Is it cheaper to keep your A/C on all the time or turn on and off?

[Muushka]

I've just been contemplating this subject. We are leaving for DW next Friday. We'll be gone a week. We won't turn off the A/C, but how high should we set it? I was thinkng 80, but now am wondering if that's too high. Keeping in mind, that it's in the high 90s here right now, so it's definitely A/C weather. TIA for any advice.

We set ours at 83 when we are gone. It takes a little while to get down in temp, but I think the savings makes it worth while.

I've been wondering the same thing as OP....thanks for clarifying. And sorry if this is highjacking but does it help on the electric bill to turn up the thermostat a few degrees at night and then back down in the morning (more specifically while we're asleep)? Or would that also be counterproductive?

We keep ours at 82 during the night. Neither one of us is a big fan of the 'ice cold bedroon' and we have a ceiling fan that cools us off just fine.

We also installed dampers on our heat/AC. In the summer we send the AC upstairs and in the winter we shut it off because the heat rises. We have very reasonable heating and cooling bills.

 

[estherhead]

As for night, I like be cooler too, but if you do want it warmer at night & have a programmable t'stat just have it go back down to temperature before the heat of the day starts.

As for the PP, attic vents are essential as well for optimal cooling. Hot air gets trapped in your attic & acts like a blanket keeping your house nice toasty. If you have vents in your attic (basically holes under the eaves) then the hot air can be pushed out, saving you cash! If you don't have them, it's a cheap fix.

 

[Gina]

Okay, with all due respect, this is the budget board! Who is keeping their a/c in the low 70's? If you want to save money, stop turning it up and down and just keep it at at least 78. Ours stays at 79-80, and I find that very comfortable with the lack of humidity. The point of air conditioning is to make the heat comfortable, not be able to hang meat in your house (as my grandfather would say! ) In this day and age, we all have to be conscious of how we use energy, and this is one of those places we all must consider and cut back.

Well, when it's 100 degrees outside and 90%+ humidity, turning the A/C down to 78 isn't going to do much. People DIE from heat in these parts. And because of the super-high humidity, mold and mildew grow before your eyes if you keep the house too hot.

 

[cruisnfamily]

Well, when it's 100 degrees outside and 90%+ humidity, turning the A/C down to 78 isn't going to do much. People DIE from heat in these parts. And because of the super-high humidity, mold and mildew grow before your eyes if you keep the house too hot.

What do you mean? I live in SW FL and I keep my air at 78 much of the time...never any lower. It certainly "does do much" as far as I'm concerned. Our house is always comfortable. Nobody's going to DIE from heat if their a/c is set at 78.

 

[Muushka]

Okay, with all due respect, this is the budget board! Who is keeping their a/c in the low 70's? If you want to save money, stop turning it up and down and just keep it at at least 78. Ours stays at 79-80, and I find that very comfortable with the lack of humidity. The point of air conditioning is to make the heat comfortable, not be able to hang meat in your house (as my grandfather would say! ) In this day and age, we all have to be conscious of how we use energy, and this is one of those places we all must consider and cut back.

I'm with you and cruisnfamily. In fact, ours stays at 80 during the day and when my husband comes home I 'splurge' and put it down to 78 or 79! Ceiling fans do wonders.

 

[sarahkaiserdse]

Everyone has a comfort level. You should set your thermostate there and see what happens. At my house we have a seperate unit for the main floor and the second floor. We have a large two story house and this is what works the best for us. I keep both of my thermostate at 70 degrees year round weather it is hot or cold. I live in Michigan and honestly our gas and electric bill has never been out of control. Of course we do lots of maintence to help the house keep the heat or the air but my bills are lower then the home next door which is similar in size to mine. The only reason I know this is because just yesterday she came over all upset because she does not know how we can afford to run our a/c because theirs are so high...... She is a nosey busy body but thats another post.

I work in a quilt shop and in the summer they always turn the A/C way up like 88 at 5 on Sat. It does not come back on until Tue morning and the building does not cool down until at least 2 in the afternoon. I bet my boss that if she left the temp alone all the time that the bill would actually be cheaper. I won the bet it went down $20.00. This is a pretty big difference but its a fabric shop with lots of wood and as soon as you stop running the A/C the humidity just soaks into the fabric and wood and has so much trouble cathing back up.

Just my 2 cents the only person who really benifits from turning down or up the temp during the day is the electric company they have less of a draw on the system.

 

[cruisnfamily]

I got the following quote off the FPL website:

Cool your home only when you're there. When you leave for the day, move the thermostat up to 82 and turn it back down to 78 when you come back. It costs a lot less to bring the temperature down to 78 than it does to keep it at 78 all day. You can even buy an inexpensive programmable thermostat that will do this for you automatically, so your home will be nice and cool whenever you're there...and you won't be wasting money when you're not.

