Briefs: Chilled beams take off

Several MIT buildings now boast what looks like slim, fin-tubed radiators in ceiling cavities. These cooling devices are chilled beams. They use water, not air, to remove heat from a room. The potential energy reduction of using chilled beams instead of a traditional air-conditioning system ranges from 20 to 50%, depending on the type of system, climate and building. According to MIT, chilled beams take 1/10th the volume of fresh air needed for traditional air conditioning and require less ductwork, smaller ducts and smaller fans. However, some aspects need to be carefully addressed, especially humidity control in the cooled building in order to prevent water condensation on the diffuser's coil. MIT will incorporate two types of chilled beams: active and passive. Active systems tie into the building's air supply ducts, mixing supply air with cooled air and distributing it through diffusers. Passive technology relies on warm air rising to the beams to be cooled. It then descends without the assistance of fans. In both cases, water cooled to between 15-18°C is pumped from a chilled water system to the coiled piping inside the beam.