Wall ovens are available in three widths: 24, 27 and 30 inches. The energy used by a wall oven relates to its size, so it's worth going for a smaller unit if it will meet your needs. If you have the occasional need for more capacity, opt for two smaller ovens rather than one larger unit. You'll save energy by frequently using just one of the smaller ovens, and for large gatherings you'll still have all the capacity you need.
Seek a model with a convection oven, in which a fan continuously circulates heated air around the food. This means that the temperature and cooking times can be reduced, using 20 percent less energy. Also look for a self-cleaning feature, as these models are better insulated, which boosts energy efficiency by maintaining oven temperatures.
Money- and energy-saving tips:
Save your oven for large or multiple dishes. Ovens are inherently inefficient — only about 6 percent of the energy from a typical oven is absorbed by the food.
Use your oven light to check on food's progress. Every time you open the oven door, the temperature drops 25 to 50 degrees.