Chapters 5 & 6 of the "Low Carbon Diet" discuss the things you can do to use less energy when heating and cooling your home.

1. In winter time, set the temperature between 65-68 degrees when people are home, and 55-58 degrees at night when people are sleeping or away from the house.

Commentary. Personally, I find 55 degrees at night to be too cold. We'll try 60 degrees this winter.

2. Install a programmable thermostat.
We will do this before winter. We have one at work, and it is great - we set it to automatically turn the heat up and down during the week, and to keep it down on the weekend when no one is there. It is easy to over-ride for special occasions when people are in the office late or on the weekend.

3. Install an EnergyStar A/C unit and keep the air filter clean.

4. Install your A/C unit so it is in the shade! This will increase efficiency by 5-10%!

5. Raise your thermostat by 4 degrees - 78 degrees should be plenty cool.

6. Plants trees and use window shades to keep the sun from beating into the house!

7. Install an attic fan to keep heat from building up in the attic. I added this one to the list. We have an attic fan that snaps on automatically when the temperature in the attic reaches a pre-set level.

8. Only use the A/C when you need it! This is another one I am adding. A relative told me once that he has his A/C from April until the furnace goes on in the fall. No open windows! Never!

Our A/C system consists of two window units - one upstairs and one downstairs. We rarely use the A/C, and are able to stay comfortable most days with just ceiling fans and a couple of oscillating fans. Even when it is hot enough for the A/C, by the time we go to bed, we open the windows and turn the ceiling fan on instead because we'd rather listen to the crickets than to the window A/C unit in our bedroom.

One of the main reasons our house does not become uncomforatble even on hot days is the number and location of large trees around the house. In particular, there are two bur oaks to the southwest of the house that pretty effectively block the sun in the hottest part of the day. In addition, the house (which is 100 years old next year) has deep eaves that keep most of the windows in shade for much of the day.

So, if you do all the things on the list, it looks like you can cut your heating-cooling related CO2 by about 2,000 pounds a year. Not bad.