Really Use Oven

If you are cooking something in the oven, try to think of ALL the things you can cook at once, then save some of that stuff as leftovers.

We always put a few potatoes in when we cook, then save them in the fridge for later use. They fry up quickly for breakfast, or are a handy, last minute ingredient. The energy it takes to reheat is so much less than the energy it would have taken to cook them from scratch.

I read somewhere you can put a clean rock in the oven while cooking other stuff, and leave it while the oven cools. Later, take it out, put it in a clean sock, and you have a warm rock for your toes. I've been meaning to try that one, but now that the weather is getting ready to be wonderful, it's hard to think about it.

Don't Preheat

For some things, like breads and pizza, you have to preheat the oven so it cooks the outside with a crispy crust, without baking the softer insides to. But for other stuff, you can put whatever you are cooking right away, and let the cooking begin. No need to preheat the oven.

When your dish is almost finished, turn the oven off and let the dish finish cooking using the heat of the oven. If you leave the door closed, the heat will remain inside for a surprisingly long time.