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2/6/2012 : 1:01 am : +0100

Documentation

Flows

Flows are streams of substances. In openLCA they are in classified order after certain themes as you can see below.

Every flow has a flow type. There are three flow types in openLCA:

  • Elementary flows: Material or energy entering the system that has been drawn from the environment without prior treatment, or material or energy leaving the system that is released into the environment without subsequent treatment
  • Product flows: Products entering or leaving to another process
  • Waste flows: Products leaving the product system

Note that you cannot change the flow type later on, as this could create several problems (as: product systems without product if you change a product flow type to an elementary flow type; products in LCIA methods if you change a flow type form elementary flow to product flow). Therefore, if you really need to change the type of a flow, it is required to create a new flow but with the different type then.

Moreover every flow has flow properties as e.g. mass, volume or amount. Flows can have several flow properties, the reference flow property is highlighted in bold.
You can see the specifications of a flow when double-clicking on it.

Creating a new flow

If you want to create a new flow, open the wizard and assign a reference flow property and a flow type. These assignments can also be changed later on. If there is no appropriate flow property, you have to create one first.
The reference flow property is used in the calculation: All flow properties are expressed in relation to the reference flow property.

At the bottom of the Flow editor, you find two tabs. On the flow properties tab, you see (evidently) the flow properties of the flow. You can add new properties by dragging flow properties from the left category tree into the flow property table (see screenshot).

The reference flow property is printed in bold.

By default, the conversion factor is 1.0; it expresses the conversion between the reference unit of the reference flow property and the reference unit of the other flow property.