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What are different types of chilled beams and how are they different?

+1 vote
  • What is the Active Chilled Beam? 
  • What is the Passive Chilled Beam?
  • What is the Primary air system in Active Chilled Beam?
asked Oct 2, 2014 by Mepanet

2 Answers

+3 votes

The main types are active and passive chill beams. There are several variations. Chilled ceiling systems consist of three main product types: active chilled beams, passive chilled beams, and radiant ceiling panels/sails. Even though these units are commonly referred to as “chilled” products they are also effectively used for both cooling and heating. Both active and passive beams utilize water coils to provide sensible cooling, reducing the total load that must be addressed through the building’s air handlers. Since chilled beams provide sensible only cooling they are best suited for spaces with low to moderate latent loads. This offers considerable potential for energy savings due to the volumetric heat transfer capacity of water and trade-off between fan energy and pumping power. Passive beams consist of a water coil and an enclosure. The enclosure is primarily cosmetic, but helps to maintain even heat transfer across the coil. Passive beams provide cooling primarily through convective heat transfer. A convection current is created where higher density cool air sinks into the space, inducing warm low density air at the ceiling level through the coil. When using passive beams ventilation air must be introduced to the space either through natural or mechanical means.


Active chilled beams (ACB)

An ACB also consists of a fin-and-tube heat exchanger contained in a housing that is suspended from, or recessed in, the ceiling. The primary difference is that an active chilled beam contains an integral air supply. This primary air passes through nozzles, which induce air from the space up through the cooling coil. This induction process allows an active chilled beam to provide much more cooling capacity than a passive chilled beam. For this reason, active chilled beams are more commonly used. They have pipe connections and a primary air connection. ACB are either two- or four-pipe, with the two-pipe design, all zones receive either cold water or hot water. The benefit of the four-pipe design is that some zones can receive cold water for space cooling, while other zones simultaneously receive hot water for space heating.

Primary air system for ACB: To comply with most building codes in the U.S., outdoor air must be supplied to each space for ventilation. And since a chilled beam (whether passive or active) typically does not contain a condensate drain system, the primary air system must also maintain the dew point of the indoor air below the surface temperature of the chilled beam to avoid moisture from condensing on the coil and dripping into the space. Therefore, the purpose of the primary air system for active chilled beams is to:

  • Deliver at least the required amount of outdoor air to each space for ventilation.
  • Deliver air which is dry enough to offset the space latent load and maintain the indoor dew point low enough to avoid condensation on the chilled beams.
  • Deliver enough air to induce sufficient room airflow to offset the space sensible cooling load.


Passive chilled beams (PCB)

Like ACB, the PCB consists of a fin-and-tube heat exchanger, contained in a casing that is suspended from the ceiling. Chilled water passes through the tubes. Warm air from the space rises toward the ceiling, and the air surrounding the chilled beam is cooled, causing it to descend back toward the floor, creating convective air motion to cool the space. This allows a passive chilled beam to provide space cooling without the use of a fan.

Water can carry significantly more energy than air. Although 1 cubic foot (0.028 m3) of air has a capacity to hold heat of 0.02 BTU/°F (37 Joules per Kelvin), the same volume of water has a heat capacity of 62.4 BTU/°F (20,050 Joules per Kelvin).  A metal pipe of water just 1 inch (2.5 cm) in diameter can carry as much energy as an 18" X18" (46 by 46 cm) metal duct of air. This means that chilled beam HVAC systems require much less energy to provide the same heating and cooling effect as a traditional air HVAC system. Water in a passive chilled beam system is cooled to about 61 to 66°F (16 to 19°C), in active chilled beam heating systems, water temperature is usually 104 to 122°F (40 to 50°C). Chilled beam heating systems usually cannot rely solely on convection, however, and often require a fan-driven primary air circulation system to force the warmer air to the ground where most people sit and work.



Chilled beams are more energy efficient than the traditional HVAC systems (with air-side savings ranging around 30 to 40% as it is project specific). Also lower running costs associated with chilled beams make them more attractive for retrofit projects and also a first choice by HVAC designers for new buildings. 

Chilled beams can be further classified into closed active or open active as well as radiant/convective passive chilled beams. Separate fresh air supply and extract systems will be required to maintain humidity and CO2 levels (as per local guidelines/standards) inside the conditioned space. Active chilled beams are also known to be more effective in tandem with displacement ventilation.

answered Oct 2, 2014 by Mepanet
1 more note to this excellent answer: chilled beams are either non-condensing or condensing.  Non-condensing types must operate above dew point of space air, and need no provisions for draining of condensate.  Condensing types are intended to operate even below space dew point and require condensate drains.
+1 vote

I hope that soon someone will start  to  produce Super Active Chilled Beams - here is my concept No 2 .

If there are any interested people I can send other conceptual solutions.

answered Feb 9, 2015 by Piotr Drabecki

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