Models for Generating Household Water Demand Pulses: Literature Review and Comparison

In the context of household water demand generation with high time resolution (down to 1 s), two different categories of models have been proposed, aimed at representing instantaneous demand as the superimposition of pulses with constant intensity. The two categories differ in the spatial scale considered for demand generation. In detail, the models of the first category generate the demand as a whole at the household spatial scale. Those of the second category instead generate the demand at the scale of the microcomponents—that is, the various fixtures producing water demand pulses—and sum the microcontributions to obtain the total instantaneous demand of the household. The models of the first category are parameterized based on demand measurements. The models of the second category (actually, only one model exists, named SIMDEUM, standing for SIMulation of water Demand, an End-Use Model) are instead parameterized as a function of information derived from surveys, such as household occupants’ age and behavior, number and kind of household fixtures. This paper presents a review of the models for water demand pulse generation. In this review, the main differences in the modeling structure are described and the various parameterization methods are presented. Though the two categories of model operate at different spatial scales, three models—that is, two models of the first category, Poisson rectangular pulse (PRP) and PRP with correlated pulse durations and intensities (cor-PRP), and model SIMDEUM for the second category—are chosen as representative and are applied to a case study in Milford, Ohio, for which demand measurements and information about the household fixtures and occupants are all available. The merits and limits of the models are highlighted in the applications.