Keep the AC on?

Question

Is it more economical to turn the AC off during the day when no one is home, or just to leave it running 24/7?

Answer 1

Turn the A/C off. Conserve energy. Have you seen the news and headlines? There are rolling blackouts everywhere due to record numbers in power consumption from A/C units.

Here are a few headlines and links to the articles urging us to conserve energy:

Xcel Energy Urges Customers to Conserve -
http://www.kcbd.com/Global/story.asp?S=5232550&nav=3w6y

Taft makes energy conservation plea -
http://www.centralohio.com/apps/pbcs.dll/article?AID=/B8/20060803/NEWS01/608030319/1002&template=B8

Hot Weather Spurs Energy Conservation -
http://www.wcax.com/Global/story.asp?S=5232258&nav=menu183_15_2_1

Utilities urge continued energy conservation -
http://abclocal.go.com/wabc/story?section=weather&id=4430144

Use fans instead. Close your east and south facing window shades during the day to prevent sunlight from heating up your home.

Install more insulation in your walls and attic. Replace your windows. Plant deciduous trees near east and south facing windows and doors to block sunlight during the summer months.

Answer 2

I too am a heating and cooling professional. I too get asked this a lot. I read all the answers you have recieved so far and for the most part I agree with "Mr.Cool". A 10 degree difference is enough to notice savings. You must understand however the basics about how an air conditioner works.

Most people do not know this but an air conditioner does not make cold. It only removes heat. If there is less heat to remove, in the first place, then the air conditioner will not turn on as often, or run as long, no matter what the thermostat is set for.

If you wish to make a major impact on you utility bill, you need to change how you think. Pretend it is Wintertime. Are all of the storm windows down ? Hows the weather stripping ? Do you need to recaulk anything ? What about turning off extra lights, they get very hot (put your hand next to one). It is funny people think about ways to keep cold air out in the Winter, bur seldom think about ways to keep the hot air out in the summer.

Anything and everything that works in the Winter also works in the Summer. Also another way to save is to keep the blinds closed, Curtains too. Again if you can keep the hot out, then you do not have to work as hard removing that which does come in.

I do disagree about the automatic setback aka programmable stats. I think they are a good idea. While it is true they are a convinance, and may make me appear lazy, to me it seems kinda silly to not use the "easy way". A programmable stat never forgets to turn me up or down. I remember more than once being half way there and remembering I forgot to adjust the thermostat.

Plus you you follow a pretty regular schedule you can tell the air conditioner to come on an hour or so before you get home, so the house is nice and comfortable the second you walk in the door.

Answer 3

I make people comfortable for a living. I am in the a/c business and I often get this very question. There are too many variables to give a blanket answer that will cover every case. I can tell you what I do here at home. When we are not here, I change the thermostat 10 degrees. That way in the summer I still have dehumidification in the house and when we come home and reset the thermostat, the system gets back to where we want it quickly.
I sell a lot of programmable thermostats, but I do no use one myself. When we walk in we set the thermostat. simple as that. Often we try to make things more complicated than they are. I condition a 2000 sq. ft. all electric home for $160 per. month with a air source heat pump. I set my thermostat in the summer when we are here to 70, in the winter 66. When we are not here , I move it 10 deg. above in the summer and below in the winter.

Remember this is a comfort product. It does not do any good to save a truck load of money and not be comfortable. You have to be somewhere in between.

Answer 4

I have seen this question 3 or 4 times since I started on Yahoo Answers. The outcome is usually 50/50, half saying yes and half saying no.

Personally, I raise the temperature on mine to 85 (using a programmable thermostat) during the day and at night. I have been doing so for the last 15 years and believe it has reduced my bills. The rule of thumb I have heard is that if you are going to be gone for several hours (4-5), it is economical to put it on a higher temp. However, I have never seen a definitive answer on this.

(edit) I did a quick search and found this

http://www.nationalgridus.com/non_html/brochure_heatcool.pdf

Answer 5

Depends on how hot it as at your house. At my parents' house in Colorado, they turn the A/C on only in the afternoon, when it gets above 80, then turn it off once the sun sets.

In North Carolina and Florida, where I have lived, you're better off leaving it on all the time, but setting it to a higher temperature if you're going to be gone for an extended period of time.

Answer 6

You don't have to turn it off, just adjust the thermostat up to a high temperature. It make the house a little uncomfortable at first when you get home, but should end up saving you money.

Answer 7

When not at home turn it down,,instead of running it at say 70,when not home run it at 73 or 74,,that way there its easier on the power

Answer 8

i leave mine at 82 if you let it get over 85 in your house the ac wont be able to cool it off fast enough when you get home

Answer 9

a guy I know that works at the electric company said that if you turn it off that it has to work harder to cool the house down when you do turn it back on. Cause it has to actually cool down every single thing in your house to get the house cool.

Answer 10

If its real hot, it will probably use more power cooling off a hot house than it will just running all the time..