Behavioural End-use Stochastic simulator (BESS) – fixed and sampled
The behavioural model provides simulation of water use using the Behavioural End-use Stochastic simulator (BESS) of Thyer et al. (2011). BESS stochastically simulating individual end-uses (outdoor, shower, washing machine, toilet, tap etc) at the household scale at sub-daily time steps using algorithms which probabilistically simulate an individual household’s use of common household water-using appliances. The conceptual framework for BESS is provided as follows:
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 currently supported are listed in options for indoor water use 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 two different ways:
- Fixed occupancy and appliances – where the type of appliances and occupancy for each house are fixed by the user and
- 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 water use nodes that are set to Behavioural. Further details on these two different configurations are given in Behavioural model configuration.
- Average occupancy and appliances – calculates the mean for the end use instead of calculating the demand per minute (based on events) for each end use, as in the fixed and sampled occupancy methods. These values can simply multiplied for each house (as they will all have the same average).
For outdoor water, the behavioural model uses monthly varying, 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).
Diurnal Pattern
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 variation to vary the probability of water use events occurring throughout the day. It disaggregates the daily demand data to a sub-daily time-step using a non-dimensionalised diurnal pattern.
Fixed Behavioural
Sampled Behavioural -
Average Behavioural
For Water Use nodes set to behavioural mode, there are two options for specifying their configuration.
From the Urban Developer main menu, select Configure > Water Use. The following table explains the menu options.
These water use configuration options act only on Water Use nodes within the scenario that are set to the behavioural model. These options have no effect on any Water Use nodes in the same scenario that use an Average Daily model.
You can have water use nodes with both Average Daily and Behavioural models active in the same scenario, but the settings specified on the Configure menu only affect those water use nodes in the scenario which use the Behavioural model.
Behavioural model with fixed appliances and occupancy
The behavioural water use model configuration with fixed appliances and occupancy allows you to set appliance types for each end use (showers, washing machines, and toilets), household occupancy and outdoor use for each water use node.
Using the behavioural model with fixed appliances and occupancy is the recommended approach when you are simulating a smaller number of houses (< 400), and you want to specify exactly the type of appliances and occupancy for each house.
Similarly to the average daily model, you select the supply source preference for each individual end use.
For this behavioural model configuration (fixed appliances and occupancy) you set the indoor end-use appliance types and occupancy for each water
Menu item Notes Fixed appliances and occupancy This option produces a repeatable, probabilistic simulation of water use, using fixed (ie user-specified) appliances and occupancy rates for each water use node. Sampled appliances and occupancy This option produces a repeatable (if configured in Random Seed Settings, see below), probabilistic simulation of water use, using sampled appliances and occupancy from user-defined probability distributions. Random Seed Settings This option allows you to set the random seed used by the BESS model for water use simulation - this enables production of repeatable random series. See Water Use node (page 143) for more information. Table
These water use configuration options act only on Water Use nodes within the scenario that are set to the behavioural model. These options have no effect on any Water Use nodes in the same scenario that use an Average Daily model.
You can have water use nodes with both Average Daily and Behavioural models active in the same scenario, but the settings specified on the Configure menu only affect those water use nodes in the scenario which use the Behavioural model.
Thyer, M.A., Duncan, H., Coombes, P., Kuczera, G. and Micevski, T. (2009). A Probabilistic Behavioural Approach for the Dynamic Modelling of Indoor Household Water Use. 32nd Hydrology and Water Resources Symposium, 30 November – 3 December 2009, Newcastle, Australia.
Roberts, P. (2005). 2004 Residential End Use Measurement Study, Final Report: Yarra Valley Water, Victoria.
Micevski, T., Thyer, M., Kuczera, G. (2011). A Behavioural Approach for Household Outdoor Water Use Modelling. Paper submitted to Water Resources Research (April 2011).