When installed in combination with older, less efficient windows, storm windows enhance efficiency by creating another barrier between the interior of you home and the weather outside. However, ENERGY STAR qualified windows
are designed with multiple panes of glass and specialty gas fills, which create an even more effective barrier within the window itself. ENERGY STAR qualified windows also have additional features such as low-emittance (low-E) coatings and high performance frames that enhance efficiency even more. With these features, storm windows are not generally necessary in order to achieve a high level of energy efficiency.