Is it worth it to turn the ac off during the day?

[crunchy_mama]

Since dh is now working days I have been keeping the air off during the day and keeping fans on and then turning on the air about 7 pm - to 71-73. Is it worth it when the unit has to work harder to get the house down , instead of maintaining. Today the house is up to 84 and we haven't got up to the hottest weather yet. I would like to think that having the air off for half the day is helping, but dh thinks otherwise- of course he hates the heat.

[1growingsprout]

In our home NO, alot depends on your sun exposure, the size and efficiency of your unit. If i was you, i would turn the air up to 78-80 during the day then down when DH comes home.

We found the 2x daily off/on costs more then just keeping it on straight through.

[library lady]

Nope, it isn't worth it. We live in hot Texas and we tried turning the AC off during the day but it proved to be more expensive than if we just turned it up to about 80 during the day and then only turned it down to about 75 in the evenings. We can program ours so we set it to gradually go down so that it would get some breaks in between times. We have it set to go down to about 78 around dinner time and then down to 76 just before bed time.

[Oonah]

I looked into this a while ago and found this....
Ask Mr. Electricity


he has an interesting response to the question....

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.

[jennlyn]

I would not turn off the ac completely, as it is inefficient to let the whole house heat up, then try to cool it all again. Reason being is that everything in your house gets heated up and all of it needs to cool down again. I don't understand why you would want to turn it off completely , then turn it down to 71-73. Just turn the thermostat up during the day to whatever is tolerable to you. I've found that we can do about 82-83 and it isn't horrible. Maybe a bit less when it is very humid, but I don't turn it down to less than 80. If you are acclimated to the warmer house, you'll find that anything cooler feels cold. If you find that it is cooler in the morning/evening, open up your windows and doors and let the cool air in for a bit. Keep your shades closed and if you have curtains over them, pull the curtains to help keep the house cool.

[gbutterflykissesm]

I've always wondered about this too, and haven't really tested it both ways in my own house to see which is better, but I do have a comment about the fans. I read once that fans don't actually cool air, they cool people. They circulate air, of course, but the reason humans feel cool with a fan on is because when the moving air hits the skin, the moisture evaporates, leading to a cooling effect. So if you leave the fans on when you're not home, it is actually not helping to keep the house cool at all. (It might circulate the air and maybe get the hotter air out of a particular room that absorbs it more and distribute it better, though... not sure about that). Also, as an aside, I guess fans don't really work to keep dogs cool then... I always wondered about that

[Christine&men]

Originally Posted by jennlyn

I would not turn off the ac completely, as it is inefficient to let the whole house heat up, then try to cool it all again. Reason being is that everything in your house gets heated up and all of it needs to cool down again. I don't understand why you would want to turn it off completely , then turn it down to 71-73. Just turn the thermostat up during the day to whatever is tolerable to you. I've found that we can do about 82-83 and it isn't horrible. Maybe a bit less when it is very humid, but I don't turn it down to less than 80. If you are acclimated to the warmer house, you'll find that anything cooler feels cold. If you find that it is cooler in the morning/evening, open up your windows and doors and let the cool air in for a bit. Keep your shades closed and if you have curtains over them, pull the curtains to help keep the house cool.

I second that!

[elizawill]

we don't use the ac in the day and for us it is worth it - but i don't turn it as low as you do at night. i open all of our windows and turn on ceiling fans in the daytime. it is hot already in SC, so in mid summer i don't know that i will be able to do this. at night (about 7:30) i turn the air to about 74 to cool down the house, but after 30 minutes or so, i put it back up to 78 or 79 and it feels very comfortable. when i wake up in the morning - i cut it off.

we're cutting back on every single possible expense though to get out of debt, so this is the only reason we are doing this. but it does make a difference in our bills by a lot.

[Sarah W]

Instead of turning it off, you can get a programmable thermostat. (maybe $40 at Home Depot). However, what we found was that it we turned it off during the day and back on in the afternoon, it cost more money. However, if you keep your house at a higher temp (80 or so) then go back down, it's more efficient.

[lmbjer]

Our house is about 1000 sq ft, one level, and a slab. It is very efficient for us to leave the air off during the day and turn it on in the evening. We are fortunate for that.