Energy Efficient Systems
Active Chilled Beam - Acticool
With the introduction of high induction active chilled beams a wide range of cooling loads can be achieved up to 200w/m2 which in today’s modern buildings should cover virtually all the cooling loads.
- No condensate pump
- No fans
- No motors
- No moving parts
- No filter
- No consumables
- Simple on/off control valves
- 3 year inspection
- 20 year life span
Maintenance and Whole Life Costs
One of the main advantages of chilled beams is the low level of maintenance required. This generally leads to low whole life costs
Very good comfort levels can be achieved utilising chilled beams. The air velocities are low within the occupied space and since the supply air temperature is around 16 degrees there is not a high temperature gradient with chilled beams.
Noise levels are also very low with NR35 being easily achieved in the absence of a fan in the unit.
The chilled beam has two important energy considerations when compared to the fan coil unit.
Firstly there is no secondary or terminal fan unit since the beam operates by inducing air with nozzles (active). Usually a large quantity of fan coils are used even on an average sized project so the total kW consumption of these terminal fan units can be significant particularly where they are left running all the time (i.e. constant speed as opposed to variable volume VAV fan coils).
Secondly elevated chilled water temperatures of 14/17 degrees are utilised as opposed to 9/14 degrees usually associated with fan coils. This provides a further opportunity for “free cooling” thereby reducing energy usage.
Chilled Beam Operation
As can be seen from the diagram the operation of the active chilled beams is relatively simple. Fresh air is supplied along a horizontal duct at the top of the unit. The air is forced through nozzles which are mounted in this horizontal duct and positioned to get maximum air entrainment.
As these jets of air dissipate in the chilled beam exit diffuser they induce room air to pass through the centrally mounted perforated diffuser and over the coils. These coils are normally used for cooling but they can provide heating as well. The 4 pipe heating and cooling chilled beam has coils with twin circuits. Since cooling is the main requirement the coil is designed to meet the maximum cooling load. On the heating cycle the hot water is conveyed to the centre of the coil by a separate micro bore copper pipe and achieves the relevant heating with no impact on the cooling potential.