The single hung window has a bottom panel (known as a sash) that moves vertically (up and down), and an upper panel that remains stationary. When the window is wide open, the bottom panel covers over the upper panel.
Single hung windows are the usually the standard option for new homes, renovation projects, and retrofits. Single hung windows are the most basic window available, and therefore the most economical in terms of price. All are Energy Star® certified for energy efficiency.