This post discusses the style of the most energy efficient windows you can buy. What I am referring to is Casements/awnings and picture windows. Due to air infiltration being a big part of the overall thermal efficiency of a window, these window styles win out, hands down. Of course Picture windows would be the ideal situation for all your windows since the air infiltration on those is virtually zero. But, obviously not many people want no possibility of ventilating in their home. BUT, If you mix these with some critically placed casements and awnings, you can build the perfect choice for the best return on your investment, ESPECIALLY if you are in a high wind area. The second train of thought is to use these types of windows on certain sides of your house that get the higher winds.