Monte Carlo Simulation option unavailable in product system calculation properties window

Question

I'm trying to perform a Monte Carlo Simulation with a process built in the USLCI database, but the calculation window won't allow it as an option.
I added uncertainty to flows in the process by importing the Ciroth et al data quality system for flows. Then I use the pedigree matrix to create an uncertainty distribution.
When I create a product system and click on "Calculate," the option to perform a Monte Carlo is unavailable (grey text).
How do I get the calculation setup to allow MC simulations? Am I missing a step somewhere? I'm more familiar with ecoinvent where the functionality is built in, so maybe there's some edit I need to make to the USLCI database.
For reference on versions: openLCA 2.3.0, USLCI 1.2024-10.0

Comments

I'm also running into an issue with this and troubleshooting. At this moment, I suspect that there's a problem somewhere in the model graph (like an output flow connected to the input of the same process). As a starting point you might try building out the product system using only default providers.

I'm guessing openLCA is finding the issue with the product system though and disabling Monte Carlo. Any way for us to see what flows/processes might be causing the issue?

Answer 1

Hello mrmlca,

Unfortunately, the Monte Carlo simulation is not available when using libraries at the moment. We are currently working on it and hope to include it in upcoming releases.

Regards,

François

Comments

Thanks Francois! For anyone who runs into this issue and comes to this thread, you can consider using an older version of USLCI (2024 Q1 and earlier) since libraries were implemented in 2024 Q2.

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Hi Francois!

Wondering if there has been any update on this? Would love to be able to run Monte Carlo Simulation on USLCI databases with libraries. Thanks!

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Hi François,
What is the statut on this issue please ?
Performing Monte Carlo Simulations with librairies would be very usefull

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Hi Franck, indeed we are aware but it is quite some effort (and flexible libraries contradict somewhat the initial library idea) - we could discuss a small implementation project if you find this interesting and worthwhile, let us know please.

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Thank you, Andreas.
Actually, I should clarify. I do not want to run a Monte Carlo analysis on the library datasets themselves (e.g., to calculate the uncertainty inherent in the ecoinvent datasets).
What I would like to do is run a Monte Carlo analysis based on my own parameters, which I use in the LCA model. For example, the quantities of a product flow, whose provider is an ecoinvent dataset from the library.

Answer 2

Hi, can you post a screenshot? The MC simulation is agnostic to the database, in case there is no uncertainty there are no results, but the option is still offered. See here for our version of the LCA Commons database.

Thank you!

Comments

I'm seeing that in my own test. The second I add a process from a library, the option gets greyed out.