Modelling of water demand in building supply systems using fuzzy logic

This paper presents a method to establish the design flow rate adopting probabilistic and possibilistic approaches to model the subjective behaviour of the users that affects strongly the duration of usage of sanitary appliances. At first, the Monte Carlo method is used to determine the instance of usage of the sanitary appliances. After that, fuzzy logic is applied to determine the duration of the shower. As a result, historical records of the use of the sanitary appliances and the flow rate during the peak period can be generated. The design flow rate obtained by the simulation is about 23% lower than that assessed by the Brazilian standard, based on deterministic approach, and closer to the values calculated by the probabilistic model. Practical application: As the processing cost is extremely low, the simulation based on the proposed method is also an efficient means to obtain a quite accurate estimate of the flow rate for the sizing of water supply systems and water meters in water sub-metering systems.