Adjust central AC temperature during the day?

[testinz]

I am wondering if it's better to leave the temperature to always at the specific temperature (eg.: 23) or should I let it go higher during the day when I am not at home (eg.: 26)?

Which way is more efficient?

[MacGyver]

Setting back the temperature (higher in the summer and lower in the winter) saves energy.

[Civuck]

So out of curiosity, what does everyone have their thermostats programmed for?

We are set for 22 Celsius during morning, late afternoon, evenings and 25 overnight, late morning and early afternoon.

[Pete_Coach]

I set it at 23 for when we get up, it then goes to 28 when we are at work and back down to 23 before we get home and then to 25 for overnight. Works for me.
I do, on occasion, set it at something else and put it on hold for the whole day or two. I do this when we get a particularly hot and humid spell.

[speedyforme]

I have it set at 23 when I am at home and I turn it off when I leave for work; roughly 10 hrs a day.

[TCWeasel]

I have it set at 23 when I am at home and I turn it off when I leave for work; roughly 10 hrs a day.

Setting it higher instead of turning it off is often more efficient, depending on several factors. (time away obviously a big one)

When you turn it back on from having been off, the AC now has to work harder to get the temperature back down to 23 and reducing the humidity.

Proper insulation will also be a big factor. Keeping blinds/curtains closed will reduce the amount of heat being created and closing vents for rooms that really don't need to be as cool as the major living areas will also help (eg: bathroom doesn't need to be as cool as the bedroom). More vents closed on the lower floors will enable more cool air to reach the upper floors. Since cold are descends, some of the cool air will come back.

Central air is not always the more effective way of cooling either. In some cases, separate (window) air conditioners more be more efficient.

[shoppingkart]

I set the tstat 24 during the day and 23 evening and night. Setting your tstat back too far (more than 2C) is not efficient, because the A/C has to work much harder and longer (unless you have an over sized unit)to bring the temp back to your set point. It’s easier and not more expensive to maintain a steady temp.

[teoconca]

You should set it back during the day when you are not home. I set it back to 30 C starting 7:30AM and up to 25 C at 5:30PM.

[Javeman]

Setting it higher instead of turning it off is often more efficient, depending on several factors. (time away obviously a big one)

When you turn it back on from having been off, the AC now has to work harder to get the temperature back down to 23 and reducing the humidity.

Proper insulation will also be a big factor. Keeping blinds/curtains closed will reduce the amount of heat being created and closing vents for rooms that really don't need to be as cool as the major living areas will also help (eg: bathroom doesn't need to be as cool as the bedroom). More vents closed on the lower floors will enable more cool air to reach the upper floors. Since cold are descends, some of the cool air will come back.

Central air is not always the more effective way of cooling either. In some cases, separate (window) air conditioners more be more efficient.


I've heard it can be worse to close vents I guess since all the air in the house is shared, the return air vent will suck in hot air from the room where you closed the vent. I guess if you closed the return air in that room as well it would make sense? Can anyone clarify this?

[GTT1]

I keep it at 26 during the day and from 11.00 to 7.00 at night 28. If I find it to hot I temporarily move it to 25.

You would be surprised how accustomed you can get to a little warmer temp. As long as the AC comes on and takes out the humidity we find 25-26 comfortable.

[Menthol]

I keep it at 26 during the day and from 11.00 to 7.00 at night 28. If I find it to hot I temporarily move it to 25.

You would be surprised how accustomed you can get to a little warmer temp. As long as the AC comes on and takes out the humidity we find 25-26 comfortable.


Same here.

[Cheap Cat]

I never program my thermostat for my AC. I always turn it on and off manually. So far I've used it for about 1 hr this year and that was the other day when the humidity was high. My plan was to not use it at all this year.

We spend the whole winter shut up in the house so it is the last thing I want to do in the summer. I have my windows open and use ceiling fans which make a huge difference as I don't get good airflow in my home. On really hot days, I shut the windows during the day and open them as soon as it starts cooling down at night. I always keep an eye on the outside temperature as well as the inside temperature and humidity. I also keep the curtains shut but open them as soon as the sun isn't beating down on that window. My living room gets the afternoon sun and will be unbearably hot if I don't shut the curtains.

You guys sound like my neighbour who has the AC going all the time. If they just opened the windows, they would see how nice it is outside.

[Javeman]

I wish I could turn the AC off but I have a Siberian Husky that doesn't do too well when it gets warmer so the AC is on almost all day although I keep it at 24C.

[TCWeasel]

I wish I could turn the AC off but I have a Siberian Husky that doesn't do too well when it gets warmer so the AC is on almost all day although I keep it at 24C.

Buy a chest freezer, cut a hole in the side and a pet door on it.

[MacGyver]

It’s easier and not more expensive to maintain a steady temp.Totally false! It is more expensive! That's because of simple laws of thermodynamics. If you are keeping the inside of a building at 24C while it's 30C outside, there is always going to be heat gain from the outside to the inside because of that temperature differential. That heat gain equals energy your air conditioner is consuming. If you stop air conditioning, then the heat gain from the outside to the inside stops, until you restart the air conditioning again. Then the AC only has to condition the volume of inside air to the desired temperature/humidity before the heat gain starts again.

I'm in commercial property management. We don't run the AC during nights and weekends in large buildings with annual electric bills in the seven-digit dollar range, and the inside is perfectly inhabitable on Monday morning after the ventilation systems have run for only a couple of hours.

[gomyone]

I might be the only one who sets his AC at its lowest temperature at night (21C after 10pm). Since the upstairs tends to be about a degree warmer than downstairs, 21 on the mainfloor makes upstairs sleeping conditions more comfortable.

By morning (ie., 6am) the AC goes up to 23, then during the day (after 9 when we are not at home up to 25). In the evening, when we are back at home (6:30) its goes down to 22.