Modeling consumable resources such as money, energy, water, etc. Useful for modeling the consumption and replenishment of a resource.
1. Create a variable to represent the consumable resource (see Variables).
2. When an activity, storage, or routing uses a consumable resource, decrement the variable’s value using the DEC statement in the Action logic.
3. When the resource is replenished in the model, increment the variable’s value using the INC statement in the appropriate Action logic.
Example: A hydro-electric power plant wants to track its usage of water, a consumable resource. Power Request (the entity flowing through the model) has an attribute called BTU indicating the energy level required to produce the needed power. The Steam activity uses 1,000 gallons of water for every BTU, and the Recycle activity restores about 70% of the water back into the system. The question is, how many gallons are not recovered.
TO DO: Create a variable called v_Water. Enter the Action logic as shown above for the appropriate activity.