I was shocked to learn that opening the oven door whilst cooking or baking lowers the temperature by as much as 25-50 degrees (!) thereby significantly increasing my cooking time. I shudder to think of all the time, energy, and money I wasted with such behavior. Ever since I made this discovery, I’ve been keeping the oven door shut and putting my little oven light to excellent use—huh, so THAT’s what it’s there for. There are plenty of other ways to use the oven efficiently when cooking. For example, Ideal Bite says that they only time you need to preheat the oven is when you are baking cakes or pastries—for any other food you can skip this step. That’s definitely news to me! It also recommends that you turn the oven off a few minutes early to save energy. And Do It Yourself.com recommends using glass or ceramic dishes, which cook food faster at lower temperatures.
How do you save energy in the kitchen?

Do You Open the Oven Door When Cooking  - 23