This paper describes adaptive lifestyle in summer with the retrofitted double-sash windows, blinds attached between the windows in an existing apartment building in Hokkaido. An occupant with retrofitted double-sash windows opened and closed the windows in eight different ways, including opening the exterior windows during the day, using blinds between the windows to shield sunlight, and closing the interior windows whether or not air conditioning is worked. An occupant with unimproved windows opened both exterior and interior windows for ventilation, or closed both windows when the air conditioner was running.
