Ceiling fans, 20 foot ceilings

[seagravedriver]

I work for a fire dept., and the building I am stationed at has two different size ceilings. One has a 20 foot ceiling and during this summer it has been about 104 near the top of the ceiling, and 94, give or take at 5 feet.

The other bay we have is a 24 foot ceiling, (a newer portion of the same building, there is a man door between), with two ceiling fans that drop about 2 feet. That bay is always 10 to 12 degrees cooler. I asked for two ceiling fans in the bay without them, as that is where our first out units are, and we spend a fair amount of time there. Some of the guys feel that "heat rises, so what good will it do"? Failing to notice the difference in the nearby bay. I have to justify it to our facilities folks to get it done. Any thoughts?
(The bay is 40' wide by 46' deep).

 

[matt_i]

Not sure exactly how you justify it, show them a handheld infrared thermometer result (or however you objectively determined the temp difference). Or get your boss to make a formal request to their boss.

 

[LB-1911]

I work for a fire dept., and the building I am stationed at has two different size ceilings. One has a 20 foot ceiling and during this summer it has been about 104 near the top of the ceiling, and 94, give or take at 5 feet.

The other bay we have is a 24 foot ceiling, (a newer portion of the same building, there is a man door between), with two ceiling fans that drop about 2 feet. That bay is always 10 to 12 degrees cooler. I asked for two ceiling fans in the bay without them, as that is where our first out units are, and we spend a fair amount of time there. Some of the guys feel that "heat rises, so what good will it do"? Failing to notice the difference in the nearby bay. I have to justify it to our facilities folks to get it done. Any thoughts?
(The bay is 40' wide by 46' deep).

Give this a look -

OSHA standards indicate temperatures of 100.4°F (38°C) and above are dangerous for workers, while air temperatures that exceed 95°F (35°C) significantly increase the heat load on the body. When temperature and humidity levels rise, the body’s natural ability to cool itself decreases. While air movement does not lower the actual temperature in a space, the perceived cooling effect can make a person feel up to 10°F (5.6°C) cooler.

Summer Cooling
http://www.bigassfans.com/summer-cooling/


Stratification
http://www.bigassfans.com/heat-destratification/

 

[buddyboy]

look for other differences first.

is the cooler room on the north side of the building?
is the cooler room better insulated?
does the cooler room have different lighting?

once you rule out every difference between the two rooms and the only thing left is the fans then it makes since to get fans

turn off the fans in the cooler room for a day and see what happens. that will be the final proof you need.

but I would have to think that hot air rises and using a ceiling fan to circulate that hot air would not be good... but who knows

 

[Kaizen]

the key is the cooler one is newer construction. most likely with better insulation in the roof.
A fan does not cool the air but just mixes it up. So if at 20 feet its 100 but at 5 feet its 80 then a closed room with fans will equal to about 90. Now if you have the doors open with fresh 75 degree air coming in then it will probably equalize to 80.
In the winter it will take that rising heat and push it back down which might be some energy savings.

 

[kbs2244]

Isn't it common to have the door open at a fire house?
Yes, heat does rise, so..
I would look into the idea of a highly placed exhaust fan.

 

[Architorture]

Is it actually cooler or does it just feel cooler?

Thermal comfort has 4 factors contributing to it. Temperature, humidity, air velocity and radiant temperature.

Could the 2 fans be moving enough air to make the large bay feel cooler when it is nearly the same temperature?

See big *** fans example above. The things work great