam system compared to an FCU can be as much as 35%.
While energy performance will drive many decisions, there are other significant advantages to be gained from chilled beam systems. Initial installation costs are lower, as is ongoing maintenance. FCUs, for example, require wiring for the fan. The way in which FCUs operate also adds to their cost. The low water temperature required causes condensation on both coil and
As well as considering the impact on energy costs of air conditioning systems, specifiers and building owners often need to consider future- proofing. In many building projects – particularly office and retail spaces – the HVAC systems are designed and installed without knowledge of how the space is likely to be divided in the future, so flexibility can be a key consideration. Where there is the likelihood that a building will be re- structured internally during the lifespan of its systems, with walls, occupancy levels and room functions changing, HVAC systems need to be flexible.
One misconception that still exists about chilled beam units is about flexibility. Traditionally they consisted of a 3m rectangular beam that was largely immovable, which is not particularly helpful if the floor plan was likely to change. Today’s chilled beams are considerably more adaptable.
As new generations of chilled beam systems come to market, their ease of installation, potential for energy saving and long term flexibility represent an increasingly attractive alternative to FCUs for the engineer, specifier and end user alike.
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