A chilled beam is a type of radiation/convection HVAC system designed to heat and cool large buildings through the use of water.
They both consist of pipes of water (fin-and-tube) that pass through a heat exchanger contained in a case suspended from, or recessed in, the ceiling.
The passive approach can provide higher thermal comfort levels,[7] while the active approach (also called an "induction diffuser")[8] uses the momentum of ventilation air that enters at relatively high velocity to induce the circulation of room air through the unit (thus increasing its heating and cooling capacity).
[11] Beams can be installed in a number of forms - fully exposed, recessed, or hidden within a suspended or perforated ceiling.
[11] The chilled beams are considered as easy to mount as light fixtures, but require suitable access for service and maintenance.
[11] However, studies of the energy cost-savings of active versus passive chilled beam systems remain inconclusive as of 2007, and appear to be highly dependent on the specific building.
In contrast, hospital patient rooms require higher air quality levels, and thus need more ventilation than cooling and heating load than a chilled beam system is able to supply.
The total cooling capacity of a chilled beam is found through the primary air (Pa) and coil cooling capacity (Pw) values: P= Pa + Pw [12] In design practice it is common to see the chilled beam water side cooling capacity estimated with the following equation: Pw = Qm cw (tw2 - tw1) where Qm is the mass flow rate of water cw is the specific heat capacity of water tw2 is the water temperature exiting the coil tw1 is the water temperature entering the coil [12] The primary advantage of the chilled beam system is its lower operating cost because the system requires much less energy to provide the same heating and cooling effect as a traditional air HVAC system.
[8] 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.
[19][20] Traditional fan-driven HVAC systems create somewhat higher air velocities,[20] which some people find uncomfortable.
[8] 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.
)[11] Chilled beam systems are not recommended for areas with high humidity (such as theaters, gymnasiums, or cafeterias).
[17] Because they are less effective at cooling, passive chilled beam systems are generally ill-suited for semi-tropical and tropical climates.
)[22] 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.
Developed in 1996, it incorporates computer and electrical wiring, lighting, motion-detection sensors, and sprinklers into the chilled beam unit.
[28][29] Chilled beam HVAC systems have been used at Heathrow Terminal 5[30] and Constitution Center (the largest private office building in Washington, D.C.).
[31] The system has also received prominent use at Harvard Business School, Wellesley College, and the American headquarters of the pharmaceutical company AstraZeneca.