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.
Reflective surfaces (climate engineering)
Unlike other Energy Star-rated products, such as appliances, this rating system does not look at the entire roof assembly, but only the exterior surface. Consumers (i.e. building owners) may believe that the Energy Star label means their roof is energy-efficient; however, the testing is not as stringent as their appliance standard and does not include the additional components of a roof (i.e. roof structure, fire rated barriers, insulation, adhesives, fasteners, etc.). A disclaimer is posted on their website "Although there are inherent benefits in the use of reflective roofing, before selecting a roofing product based on expected energy savings consumers should explore the expected calculated results that can be found on the Department of Energy's "Roof Savings Calculator" website at www.roofcalc.com. Please remember the Energy Savings that can be achieved with reflective roofing is highly dependent on facility design, insulation used, climatic conditions, building location, and building envelope efficiency."