Single Hung windows open vertically without consuming much space. They are great options when exterior space is a concern. You do not need to go outside to wash the window. The best places to place them are walkways, porches and patios. Single hung windows are typically the same as double hung windows however with a single hung window design only the bottom sash slides upward. Double hung windows allow for the sashes to slide both upward, and downward. Other than that single hung windows are identical to double hung windows and are widely available in the same sizes and shapes