IMPACT ON PEAK FLOW WHITEPAPER
Increase in Flow Diversity From Simultaneous Fixture Use
In calculating peak water demand, there can be instances where an increase in fixture count results in a decrease in the expected peak demand. This white paper explains why this counterintuitive result can occur, especially when there is some probability of stagnation (i.e., zero demand). Using IAPMO’s Water Demand Calculator (WDC), we are not designing with zero flow in mind; hence, zero flows are ignored, and the 99th percentile is extracted from actual flows for any combination of busy fixtures.
- The current Water Demand CalculatorTM has three methods of estimating peak demand. WDC version 2.1 has Exhaustive Enumeration (EE), Modified Wistort’s Method (MWM), and Wistort’s Method (WM), while in the WDC version 2.2, Convolution process replaces EE.
- Each method estimates peak demand transitioning from small buildings with few fixtures to midsize and very large buildings.
- Each method requires three key fixture parameters to evaluate the peak water demand.