Abstract:In Japan, there are four methods of calculating water supply demands for office buildings based on SHASE-S 206 and two methods based on the design standard of Ministry of Land, Infrastructure, Transport and Tourism (MLIT). However, these methods were found to produce overestimated values when applied to recent sanitary fixtures with advanced water saving features. To cope with this problem, Murakawa's Simulation for Water Consumption (MSWC), which utilizes the Monte Carlo method to calculate water usage dynamically has been developed. In this study, we evaluated the validity of MSWC on water consumption of an office building. Actual water consumption data were collected from a six story office building. Water consumption estimates calculated by the six conventional methods and MSWC were compared with the actual measurement values. Though the calculations based on the conventional methods significantly deviated from the actual measurement values, those made by MSWC closely resembled them.