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BESS
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Introduction
The behavioural model provides simulation of water use using the Behavioural End-use Stochastic Simulator (BESS) of Thyer et al. (2011), described further in the Urban Developer Plugin SRG.
For indoor water uses, the water use simulations for each household are based on the type of water-using appliance (end-use) and the occupancy of that household. The difference from the average daily model applied in the Average Water Use node 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.
By default, BESS uses a sub-daily diurnal pattern based on Roberts et al. (2005) to vary the probability of water use events occurring throughout the day.
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 sub-daily outdoor water use, daily values are evenly distributed throughout the day.
The Behavioural Water Use node allows the user to specify a unique combination of end-uses which will be applied to one or more houses. In this way the node can become a template representing a specific urban demand configuration. For example, a single node can be configured to represent all Detached homes with a Pool.
Contents
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Node Dependencies
The Behavioural Water Use node requires that the following inputs are configured through the Urban Developer Options:
- Climate inputs
- Diurnal pattern
- Appliance types
- Sampled Appliances & Occupancy (optional, required for the behavioural model with sampled appliances and occupancy only)
The allocation and application of these parameters is further described in the Urban Settings section in the Urban Developer Plugin User Guide and the Behavioural Model Configuration section in the Urban Developer Plugin SRG.
Restrictions
There are restrictions on which node inputs and outputs you can connect together. See Urban Developer node connection rules.
The Behavioural Water Use node is available for Urban Scenarios only.
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| Node Property | Notes |
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| Number of houses | Specify the number of houses the node represents |
| Occupants per house | Specify the number of occupants per household (applies only when the behavioural model configuration is set to Appliances. When the behavioural model configuration is set to Sampled appliances and occupancy, these properties are grayed out in the user interface. Refer to section 2. Urban Settings for details.) |
| Average appliance demand | Switches between a Stochastic (BESS) and Average method of demand generation Stochastic demand generation will use random number generators to see if water use events occur throughout the day, based on the hourly likelihood for the particular end use. Some end use items also have a random generator for the volume of water used and / or the length of the event. Average demand generation will calculate the average event likelihood and demand volume for a timestep. This means each end use will generate the same demand rate for all timesteps until parameters change to affect end use item rating being used, number of people in the house, or number of houses being modelled. Outdoor use is the exception to this rule as it uses a specified data source, function, or monthly pattern for this demand generation. |
| End-use appliance type | Indoor end-use includes showers, taps and dishwashers, toilet and dishwashers as appliance types. Specifications for indoor water use appliance types are set under the Urban Developer Options described in section 2. Urban Settings. Pool is currently the only end-use available under Outdoor end-use |
| Outdoor average daily demand | The average daily outdoor demand can be specified using a single value, a time series, a function or a monthly pattern. By default a monthly pattern is applied. |
| Supply source priorities | For each indoor/outdoor end-use, specify which supply sources are available, in order of preference. |
| Discharge breakdown | For each indoor/outdoor end-use, specify the percentage of water discharged as blackwater, greywater, or Irrigation/other wastewater. |
User Interface
The Behavioural Water Use node is configured via the node Feature Editor, illustrated below in Figure 1. to Figure 4. The first window of the Behavioural Water Use node (Figure 1) allows the user to set the Number of houses which will use the end-use configuration specified on this node. This will be 1 if applying the node as a template for an Urban Combination Configuration run. Water end-use is categorised as Indoor and Outdoor use.
The average appliance demand is an option that can be used in conjunction with sampled or fixed appliances and occupancy.
Average values for usage frequency and water consumption are used, rather than simulating the water consumption for individual appliance usage events by sampling from the probability distributions set up under the Urban Developer Options described in section 2. Urban Settings. The average values are configured in the Appliances menu.
The average appliance demand model is enabled using the Use Average Demand check box in the Behavioural Water Use node Feature Editor.
Figure 1. Behavioural Water Use node editor
Indoor demand
Four end-use options are available for Indoor water demand allocation (Figure 2). Each end-use is defined by an end-use Rating (according to specification configured in the Urban Settings interface of the Urban Developer Options), a Supply type and a Discharge type.
Supply occurs according to the priority allocated to a particular Supply type. For example, for the end-use Toilet (illustrated in Figure 2) rainwater is the first preference for toilet flushing and, if no rainwater is available, then Mains water is used as the second preference for flushing. Un-checking Use for a supply source specifies that it will not supply that particular end-use. Two unspecified Alternate Supply options are available to represent supply from a source other that Mains or Rainwater, such as greywater.
Discharge can got to blackwater, greywater or an irrigation/other option. Discharge to each option is allocated as a part of the total discharge and the values will be re-scaled so that they sum to 100%.
Figure 2. Configuring Indoor end-use options in the Behavioural Water Use node editor
Outdoor demand
Outdoor demand typically replicates a seasonal variation in water use (e.g. domestic garden use which is higher during dryer months) and can therefore be modelled using a Time series, a Function or a Monthly pattern (Figure 3). Outdoor demand is also more likely to be impacted by long-term variations in climate.
As with the Indoor end-uses, a Supply type and a Discharge type are available for Outdoor demands. A Pool (Figure 4) can be added and can have different Supply and Discharge types to the general Outdoor demand.
Figure 3. Configuring Outdoor demand options in the Behavioural Water Use node editor
Figure 4. Configuring Outdoor demand options in the Behavioural Water Use node editor
References
Roberts, P. (2005) 2004 Residential End Use Measurement Study, Final Report: Yarra Valley Water, Victoria.
Thyer, M., Micevski, T., Kuczera, G., and Coombes, P. (2011) A Behavioural Approach to Stochastic End Use Modelling. Paper presented at Oz Water, 9-11 May 2011, Adelaide.
Acknowledgements
This material has been adapted from:
eWater Cooperative Research Centre (2011) Urban Developer User Guide: Urban Developer v1.0.0, eWater Cooperative Research Centre, Canberra, 29 June 2011. ISBN 978-1-921543-40-1