Abstract Submission: In an extensive study to update the methodology of determining indoor pipe sizes, statistical methods and the Water Demand Calculator® (WDC) were developed to estimate the expected peak water demand. Three key parameters are necessary to estimate peak water demand: the number of fixtures (n), the fixture flow rate (q), and the probability that a fixture is in use (p). The probability of fixture use (i.e., fixture p-value) is the ratio of the duration of flow at a fixture to the observation window. The observation window is the peak period of water use in a building. Fixture p-values for six fixture types in residential buildings were estimated from a database of water use events at individual fixtures in over 1000 residential homes, thus limiting the WDC to single-family and multi-family residential buildings. The recognized benefits of the WDC for residential buildings underscore the importance of extending it to all commercial, industrial, and institutional building end uses. Acquiring data in the format collected in residential buildings is expensive, difficult to collect, and not readily available, especially for large buildings with many fixtures. To extend the use of the WDC to nonresidential buildings, the fixture p-values would need to be estimated from readily available data—flow data from the service line into a building, or from a branch supply to multiple fixtures. This work details how data collected from the combined flow from multiple fixtures can be used to estimate fixture p-values in nonresidential buildings by using the methods in the WDC, assuming a fixture worst-case scenario for use and determining the building utilization factor.
