Ahh, summer. It's lovely, isn't it? Well, at least until the heat waves and sunburns start to kick in. Then you can find me on my bed wishing I lived about 30 degrees of latitude north.
What can I say? I'm a rainy-weather girl at heart. I also didn't grow up with air conditioning, so I'm no stranger to having to crash out in the cool room underneath a fan. I just had air conditioning installed for the first time, so I decided to take a look around and see what ways existed to keep the C02 footprint down.
The first one was the biggest, really: don't leave the AC on if you're not home. It won't save you any energy, C02, or anything to re-cool your house when you get home.
The second involved no AC unit at all. Don't leave a fan on if you're not in the room, since the cooling effect comes from people feeling the draft. And be sure to switch it in the summer so it turns counter-clockwise, pushing air down instead of pulling it up.
Third wasn't mentioned, but is common sense: don't turn the AC up higher than you need to. Keep it low, and for one of those days where it tops 90 or 100 and you can barely move for the heat. If you can, attic fans will drastically drop the temperature of a house, and they can be solar powered, too. Then you might not even need AC except occasionally.