Chilled Beam - Advantages and Disadvantages

Advantages and Disadvantages

The primary advantage of the chilled beam system is its lower operating cost. For example, because the temperature of cooled water is higher than the temperature of cooled air but delivers the same cooling ability, the costs of the system are lower. Because cooling and heating of air are no longer linked to the delivery of air, buildings also save money by being able to run fewer air circulation fans and at lower speeds. One estimate places the amount of air handled at 25 to 50 percent less using chilled beam systems. By being able to target the delivery of clean outdoor air where it is needed (rather than injecting it into the entire system and heating or cooling it), there is a reduced need to treat large amounts of outdoor air (also saving money). In one case, the Genomic Science Building at the University of North Carolina at Chapel Hill lowered its HVAC costs by 20 percent with an active chilled beam system. This is a typical energy cost savings. Chilled beam systems also have some advantages in that they are almost noiseless, require little maintenance, and are highly efficient. Traditional fan-driven HVAC systems create somewhat higher air velocities, which some people find uncomfortable. Chilled beam HVAC systems also require less ceiling space than forced-air HVAC systems, which can lead to lower building heights and higher ceilings. Since they do not require high forced air flows, chilled beam systems also require reduced air distribution duct networks (which also helps to lower cost).

Chilled beam systems are not a panacea. Additional ductwork may be needed to meet minimum outdoor air requirements. Both types of chilled beam systems are less effective at heating than cooling, and supplementary heating systems are often needed. Chilled beam systems cannot be used alone in buildings where the ceilings are higher than 2.7 metres (8.9 ft), because the air will not properly circulate. A forced-air circulation system must be employed in such cases. If the water temperature is too low or humidity is high, condensation on the beam can occur—leading to a problem known as "internal rain." (In some cases, drier outside air can be mixed with the wetter inside air to reduced interior humidity levels while maintaining system performance.) Chilled beam systems are not recommended for areas with high humidity (such as theaters, gymnasiums, or cafeterias). Because they are less effective at cooling, passive chilled beam systems are generally ill-suited for semi-tropical and tropical climates. Hospitals generally cannot use chilled beam systems because of restrictions on using recirculated air. Chilled beam systems are also known to cause noticeable air circulation which can make some people uncomfortable. (Passive air deflection devices can help disrupt these air patterns, alleviating the problem.) Some designers have found that enlarging the ducts around active chilled beam systems to increase air circulation causes echoes in working areas and amplifies the sound of water moving through the pipes to noticeable levels.