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.
Heat recovery ventilation
Energy saving is one of the key issues for both fossil fuel consumption and protection of global environment.The rising cost of energy and the global warming underlined that developing of the improved energy systems is necessary to increase the energy efficiency while reducing greenhouse gas emissions. The most effective way to reduce energy demand is to use energy more efficiently. Therefore, waste heat recovery is becoming popular in recent years since it improves energy efficiency. About 26% of industrial energy is still wasted as hot gas or fluid in many countries. However, during last two decades there has been remarkable attention to recover waste heat from various industries and to optimize the units which are used to absorb heat from waste gases. Thus, these attempts enhance reducing of global warming as well as of energy demand.