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What is difference between Unit demand control center and demand control center?
Unit demands and demands are different in a model so they are entered separately in unit demand control center and demand control center respectively.
Demand control center -
In the Demand control center, we specify the demands for the junctions which are pattern based as shown below. Also, zones to which elements are assigned are also visible here. For V8i versions it can be accessed through Tools>Demand control center and for connect edition versions, it can be accessed through Components>Demand center>Demand control center.
In this hydraulic pattern can be assigned to the junctions which can be defined under Components>Patterns>Hydraulic Pattern as shown below. To assign the patterns to all the junctions globally, right click on the Pattern (Demand) column>Global Edit>select the pattern to be assigned.
In the demand control, we apply the total demand that will be supplied by that particular junction, irrespective of based on land unit, population unit or count. Here the demand to be supplied by that junction is calculated externally and the final demand value is entered in the demand control center.
So when you know the total demand load to be supplied any particular junction, you should use demand control center, otherwise unit demand control center should be used along with unit demands, which will calculate the demands for you based on your input data like population units, area, count based etc.
Unit Demands and Unit demand control center –
A unit demand consists of a unit (person, area) multiplied by a unit demand (gal/capita/day, liters/sq m/day, cfs/acre). The units are assigned to node elements (like junctions) while the unit demands are created using the Unit Demands dialog box.
Unit demands are the demands where you can specify per capita requirement of say a house, hospital, office, airport, hotel etc. It can be based on area, population, count etc. Once you have specified the unit demand then in the unit demand control center, you need to specify number of those unit demands. E.g for hospital, per bed demand i.e. unit demand is mentioned then number of units here would be number of beds.
Also, you can specify the pattern here, which will be applied to these unit demands just like demand control center.
While preparing the GIS data for importing demands into model, it is best to assign the unit demands to the polygons in GIS than to nodes, to use Loadbuilder.
The three types of unit demands are explained below.
Population Unit Demand
Unit Demand —Lets you specify the amount of demand required per population unit.
Population Unit —Lets you specify the base unit used to define the population-based demand.
Count Unit Demand
Unit Demand —Lets you specify the amount of demand required per count unit.
Count Unit —Lets you specify the base unit used to define the unit-based demand.
Report Population Equivalent —Checking this box enables the Population Equivalent field, letting you specify the equivalent population count per demand unit.
Population Equivalent —When the Report Population Equivalent box is checked, this field lets you specify the equivalent population count per demand unit. For area based demands, this is essentially a population density, or population per unit area.
Area Unit Demand
Unit Demand —Lets you specify the amount of demand required per area unit.
Area Unit —Lets you specify the base unit used to define the area-based demand.
E.g. If you have applied unit demand of 220 L/day, based on population data for an apartment as shown below. The population unit here is guest, so we are considering that each guest in that apartment requires 220 L/day of water.
Now we need to apply the number of unit demands in the unit demand control center, let’s consider 10 number of unit demands are assigned to a junction J-2 here, meaning the demand of 10 guests from that apartment will be supplied by junction J-2. So, the total demand at that junction is 2200 L/day, to which defined residential pattern will be applied in the EPS run.
You can apply the demands or unit demands to a selection set only. For that create a selection set, (How to create selection set ) and then go to demand control center or unit demand control center and go to query>and select the particular selection set. This will filter only the selection set to which you want to apply the demand.
You can also import the demands using tools called Loadbuilder and Modelbuilder. More information about it can be found in the "See Also" section below.
More information about demand control center and unit demand control center can be found in the help documentation, to be searched by phrases "Unit demand control center" and Demand control center".
How do each of the Loadbuilder methods work?
Troubleshooting and Understanding LoadBuilder
Importing Demand and Loading Patterns using ModelBuilder
Importing Demands From A Spreadsheet