One of the factors to influence the indoor air quality is dweller's habit of operating windows. An instrument to measure the open-width of sliding window was developed and the open-widths were measured in six detached houses through a year. The results are the followings.
1. The open-width depends on the daily dweller's schedule and the indoor temperature.
2. The open-width increases with the indoor temperature, but the time length of wind opening is short in the room with cooler.
3. In the room which temperature is high, the room is cooled more frequently and the open-width becomes large when the window opens.
