Don’t use an oven in the summer. It heats up the house, so now you pay more on air conditioning as well. Use the barbecue instead, or do all of your cooking and baking at the same time (early in the morning, or late at night, but no during the heat of the day). In the summer eat more cold salads and cold sandwhichs; avoid meals that require heating.
Here’s a bonus tip: use your barbecue to make pizza! Everyone loves pizza, but if you have a family it gets expensive ordering pizza every week. So make your own. Buy a pizza stone and a bread maker. Before you leave for work in the morning but the ingredients for the dough in the bread maker. When you get home from work the dough will be ready. Spread it out on your pizza stone, and add the toppings, and then cook it on the barbecue. (After the barbecue is warm, ten minutes is about right).
You get to eat gourmet pizza; everyone gets the toppings they want on their section of the pizza, and the total cost is less than a third of what you pay for delivery.