Introduction
The behavioural model provides simulation of water use using the Behavioural End-use Stochastic Simulator (BESS) of Thyer et al. (2011). BESS stochastically simulates individual end-uses (outdoor, shower, washing machine, toilet, tap etc) at the household scale at sub-daily time steps using algorithms that probabilistically simulate an individual household’s use of common household water-using appliances. The conceptual framework for BESS as applied in the Urban Developer Plugin, is as follows:
Figure 1. BESS conceptual framework.
For indoor water uses, the water use simulations for each household are based on the type of water-using appliance and the household occupancy of that household. The difference from the average daily model is that instead of specifying an average daily volume and percentages for each end use, the user specifies the water-using appliance and household occupancy and BESS simulates the water for each individual end-use using the in-built parameters for the water use event dynamics. The types of water-using appliances for each end-use are configured in the appliance types. This enables users to simulate the effects of changes in the uptake of water efficient appliances.
The appliances and occupancy for each household can be specified in several different ways, configured under Edit>>Urban Developer Options:
- Fixed appliances and occupancy – where the type of appliances and occupancy for each house are fixed by the user
- Sampled appliances and occupancy – where the users inputs probability distributions for the occupancy and water-using appliance. At the start of Urban Developer run the occupancy and appliance type is randomly sampled for each house in the Behavioural Water Use nodes.
- Average appliance demand – rather than sampling from the probability distribution of water consumption for a usage event for each appliance, the average water use is selected. This mode can be used in conjunction with Fixed or Sampled appliances and occupancy.
Further details on these configurations are given below in Behavioural Model Configuration.
The statistical distributions used by BESS to generate the sub-daily indoor water use are based on the end-use study of Roberts et al. (2005). Users are encouraged to check that the predicted water use statistics provided by BESS match their expectations.
BESS uses a diurnal pattern based on Roberts et al. (2005) to vary the probability of water use events occurring throughout the day. Future versions of Urban Developer will enable users to input their own diurnal pattern.
For outdoor water use, the behavioural model uses a time series or monthly varying pattern of average daily values, which can be input by the user - similar to the average daily model. For the sub-daily outdoor water use, the daily values are evenly distributed throughout the day. Future versions of the behavioural model may incorporate the behavioural impact daily weather has on outdoor water use variability (Micevski et al., 2011).