I have a small combination microwave/convection oven mounted above the range top. I also have a normal sized conventional oven. Both ovens are heated by electricity. During the winter I don’t care about efficiency because any lost heat goes into my house, but during the summer when I have to pay for the energy twice, once to heat and then again to transport the heat outdoors I do.
Because the conventional oven is larger, it takes more electricity to heat, but it also has better insulation than the smaller convection oven. I try to use the convection oven when I have something to pop in the oven for a short time. Has anyone ever conducted an exercise to determine what the break even time is when I should use the conventional?