Ceiling fan
A ceiling fan is a mechanical fan mounted on the ceiling of a room or space, usually electrically powered, suspended from the ceiling of a room, that uses hub-mounted rotating blades to circulate air. Ceiling fans typically rotate more slowly than other types of circulating fans, such as electric desk fans. They cool people effectively by introducing slow movement into the otherwise still, hot air of a room. Fans never actually cool air, unlike air-conditioning equipment, they in fact heat the air due to the waste heat from the motor and friction, but use significantly less power (cooling air is thermodynamically expensive). Conversely, a ceiling fan can also be used to reduce the stratification of warm air in a room by forcing it down to affect both occupants' sensations and thermostat readings, thereby improving climate control energy efficiency.
Chilled beam
Active chilled beams are mounted in a suspended ceiling and then anchored to the overhead structure, because T-bar ceilings cannot support the typical operating weight of a chilled beam. They are generally wide, and require less than of overhead space. A typical wide chilled beam system generally weighs about per length of the beam. Chilled beams are generally installed so that the center of each beam is no more than from the center of the next beam. Some architects and end-users dislike the beams because they do not cover the entire ceiling so ducts, wiring, and other infrastructure can be seen. Some designers have installed one chilled beam system around the building perimeter (where temperature differences can be the greatest) and another in the interior of the building, to better control temperature throughout the structure. Higher system performance may be obtained by increasing the static pressure of the air in the building. The systems generally need little cleaning (vacuuming of dirt and dust from the fins every five years).