A study for the fire safety planning of the Himeji-jo castle, main tower

Himeji Castle (Himeji-jo) is a Japanese National Treasure and an UNESCO World Cultural Heritage site. The castle is visited by a large number of visitors, around one million every year and a maximum of 9,000 in one day. Experiments on a 1/25 scale model are carried out to grasp the feature of smoke movement within the main tower, so as to improve life safety and mitigate damage to the building in case of a fire. The Froude number is considered for similarity, and the movement of smoke is visualized. The experiments demonstrate certain interesting effects resulting from the architectural features of the castle; in particular, deep soffits on the lower stairs, along with tall windows, which are generally left open during the day, can significantly reduce the risk of smoke penetration to the upper-level stairs. The tests produced detailed data on the distribution of smoke in different fire scenarios, particularly the zones that are unaffected and inundated by smoke. Integration of these results with the evacuation characteristics of the building will be an essential part of functional safety planning for the castle.