It's worth checking if a model has an Energy Star rating before buying a new oven. These are a good indicator that the oven has been tested to ensure energy efficiency. Single wall ovens unlike freestanding models are mounted at eye-level and have thoughtful extras like a pyrolytic cleaning function. https://ovens-and-hobs-uk21411.theideasblog.com/31407905/what-is-a-built-oven-single