Paper 7: Volume 4 No.2 September 2005 Edition
Saving Energy with
Indoor Air Movement
Richard
Aynsley
Big
Ass Fan Company
800 Winchester Road
Lexington
,
KY
40505
USA
Abstract
The cooling effect of indoor air movement from circulator fans has been
discounted in many strategies for increased energy efficiency. Standards
such as ASHRAE 55-2004 clearly provide thermostat offset guidance for
indoor air movement to maintain the comfort of sedentary occupants.
The Standard is ambiguous on the cooling effects of air movement
for non-sedentary activity.
US
utility company Exeloncorp, has indicated that each 1ºC increase in
summer thermostat setting will save 5.4% to 7.2% of cooling costs.
Another study has shown that a residential air conditioner costs 11
times more to operate than ceiling fans.
In winter, air movement that thoroughly mixes indoor air can save
20% to 30% of heating costs. A
study in
Thailand
has quantified cooling effects of air movement for velocities up to 3 m/s
and relative humidity from 50% to 80%. The US Naval Medical Command
published relative cooling effects of air speed over man from 0.2 m/s to
10.9 m/s. Air movement is widely used in livestock barns to cool dairy
cattle, pigs and chickens. Gusting
air flow can significantly enhance the cooling effect at low velocities.
It is concluded that strategies for energy efficiency that discount
the benefits of increased indoor air movement forfeit significant energy
savings. Further research on the cooling effects of indoor air movement
for higher velocities, lower clothing insulation and higher activity
levels is needed.
Key words:
winter comfort, summer
comfort, indoor air movement, energy savings, adaptive cooling, thermal
comfort, destratification, energy efficiency, circulator fans.
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