Introduction — what readers searching for the smallest most efficient air conditioner want smallest most efficient air conditioner buyers want maximum cooling from the smallest footprint while paying...

Learn how to choose the most efficient window air conditioner - compare EER, CEER, size, features, installation & maintenance to cut energy use and lower bills.

Find the best window air conditioner for efficient cooling: size by BTU, choose Energy Star, low-noise models, smart features, and installation tips.