So I go with their theory. I figure they know more than I do. Our home goes up to 84 when we're not home...down to 78 for later afternoon and evening...up to 80 for while we sleep.

 

[Oldironsides]

I have a raised ranch and the second level really holds the heat. Last summer we put some thermal curtains on the upstairs windows and sliding glass door. We closed them when we were gone for the day and it made a huge difference. It also helped with the heating in winter. New energy saving windows will also make a huge difference.

 

[sarahkaiserdse]

"I got the following quote off the FPL website:

Cool your home only when you're there. When you leave for the day, move the thermostat up to 82 and turn it back down to 78 when you come back. It costs a lot less to bring the temperature down to 78 than it does to keep it at 78 all day. You can even buy an inexpensive programmable thermostat that will do this for you automatically, so your home will be nice and cool whenever you're there...and you won't be wasting money when you're not.

So I go with their theory. I figure they know more than I do. Our home goes up to 84 when we're not home...down to 78 for later afternoon and evening...up to 80 for while we sleep"

As I stated in my previous post the only person this helps out is the electric company which is what FPL is. Ask any licensed HVAC person and they will tell you that is incorrect. But alot of people belive this and to be honest it sells more A/C units and furnaces for me so who am I to disagree.
To each their own.

 

[delmar411]

wow, I must be hot blooded or something because I couldn't live in a house that was 80 degrees! Our thermostat lives at 68 degrees, 24/7 365, and I'm sweating still a lot of the time, while DH and the kids are bundled under blankets.

Anyway we have really reasonable electric bills IMO. I pay around $100 in the summer when the A/C is going non-stop and around $50-60 in the winter.

 

[kellia]

Uh oh, here come the temperature wars again! It really depends on where you live, humidity, where your thermastat is located, what brand of thermastat you have, how good the insulation/windows in your house are, ranch/2 story/basements, etc, all make a huge difference as to what a certain temp feel like. 70 degrees in one house might not be 70 degrees in another.

 

[cruisnfamily]

Uh oh, here come the temperature wars again! It really depends on where you live, humidity, where your thermastat is located, what brand of thermastat you have, how good the insulation/windows in your house are, ranch/2 story/basements, etc, all make a huge difference as to what a certain temp feel like. 70 degrees in one house might not be 70 degrees in another.

I wasn't looking for a war. I was just trying to answer the OPs question which was "does it save money to turn the thermostat up when nobody is home" I believe it does save money to do so.

Some of you choose to believe the power company is lying when they make a statement on their website to that affect. That's ok, you guys pay your power bill, I'll pay mine and I'm going to assume they're stating fact not fiction.

Does anybody know what a reliable source of this info would be? If not the power company, then who would we go to to get the answer to this question?

 

[firsttimer2007]

A good question was asked at the beginning of this board but has not been answered. So I am hijacking someone elses question -- I would love to know the answer.

If you leave for a week, or more or less, would you save money turning the temp up or even the a/c off?

How long would you have to leave the a/c turned up/off to notice a diffrence on the a/c bill?

 

[cruisnfamily]

Consumer reports says: Your first step is to run your air conditioner(s) less frequently. "If you're working eight hours a day, why air-condition your house while you're away?" says Christina Kielich, a spokeswoman for the DOE. You can reduce your annual energy bills by about 10 percent by turning up your programmable thermostat 10º to 15º F when you're out of the house, says the DOE. Upon returning home, Kielich says, "Pick a temperature that's comfortable and stick with it."


Ask Mr Electricity says: It's a myth that leaving the AC on while you're away at work uses less energy than turning it on when you get home. Here's why:

Heat goes to where it's not. With the AC off, your house will absorb heat from outside, but at some point it will be so hot it can't absorb any more heat. When you come home and turn the AC on, the AC has to remove the accumulated heat only once.

But if the AC is on when you're gone, then your house is constantly absorbing heat because your AC is constantly cooling down the house. The AC has basically turned your house into a heat magnet. So your AC is removing absorbed heat over and over and over again.

Let's say you leave the AC off, and your house absorbs 20k BTU's of heat and then stops, because that's all it can absorb.

Now let's say that you have the AC running instead. The house absorbs 5k BTU's of heat, so the AC kicks in and removes it. Then it absorbs another 5k BTU's, and your AC kicks in and removes that. Repeat that process several times during the day.

This is not a gray area, and there's no question about it: running the AC when you're not home wastes energy, period.


Energy Boomer says this: Air conditioners are to cool people not homes. Shut it off when there is no one there to enjoy it.

Heat always moves toward cooler temperatures. The cooler your house is the more heat will push its way in. With the air conditioner off, the house will warm up and the flow of incoming heat will slow down. It is self-limiting.

