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A chilled beam is a type of radiation/convection HVAC system designed to heat and cool large buildings. Pipes of water are passed through a "beam" either integrated into standard suspended ceiling systems or suspended a short distance from the ceiling of a room. As the beam chills the air around it, the air becomes denser and falls to the floor. It is replaced by warmer air moving up from below, causing a constant passive air movement called convection, which cools the room. Heating works in much the same fashion, similar to a steam radiator. There are two types of chilled beams. Some passive types rely solely on convection, while there is a "radiant"/convective passive type that cools through a combination of radiant exchange and convection. The passive approach can provide higher thermal comfort levels, while the active type uses the momentum of ventilation air entering at relatively high velocity to induce the circulation of room air through the unit. A chilled beam is similar in appearance to a VRF unit.
The chilled beam is distinguishable from the chilled ceiling. The chilled ceiling uses water flowing through pipes like a chilled beam does; however, the pipes in a chilled ceiling lie behind metal ceiling plates, and the heated/cooled plates are the cause of radiation/convection and not the pipe unit itself. Chilled beams are about 85 percent more effective at convection than chilled ceilings. The chilled ceiling must cover a relatively large ceiling area both because it is less efficient, and because it provides heating mainly by radiant means. Radiant heating capacity is proportional to surface area.