If your house is chilly on a cool spring or summer morning/day, instead of turning on the heat for a half hour or hour, bake or cook something to warm up the house. Use that day to cook large meals for freezing or bake that healthier recipe you've been wanting to try. Multi-tasking at its best - warm up a chilly house, get some cooking done without cranking up the a/c, and if it is cool outside, once the house warms up, open the windows to air out the house!
Using cool days to do large cooking/baking projects will save money. When the weather forecast shows a temperature drop coming, plan to use that day to your advantage. You can also open the kitchen windows overnight and start the day bundled up until it warms up from the heat of the oven/stove.