The Water Demand Calculator (WDC) was developed in 2018 to estimate peak water demand for pipe sizing purposes in residential buildings with efficient fixtures–an update to Hunter's 1940 Curve. The WDC is widely accepted and adopted for use in various states and municipalities. The methods in the WDC are suitable for any building provided the parameter – probability that a fixture is busy – is known. This presentation is an overview of the ongoing research efforts to extend the functions of the WDC to commercial and institutional buildings. A non-intrusive wireless sensor network was developed to address the pressing need to estimate fixture probability values in different building types. The wireless sensor logs flow readings every second, continuously indicating when water is flowing in the pipe to a fixture. It has been tested, validated, and deployed to collect data to determine fixture probability of use. The analyzed data shows subtle differences between similar fixtures in buildings with different end uses. These fixture p-values are the necessary update for the WDC, thus extending its use beyond residential buildings. Incorporating fixture p-values for commercial and institutional buildings into the WDC will address issues with oversizing plumbing systems, savings in both water and energy, and complete the modification to Hunter's curve.
