According to a study conducted by the Lawrence Berkeley National Laboratory, the energy lost through inefficient, aging,  residential windows accounts for 2% of total U.S energy consumption, and 9% of total U.S. residential energy consumption. Because energy efficiency is a crucial part of sustainable design, energy efficient windows can greatly impact the environmental  performance of a home or building. 

High performance windows can be a bit more expensive up front, but long term operating costs related to heating and cooling your home will be reduced. You will also experience greater comfort during  hot summer or cold winter months. In addition, high performance windows cut noise and UV light. This results in less fading of window treatments, furniture, and the like. 

High performance windows ar those that combine multiple glazings, Krypton glass interior, low E-coatings, as well as tight seals and insulated frames.