If you leave the AC on and keep the house cool, heat will keep flowing in. This keeps the AC working hard to keep the temperature down and make the electric meter spin faster.

 

[estherhead]

I don't want to start a war, and in theory I understand these articles & this feeling, and the engineering sense behind it. And it is about how long you will be gone, how good the insulation is in your house, where you live, etc.

But in practice, our little business often disagrees with engineers. Don't even get me started. Their minds think in straight lines (sorry, I know I'm starting fights with all the engineers) and reality just doesn't seem to follow straight lines always. In the heat of the summer, day after day, we in the HVAC business have people call us & complain that their AC isn't working. They say it is running all the time & the house doesn't get cool & their electric bills are huge. When in fact they are turning it completely off while they are gone & letting their house get to 90+ and then trying to cool it when they come home. It never can recover & therefore runs all the time & doesn't cool. So Friday night they turn it on & are home all weekend & it "works" on weekends.

If I were going on vacation, I would turn my AC off. Obviously, this would save money. But here in the humidity of Ohio, with our customers, it is cheaper to lower it 5-10 degrees while you are gone & no more. If you do more it will run constantly when you get home & never come to back to a comfortable temperature. Which means you are spending A LOT of money to sit in a house that is hot. To me, that is a waste.

I do think everyone has agreed on one things. Programmable t'stats are good things. No matter what your preference to set them at, you will be more comfortable, more of the time, for less money with a programmable thermostat.

 

[sarahkaiserdse]

None of the people you are quoteing no anything about your A/C unit. Why don't you try asking a professional oh wait the original poster was answered by a professional you still want to argue. As I stated before you should do what ever you want to do. When people do what the electric company tells them to do it creates more work for me and many other HVAC companies so for that I am thankful. Turning your unit up and down creates alot more stress on your unit which means it costs more money to run it and it means more service calls to our company. If you had any working knowledge of how they were designed and put together you would understand that you are not really saving unless you have a home that has no insulation drafty windows and you leave every light on in your house when you are gone.
As I stated in my original post. As an HVAC company owner you are only turning your t-stat up or down a few degrees its not going to matter but if you turn your a/c completly off or close to your are losing any savings. Becasue you A/C will have to redehumidify your house over and over again. Which is not cost effective to you or to your unit.
I hope everyone stays cool regardless of what you believe.

 

[kellia]

I wasn't looking for a war. I was just trying to answer the OPs question which was "does it save money to turn the thermostat up when nobody is home" I believe it does save money to do so.

Some of you choose to believe the power company is lying when they make a statement on their website to that affect. That's ok, you guys pay your power bill, I'll pay mine and I'm going to assume they're stating fact not fiction.

Does anybody know what a reliable source of this info would be? If not the power company, then who would we go to to get the answer to this question?

Sorry, that wasn't what I meant. I think this thread has a lot of very good information on it! I was referring to when people start criticizing because others have their heat/ac set at a different temperature than theirs. I was just trying to say that just because their thermostat says it is a certain temp in their house where they feel comfortable doesn't mean that other thermostats in other houses would show the same temperature reading.

 

[englishrose47]

According to information ont he DOE website, you should turn off window ac units when you wil be away for a few hours, but raise the temp for central air units.

We have window units , so they should be turned off during the day? Dsil insists they need to be on !! Experts pleas help!!

 

[cruisnfamily]

Why don't you try asking a professional oh wait the original poster was answered by a professional you still want to argue.

I don't want to argue. I guess I'm saying I want to see facts that substantiate those claims....not just one guy's opinion. Just because somebody works in a particular business and has an opinion doesn't make them right. I happen to disagree based on reading and research I've done on the subject. If there are supporting facts in writing somewhere I'd be interested in checking them out. In addition I think it's beyond silly to assume that a company like FPL is going to put an out and out lie on their website in order to convince us all to do something wrong so they can make more money. Don't you think that one of your "experts" would call them on it if they were really lying. Imagine the public outcry! I just don't believe they would do that. But maybe I'm just uninformed.

I'm fine with everybody believing what they want and setting their A/C however they want, I was just trying to answer the OPs question to the best of my ability.

When we leave for the day, we don't turn our A/C off, we raise the temp by about 6 or 8 degrees which according to what I've read will save us money. When we leave town, we also don't turn the unit off, we'll just set it about 10 degrees above normal in an effort to also save money. This is how we'll continue to play it at our place and hopefully it is the correct way to handle it.

 

[summerrluvv]

I haven't read the entire thread, but I can tell you IME with our A/C..if it's off all day, I come home and it's close to 80 degrees upstairs. I turn it on and it will run for 12 hours before it's actually down to 72 or so. OR I can turn it on, keep it at 72 all day and it won't be running for 12 hours straight.