A window assembly having a window frame and at least one primary sash mounted in the window frame. The primary sash has a plurality of sash members forming a primary sash perimeter and a first glazing panel mounted in the primary sash perimeter. At least one secondary sash is pivotally attached directly to the primary sash perimeter along an interior surface thereof so that the secondary sash is rotatably movable between a closed position and an open position relative to the primary sash. The secondary sash has a plurality of secondary sash members forming a secondary sash structure and a second glazing panel mounted in the secondary sash perimeter. An air chamber is located between the primary sash and the secondary sash that is substantially closed to the interior of the building structure. At least one accessory channel is locating along at least one side of the secondary sash members.