We have developed the dynamic estimation method for cold and hot water supply demands based on the data of water usage in the time series through a day by using a personal computer. In this paper, we set up the calculation models for toilets bowls, wash basins in the toilets, hot water service rooms of an office building based on the past papers. The loads of cold and hot water consumption are estimated by using dynamic calculation method (MSWC program). And we compared the calculated value with the measured value.