myUmberto - Forum

Umberto NXT LCA => General => Topic started by: Chris P. on May 08, 2015, 13:19

Title: Merging impact of different processes
Post by: Chris P. on May 08, 2015, 13:19
Hello there,

I am a new user of Umberto NXT LCAand I have reached the point in my model, where I need to analyze my impact results.

I have several individual subnets in my main plan, and since all these subnets utilise electricity and compressed air I have used two main processes (electricity and air) to supply them.

The main purpose of the above approach was to have a better overview of the consumption of the above with Sankey diagrams (please see attached screenshot).

The problem I am facing with the analysis is that he flows of electricity and compr. air are not directly associated with the impact of the subnets. More important is the fact that some processes (subnets) exhibit no impact at all, since their only inputs are electricity and air.

Is there a way to merge the corresponding impact of electricity and air to the subnets without losing in visualisation?

Kind regards,
Chris
Title: Re: Merging impact of different processes
Post by: uniquename on May 12, 2015, 07:36
Hi Chris,

the reason why several of your subnets seamingly show no impact at all is, that only emissions emitted to the environment or ressources taken from the environment are causing impact. These are depicted by so-called elementary flows.
You have switched on the sankey mode, vizualising material flows (in different units).
If you switch the sankey mode to show an impact sankey, the sankey diagram will show you "where the impact comes from". This means that even intermediate flows (like electricity) will show you the impact that is allocated to them.
To change to this sankey mode, use the dropdown-menu next to the "show sankey diagram" button and choose an impact category that suits your analysis.

This is also shown in the second tutorial (Beginner), have a look at the figure that is taken from that document.

Does this help for the visual analysis of the net?

Have a nice day!
uniquename
Title: Re: Merging impact of different processes
Post by: Chris P. on May 18, 2015, 11:24
Hello uniquename,

Firstly of all thank you for your reply and secondly I would like to apologize for the late reply.

I am afraid I did not make myself clear in my first post, so I will try to illustrate the problem I am facing with another example.

I want to model a linear production chain which comprises many independent processes/steps.
These processes however, utilize many common materials and resources. In my first post I used the example of electricity and compressed air.

What troubles me is the modelling approach of such processes (be it materials or energy). For better visualization purposes, I would prefer to have a main plan, where I could put all the necessary flows for my production chain and associate them with the individual production steps.

This approach is working fine with the Sankey diagrams by switching between the various impact categories and having the visualization of the flows. The "problem" occurs in the raw data analysis and the contribution analysis of each process, since the impact of each process appears seperately without being allocated to the production steps.

The only way I have found so far to cluster the production steps/processes and their comprising sub-processes and flows is to create subnets. However, with this approach I have to put all the necessary processes in the subnet, thus losing in visualization from the main plan. Another drawback of this approach is that, whereas in the first modelling approach I could simply use one process (e.g. electricity) and connect it with all the required production steps, with the subnet modelling approach  I have to separately create them.

This is quite cumbersome, especially for example if I want to use a different dataset for electricity and run sensitivity scenarios. Instead of replacing a "main" electricity process, I have to edit each production step and replace the electricity datasets separately.

The previous LCA software I had been using allowed  the user to manually assign a group name to all the processes and sub-processes (either custom made or proprietary) used in the model. In this way, in the impact assessment phase, the results could be clustered and sorted accordingly, providing this way a great flexibility for contribution analysis in form of charts and tables.

To conclude, my question would be whether there is a similar function in Umberto or if somebody could suggest a workaround for my problem.

Kind regards,
Chris