With modern convection or fan ovens, preheating is usually not necessary. This does not detract from the quality of the food, but it does save a lot of energy. For example, if you preheat for twelve minutes every 200 days of the year, it will cost you a whopping 31 euros. If you are still using an older oven, preheating is only necessary for delicate dough dishes, such as sponge cake or pizza dough.

And if there are several dishes at once: Convection is the best way to utilize the different levels of the oven. The same applies to the oven as to the lid on the pan: save yourself and your food extensive inspection and tasting tours. Every time the oven door is opened, cold air enters and needs to be reheated.