Your options for wall ovens include:
Conventional ovens rely mainly on electromagnetic waves that radiate from the oven's sides. The air moves throughout the oven by natural convection-the warmed air rises and is replaced by cooler air, which then rises and is replaced, and so on.
A less expensive option.
Because the heating source used for baking is located on the bottom, it can be tricky to get food on the top and bottom shelves to cook at the same speed. There is a heat source at the top of the oven, but it's used for broiling. You may want to get a model that allows you to cycle the bottom heating element on and off.