Single and double hung windows are often compared due to their similar appearance.  Both windows are durable, customizable, versatile and relatively easy to clean. These factors, combined with their cost efficiency, have made them some of the most commonly used windows in the nation. 

However, there are some sizable differences when it comes to the functionality and efficiency of the two.  On a single hung window, only the lower part of the window slides to open, while the top remains fixed in place.  On a double hung window, there are two operating sashes that allow for air ventilation.  The single operable sash in a single hung window is the one that tilts in for cleaning, while both sashes can be cleaned in a double hung. Some of the main differences between single and double hung windows also come in the form of energy efficiency. The fact that double hung windows have two sashes instead of one provides a homeowner with increased control over ventilation and airflow. While the U.S. Department of Energy reports that homeowners can expect to save dollars every month on energy bills by simply replacing their outdated single hung windows with new double hung ones.