A window has an inner sash and outer sash that are removable from the frame. A pivotal step is located along an outer surface of the inner sash. For a double-hung window, there are two pivotal steps, one along each side of the outer surface of the inner sash. For a horizontal slider window, there is one pivotal step along a top of the outer surface of the inner sash. When the inner sash is tilted inward or removed from the frame, the pivotal step can be rotated inward to allow the outer sash to be tilted inward or removed. When the pivotal step is in an operating position in the window, it greatly reduces the air flow from an exterior of the window to an interior of the window around the sashes. With previous windows, there is no step immediately adjacent to an outer surface of the inner sash or, if there is such a step, the presence of the step makes the removal of the sashes cumbersome.