Could someone with any understanding of airconditioning and conservation answer a question?

[DuaneBidoux]

I live in Houston. As you might imagine, air-conditioning is a fairly important part of making this into a livable location.

I have been completely turning my air conditioner off while I am gone in the day (about 10 hours). Of course when I get home it is very hot inside and I immediately turn it back on. It will crank for a good three hours before it finally gets cool enough to cycle off.

My take is that it takes less energy to cool it back off to the desired temperature than it does to keep it cool while I'm not there.

Does anyone know the answer to this?

[flvegan]

1. I've done the maths

The break even is 12 minutes of a/c time per 60 minutes over the 10 hours you're gone.

I'd always understood that it's easier/better to elevate the temp slightly when gone for a long period then lower it...as opposed to turning it off altogether.

That said, I honestly don't know. I was pretty worthless at math too, so I might have been wrong there.

Congratulations, I've wasted your time I think.

[NJmaverick]

2. There will be a savings by turning it off

Once a house is cooled off the only thing the AC does is make up for heat leadage into the home. The better insulated the home is the less leakage. The other thing that drive heat leakage is the temperature difference. In other words the hotter it is outside compared to inside, the stronger the forces causing the heat leakage. So when you shut off your AC for the day, you allow the temperature to creep upward. This warmer temperature slows down the heat leakage so you save energy compared to running the AC all day. It may seem like it runs for a long time when you get home, but it is still less than if added up all the time it would have run while you were gone.

I hope that makes sense to you.

[LostinVA]

3. It's better to leave the AC on -- it uses less energy/power

Cheaper and greener. Just put it on 80. The same with heat in the winter.