[Greenbuilding] But What if? / Re: Ceiling Fans at Night

[Frank Cetera]

Ok, granting that the real issue here is that more insulation and
weatherproofing are required, let's continue instead on the issue according
to a case study in which the building occupants cannot afford to spend any
extra money on insulating and envelope work at this time.
*
""We do have a programmable thermostat and have it set for 66 during the
day; at 5pm it goes to 60 and at 7pm it goes to 55 (on the weekends it may
even be lower). Brent's (the building manager) theory is that even at 55,
keeping the fans on all night (and weekends) will keep the space slightly
warmer and therefore the furnace would need to kick in slightly less often.
Our theory is that the energy expended keeping the fans going when the
thermostat is set for the lower temperature is more than that saved by the
furnace kicking in a little less often. Two more details - the heat
registers are at the ceiling level (go figure); the thermostat is on a post
about 5 feet up, near an edge of the room. Any idea who is correct? Do the
fans stay on all the time or can we turn them off at night and on the
weekends?"*

Am most interested right now in the question posed here as to whether or not
*"the energy expended keeping the fans going when the thermostat is set for
the lower temperature is more than that saved by the furnace kicking in a
little less often*"?

I would assume that using a fan or two or three for a full night would be
less energy used than a furnace coming on once or twice to heat a multiple
story structure (maybe around 2000 sq ft - but I would have to confirm the
area) during the night?

~Frank

On 1/5/2011 3:10 PM, Frank Cetera wrote:
> To my understanding, and the research I have done, ceiling fans are
> valuable in circulating warm heated air in the home in winter,
> especially from the ceiling to the lower living areas in rooms.  My
> questions pertains to night time use of the fans.
>
> Even if a programmable is used and the thermostat is reduced to 55 at
> night, would it still be valuable to keep the ceiling fans running at
> night to move the warm air from the ceiling to the living/thermostat
> layer, and thus prevent the furnace from turning on during the night?
> Or should turning the thermostat down to 55 pervent it from coming on at
> all so the fans question is mute?

I often want to just answer questions like this with "you need more
insulation".

I would say that ceiling fans are only useful when you are in the room.
 If your furnace comes on before you want it to, turn down the
thermostat (regardless of temperature).

Proper insulation levels would remove both the need for a fan, and the
need for a set-back thermostat.

Thank You Kindly,

Corwyn

--
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
http://www.greenfret.com/
topher at greenfret.com
(207) 882-7652

~~~~~~~~~~~~~~~~~~~~
Frank Raymond Cetera, President
The Alchemical Nursery
200 S. Geddes St, Syracuse NY 13204
315.308.1372
www.AlchemicalNursery.org
Facebook http://bit.ly/7wthCX
Twitter http://twitter.com/AlchemicalSyr
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