Does keeping the air conditioning on at a preset level save energy and money?

Question

My wife and I live in a hot area in Southern California. A friend has told us that if we keep the air conditioning turned on at a preset level that it will cool to that level and then only turn on to maintain that level of coolness instead of working hard to cool an already overly warm house. This will reduce costs in the long run as it would take less energy to keep a house at an already predetermined temperature. Is this so?

Answer 1

What you are talking about is more economical than turning A/C on to cool your house, then turning it off completely while you are not there during the day, or away for a weekend, then turning it on again when you return.
However, setting back the temperature during unoccupied periods is a major energy saver. For example, if you keep the house at 78 (deg.F) in the evenings and at night time, and then let it rise to 85 while you are at work during the day, a properly-sized A/C system should be able to cool the house to 78 quite quickly when you get home. The cost to cool the house down from 85 to 78 will be far less than what you will save from running the A/C less for the 8-10 hours you are out of the house. Depending on preference, and especially with a programmable thermostat, many people will save even more energy by bumping the temperature setpoint up a few degrees while they are sleeping as well.
Keeping the house at the same temperature all of the time is certainly easy, but is also a great way to get rid of all that pesky money!
Of course the same principles apply in winter (especially up here in northern Canada) in reverse!

Answer 2

The issue you are fighting is the thermal mass.. If you turn it off and you live in a hot area, the ac has to work harder and longer to cool everything back down so you spend more money and more wear and tear.
The best thing to do (and this requires some experimentation on your part) is to get a programmable thermostat and have it cut the cooling back to let it get say 5-7 degrees warmer than you like during the day and then have it kick back up about 30 mins before you get home in the evening.

The key is finding the right mix and that will be specific to your coolness desire, the house insulation and the region you live in.
Note this can be done with heating in the winter and works well if done at night while you are snuggled in the blankets.. have the heat drop 30 mins after bed time and ramp up 30 mins before time to get up..

Answer 3

It depends on how well insulated your house is and the humidity level. As an A/C contractor with a newly built home I set my T-stat at 77 deg. F while I am at work and preset to drop down in stages to 74 then 72 at night. If your house has poor insulation and old windows that are drafty your unit could run for hours and not ever catch back up.

Answer 4

I answered this question earlier today for someone in Vegas and I agree.
However, there was a suggestion of getting a programable thermostat. This seems to make a lot of sense. You could have the unit shut off (assuming there are no pets that might suffer) and have the thermostat turn it back on an hour or two before you get home. I am definately going to try this myself. Good luck.

Answer 5

Sure is. I live in Scottsdale, AZ- where it was 110 today & we keep the thermostat set at 76 degrees all Summer. I ALSO pay the Electric Bill every month- & there's NO DOUBT that keeping it set at ONE temperature all the time (& the HIGHER you can stand it- the better) saves money & elecricity. Listen to your friend- he sounds like a "keeper". :)

Answer 6

Yes it does 78 or higher is a good seting with ceiling fans and when you leave turn it up a little higher