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.
Air conditioned clothing
One advantage of air-cooled clothing is that it requires much less energy to cool people down than to cool down their entire environment. For instance, an air cooled shirt uses 4,400 mAh of power for 8.5 hours on the fastest fan setting, while an average central air conditioning unit uses 3000 to 5000 watts of power. In some cases, the purpose of air-conditioning is not to cool down the objects in the room, but the people. Directly ventilating clothing is therefore far more efficient. A 2012 New York Times article reported that gases commonly used in air conditioning absorb some 2,100 times more infrared radiation per ton than carbon dioxide, and due partly to increasing use of air conditioning in the developing world (particularly in tropical areas like India, Malaysia, Indonesia, Brazil, and southern China), air conditioning is projected to contribute to some 27% of the overall greenhouse gas emissions by 2050. Although there are some ideas for room air conditioning units that do not significantly contribute to producing greenhouse gases, none of those options are yet on the market.