How much energy can fan save over air conditioner?
The basic notion is that moving air (from ceiling, whole-house, or portable fans) makes you feel cooler, so you can turn up the air conditioner thermostat or turn it off altogether. Whole-house fans are a potential substitute for air conditioning, since they move large amounts of air through the house and require open windows. Savings from using a whole-house fan can be large (it uses 20% or less of the energy of a central air conditioner on a per-hour basis, although they usually need to be used for fewer hours). Also a whole-house fan provides good comfort levels when it’s not too humid or too hot outside (night time). Studies by the Florida Solar Energy Center (FSEC) show that ceiling fans can save energy *if the occupants turn up the A/C thermostat*. Unfortunately, most people don’t adjust the thermostat. Often people leave them on even when no one is home, which can result in negative savings.
Research from FSEC indicates that whole-house fan savings are quite variable, ranging from about 10% to 65%. This range is due to the effect of climate; a milder climate will see savings toward the upper end of that range. FSEC found that if the air conditioning thermostat is set 2o F higher when using ceiling fans, the savings will be 14%. (With a higher thermostat setting, savings are higher.) If the thermostat setting is not changed, electricity consumption will actually increase by 15%. FSEC’s survey of actual behavior showed no measurable savings from cooling fans (i.e. in energy terms, the ceiling fan and the A/C were a wash). There is at least one efficient ceiling fan that uses less energy and has an occupancy sensor (on some models).
Bottom line: Fans can save energy if the air conditioning thermostat setting is increased and if the fans are turned off when no one is home.
Source:www.radiant-heat-floor-methods.com