The Urban Settings menu is used to configure options that will be applied to multiple elements in an Urban Scenario.For For example, it is used to specify the climate data that will be applied to all climate-dependent nodes, such as the Roof and Behavioural Water Use nodes.
Setting up the Urban Settings is specified here as the second step in a three-step process of configuring and running an Urban Demand Scenario (Figure 1), since common default Urban Settings are available to be used when building the nodes. However, if e.g. new end-use patterns are being specified then these should be allocated prior to the node configuration so that they are available for node configuration.
Figure 1 Urban Settings overview
The Urban Settings menu options are further described in the following sections:
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The Urban Settings menu is accessed via the Source Toolbar menu item Edit » Urban Developer Options.
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The appliances and occupancy for each household can be specified in several different ways, configured under Edit>>Urban Developer Options.
Sampled appliances and occupancy
The behavioural water use model with sampled appliances and occupancy allows you to specify random sampling of occupancy and appliance types, for each household, from statistical distributions.
Using the behavioural model with sampled appliances and occupancy is only recommended when you are simulating a larger number of households (> 400) and you do not want to set the appliance types /occupancy for each house.
When using the sampled appliances and occupancy model, the occupancy and appliance type node properties do not need to be configured. Other properties, such as the number of households, supply and discharge preferences do need to be configured. Refer to the Node Properties for details.
The sampled appliances and occupancy model is enabled and disabled using the Sampled Appliances & Occupancy Menu.
Details of the sampled appliances and occupancy algorithm are provided in Thyer et al. (2009) and references cited therein, a summary is provided below.
Capturing Spatial Variability in Occupancy and Appliances
The household size and the type of water using appliances varies from household to household. To capture this spatial variability the household size and appliance type for each type of water use event is randomly sampled for each household from a probability distribution based on the proportion of household sizes/appliance types. The probability distributions are specified in the Sampled Appliances & Occupancy Menu.
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Individual end-use events are generated in a two-stage process. The first stage determines whether a given water use starts in a particular time step, and is based on the probability of occurrence, for a particular end-use. The second stage tracks the subsequent behaviour of that water use over the following time steps, and is dependent on the end-use event volume and water usage pattern.
In general, the probability of occurrence for each event is a function of the frequency of events per person per day, the household size and a diurnal factor. The diurnal factor converts the frequency of events per day into the probability of an event occurrence in a given minute. The water use event volume and the water usage pattern is dependent on the type of water use event and the appliance type. In general, the end-use event volume is sampled from a probability distribution, and the water usage pattern is applied to this volume to produce a water use time series.
For each appliance, the frequency of events per person per day, and the probability distributions of water consumption for an event, are defined in the Appliances menu.
Sample size requirements
If you specify sampled appliances and occupancy, you must specify a minimum number of houses in order to provide a statistically-reliable sample of the household occupancy and appliance type.
Due to random sampling in any particular Urban Developer run, the percentage of houses actually sampled for each household occupancy and appliance type (the sampled percentage) will not be exactly the same as what you specify (the true percentage).
For example - if you specify only 10 houses, with a true probability of 0.2 for 3-Star showers and 0.8 for 1-Star showers, the chance of the sampled percentage being very different (eg: 0.5 3-Star and 0.5 2-Star) is much greater than with a large sample size.
The recommended minimum number of 400 houses ensures that for true percentages greater than 10%, the sampled percentage of houses is within 30% of the true percentage for 90% of the time.
You can specify a number of houses smaller than 400, but should be aware that the sampled percentage of household occupancy and appliances types may be different than the percentage you originally specified.
Random Seed
Random seeding provides a way to control randomisation of simulation outcomes. Random seeding applies to both sampled, and fixed, appliances configurations. The seed applies to both allocation of appliance types (eg Shower 0-Star or Shower 3-Star) to a house, and the actual water use, given the specified appliances. You can obtain repeatable results, or varied results, or repeatably-varied results with the random seed settings.
When using probabilistic simulations in models such as BESS, it can be difficult to reproduce results due to the random generation of water use.
The random seed is currently not editable in the Urban Developer Plugin, but this feature is planned for future versions to allow repeatable results with sampled appliances and occupancy.
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. The water consumption for individual water use events is still sampled from probability distributions, as described in Capturing Temporal Variability in Indoor Water Use Events.
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.
For this behavioural model configuration, you set the indoor end-use appliance types and occupancy for each water use node. Refer to the Node Properties for details.
The fixed appliances and occupancy model is enabled by disabling the Sampled Appliances & Occupancy Menu.Options (Figure 2).
Figure 2. Urban Settings breakdown