Hello Marco,

since you write about " Stock Type", I reckon you are actually specifying a material with a quantity in a place (circle element). This is not necessary. Specifying stocks is used in different modelling situations.

There are "only" two simple things you have to do to make a model calculate:

1) specify all processes (squares). Make sure that you enter the process description with flows and coefficients on the input and output side. To verify that a process is correctly specified, the red marker symbol must have disappeared.

2) specify **one manual flow** only. This is typically the product flow (one unit of product) or any other given flow. Only one flow in the life cycle model should purple.

Fulfilling these two requirements should lead to a calculable carbon footprnt model. After calculating the model all arrows where the calculation has yielded flows are shown in black. Branches that remain gray have not been calculated.

Stating to manual (purple) flows will in most cases lead to an over-specification. All flows should be calculated from the one given (manual) start flow.

I strongly recommend that yor have a look at the tutorial, where there is a step-by-step description of an example carbon footprint calculation.

Should you need help in getting your first carbon footprint model to work, please contact support@umberto.de (you can attach the .umberto file to your e-mail inquiry so that our help desk can have a look).

Enjoy your work with Umberto NXT!

Peter