Sunday, August 2, 2009

How bad is running the A/C for the environment / energy efficiency?

I've decided to turn off the A/C in my 2 bedroom apt and stick with fans, hoping to conserve energy. But if I am running 3 fans (+ 1 ceiling fan) on high 24/7 is it still better than powering the central air?

How bad is running the A/C for the environment / energy efficiency?
Yes, 4 fans use less power than the A/C. A fan uses about 100 watts or less. The A/C uses 1,000 watts or more. My central A/C uses 5,000 watts! But do not run the fans in an empty room. Fans do not cool the air. A thermometer in a room will not go down even one degree when the fan is on. Fans only help the human body to cool itself better by enhancing evaporation from the skin. If you cannot feel the breeze from the fan, it isn't doing any good at all. A fan running at any speed in a room with no people in it is just a waste of electricity. Last person out of the room turns the fan off and the first one back in the room can turn it on.
Reply:By the way, I would like to know how much per hour it takes to run a unit such as the Kenmore Model 580 Series which I believe puts out 8,000 Btu's. Report It

Reply:A typical 8,000 BTU A/C uses about 800 watts. That is 0.8 kilowatts. So in one hour it uses 0.8 kwh. My electric rate is about 8.5 cents per kwh, so that unit would cost me about 7 cents per hour to run. Report It

Reply:It's cheaper than the cost of a heat stroke.
Reply:I don`t really care... My province has one nuclear power station for street lightning, and the rest is hydropower!!!


But as far as you are concerned, A/C don't really used more power than fans! Since the thermal exchange is supply by a pump and a fan... So you end up using 2 engines in the same device. And you are using 3 fans... Which mean you use more energy than using only your A/C
Reply:Check the wattage of each appliance and compare. Note, though, that an air-conditioner compressor cycles on and off, and rarely runs 100% of the time. For a true comparison use a watt-hour meter (~$30-$50) that integrates power and time.


My off-the-cuff guesstimate:


Each fan uses ~80 W and runs perhaps 12 hr/day, for ~90 kW/hr per month.


A 5,000 BTU (~5 megajoule) (a small room air conditioner), EER of 10, might use 700 W with compressor on, 100 W with just fan. If it averages 50% duty cycle (~400 W avg.) and is on 12 hr/day, then it would run ~150 kW/hr per month.


BTW, I sometimes use one room air conditioner to cool the whole house, but need to run a fan or two between rooms. Using a small air conditioner lowers humidity more effectively than using an oversize unit, which is more important in the the climate in which I live.
Reply:Well, you didn't tell us what kinds of fans and everyone seems to be assuming they're small ones. You can probably use a combination of the two to keep things comfortable, conserve energy and mitigate environmental impacts. Use the A/C to bring the temp down, then turn it off and use the fans to keep the cool air distributed evenly. But also keep the curtains or blinds drawn on the sunny side of the house to keep the inside air from heating up again.





But to be safe, check your fans and air conditioner with the ratings offered by Consumer Reports or another consumer group. And consider this advise from the Consumer Reports site:





"And before you put on a cotton sweater to ward off a slight chill from the AC in summer, consider that for every degree you raise the thermostat setting, you can expect to cut your cooling costs by at least 3 percent."
Reply:Air conditioning uses an enormous amount of electricty, which results in most cases in large amounts of carbon and other pollutants being emitted into the air as the power is generated.
Reply:It'll cost you more money on your electrical bill, that's about it. It's not going to destroy the environment, that's a bunch of BS.

anther

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