Both lower and upper sashes can move up or down.

This term describes windows that are raised and lowered rather than cranked open. "Double hung" refers to the system of counter weights on either side of the window housing which attach to the bottom pane and prevent it from closing when opened. Once discarded in favor of crank-opened casement windows, double hung windows (new varieties are much better insulated and energy efficient) are regaining popularity in today's homes. Double hung windows feature screens on the outside.

WINDOWS WITH AN OPERABLE UPPER AND LOWER SASH, EACH SUPPORTED BY CORDS AND WEIGHTS, SPRINGS, OR TENSION PROVIDED BY STOP MOULDING. IN SINGLE HUNG WINDOWS THE TOP SASH ISN'T OPERABLE.

A window where both the top and bottom section of the window moves up and down.