[Greenbuilding] Ceiling Fans at Night?

[JOHN SALMEN]

Paddle type fans are not that efficient or comfortable in heating mode. I
feel a lot of air movement can be accomplished by properly sized and placed
room to room air grilles as well as integrating some type of low volume fan
assisted ducting or plenum at high ceiling points that can be used as a
return (winter) or HR exhaust (winter) or straight exhaust (summer).

Air flow from a heating source and where it washes walls and ceilings can be
fairly predictable so creating a plenum or collecting air is not that
difficult to create. Using interior wall cavities as ducting to a fan
assisted register can work well to pull heat. 

One simple design I worked with for passive assist with no additional fan
power consumption was to create a dropped plenum in a cathedral peak and
utilized the ceiling gypsum which can work effectively to store heat (simply
feel the ceiling over your woodstove) and that can be transferred to water
coils as preheat for DHW. The slight cooling of the ceiling can then help
air movement by breaking the stratification. 

JOHN SALMEN ENVIRONMENTAL DESIGN
4465 UPHILL RD,. DUNCAN, B.C.  CANADA, V9L 6M7
PH 250 748 7672 FAX 250 748 7612 CELL 250 246 8541
terrain at shaw.ca

-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Ron
Cascio
Sent: January 6, 2011 8:36 AM
To: Environmentally-preferable design, construction, building elements
Subject: Re: [Greenbuilding] Ceiling Fans at Night?

Ceiling fans work the same on the human body in both summer and winter; 
convective cooling. It is my belief that a ceiling fan is useful in winter 
only when there is a large degree of temperature stratification in high 
ceiling areas and the fan is able to push that hot air (which wants to stay 
up there) down to a lower level at a very low velocity, low enough as to not

cause convective cooling to the occupants of that area.

In short, I think it is a hard thing to accomplish.

Ron


----- Original Message ----- 
From: "Corwyn" <corwyn at midcoast.com>
To: "Environmentally-preferable design, construction, building elements" 
<greenbuilding at lists.bioenergylists.org>
Sent: Wednesday, January 05, 2011 4:40 PM
Subject: Re: [Greenbuilding] Ceiling Fans at Night?


> 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
>
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