ask.openLCA - Question and Answer (Q&A) on Life Cycle Assessment (LCA) - A Life Cycle Assessment (LCA) Community - Recent questions and answers

Answered: exchange with invaild process owner @0

Fri, 07 Aug 2026 10:05:37 +0000

I edited your title (I CAN'T FIND THE PROBLEM will not be useful for anyone to respond), you have an exchange that does not have a valid process (which can happen when you work with scripts) -> validate the database then you should be guided to where the issue is.Good luck!

Process for recycled materials

Thu, 06 Aug 2026 08:09:27 +0000

Hi . I am quite new to OpenLCA. Keen to understand if one needs to model a product system that use recycled material such as plastics, glass and metal as their input where can i find such a database ? is a free version available ?

Format ILCD+EPD

Tue, 04 Aug 2026 11:24:41 +0000

Is it possible to create an EPD in format ILCD+EPD using OpenLCA?

Best regards,

Vinh

Answered: EF 3.1: missing CFs for “Arsenic, ion” emissions to water and soil?

Fri, 31 Jul 2026 13:09:55 +0000

The compatibility of the openLCA LCIA Methods to the ecoinvent version is written in the methods description inside openLCA. The methods package version 2.8.2 is compatible to ecoinvent 3.12. You have not written which method version you are using, but I assume that you used an older method version, where the description only states the compatibility to version 3.11 or earlier.

EF 3.1 characterizes the arsenic ion emission to air, soil and water for non-carcinogenic human toxicity in the original implementation by JRC, in the ecoinvent LCIA method implementation (inside the ecoinvent databases by default), as well as in the openLCA LCIA method implementation.

I assume that you used an older methods package version that is not compatible to ecoinvent 3.12. We use now in ecoinvent 3.12 all original UUIDs for elementary flows that come from ecoinvent, because it has certain advantages of compatibility to other tools/sources/mappings. For this reason, some elementary flows that had a new UUID in the ecoinvent Nexus version 3.12 needed to be added to the characterization factor tables of a new openLCA methods package version.

You can try to fully delete the openLCA methods and openLCA impact categories in your database that have the older methods version (to have a clean new import), then you import the newest methods version 2.8.2 and you will see that the arsenic ion is characterized.

There is no need to change the ecoinvent LCIA methods that are inside the database by default, since these ones characterize only the ecoinvent elementary flows and always stay as they are originally delivered by ecoinvent. So these ones are always compatible to the ecoinvent version where they are included, but only to this database and no other databases usually.

Have no regionalized calculation window when calculate a product's impact

Thu, 30 Jul 2026 02:19:32 +0000

Hi there,

I was trying to run a result using AWARE LCIA method using the geographical CFs, and have built a product for the corresponding process. However, when I clicked on the "calculation" button, the "calculation properties" window showed up, and if I press "Finish", the running getting started, the result showed the regional CFs is not used. But I remembered that there supposed to have a window after this one and can choose the calculation mode "lazy on", "regionalized" and something else, I tried restart OpenLCA but it still not appeared. How can I deal with this problem?

Regards,

Dongyan

Answered: Question About LCA Commons Database Options

Wed, 29 Jul 2026 12:58:27 +0000

Sure - LCACommons alone has some incomplete supply chains since quite models were initially modelled with ecoinvent and the ecoinvent processes cannot be included in the publicly distributed LCACommons DB. In the LCA Commons 2025 (ecoinvent 3.11 Cutoff) these supply chains have been completed with ecoinvent datasets. As this creation was some effort, we charge a fee for this combined database (and you need a Nexus ecoinvent license). As the name says, the database is linked to 3.11 but we are currently working on the link to 3.12.

All the best,

Andreas

Answered: TRACI Federal Commons JSON Import failed

Wed, 29 Jul 2026 09:29:24 +0000

They write:

"Usage Notes for zip file: This file was tested to correctly import into an openLCA v2.1 database already containing flows from the FEDEFL v1.2. It will provide matching characterization factors for any FEDEFL elementary flow already present in the database. This file itself does not contain the elementary flows. Use of this "No Flows" method is described on https://www.lcacommons.gov/lcia-methods-without-flows."

Better use the latest TRACI 2.2 and the Federal LCA Commons source with the Federal elementary flow list: https://www.lcacommons.gov/lca-collaboration/Federal_LCA_Commons/TRACI_2_2/datasets

Difference between entering uncertainties for parameters vs for inputs/outputs in a process, for Monte Carlo sim

Mon, 27 Jul 2026 12:44:11 +0000

Hello,

I'm looking to do a monte carlo sim of my model, and intended to add uncertainties for my global parameters when possible, and only in the input/outputs of my flows when they aren't dependent on any parameters. However, after some testing, it seems like only the uncertainties entered on the input/outputs are recognized when running a monte carlo simulation. One reason I want to use the parameters is to maintain mass balance (link the uncertainty of inputs and outputs by using the same parameter).

Does anyone have experience with this and know if there's a workaround of some sort?

Thanks in advance,

Ben

Answered: Anomalies in some datasets in the Ecoinvent 3.12 library.

Mon, 27 Jul 2026 08:50:21 +0000

Thank you for finding this. We discussed before your observations and now we have a good example from you to look into it. It seems that it affects unit processes where the quantitative reference is not the reference unit. In your example, the unit process uses m*a and the reference unit is km*a. This should not make any difference. The library is scaling everything correctly (as you can see by the factor of 1000 in the inventories and by changing the units from m*a to km*a), but there seems to be a bug that the input products are subtracted and not added. In other, similar processes everything works well and no inputs are subtracted. Also when testing many processes, there was no difference, so my first guess is that it has to do with the different reference unit in a few processes. But our developers will look into this.

Answered: Running a headless openlca and pulling from collab server

Fri, 24 Jul 2026 10:33:35 +0000

Aha.... standard git commands!

https://greendelta.github.io/lca-collaboration-server-manual/chapter_3_10.html

I'll leave my question up in case anyone else googles it

.

Answered: After registering for the ecoinvent license as low income country, from where can we download it?

Fri, 24 Jul 2026 09:14:23 +0000

From Nexus, downloads - but you need to send in forms to prove your status, and ecoinvent needs to approve these forms. To share it, the professor can e.g. share it within the university department making sure it is only used by university students.

Answered: Can an intire Unit Database be exported as a System Database?

Fri, 24 Jul 2026 09:11:29 +0000

Quite timely question, the new openLCA version allows to calculate an entire unit process database as system process database. It is available on the openLCA download page, since yesterday (on the downloads page, openLCA, other).

Feedback is welcome..

Change unit in unit group

Fri, 24 Jul 2026 05:32:15 +0000

I can not change unit in unit group.

In amount * lenght there are p*km and pkm and I do not want them there because there is a specific person * length. I can not delete it in amount * length

It's a problem because even if I set as reference v*km for a transport service defined as vehicle km in the result appears p*km.
This unit group is used in a lot of flows. How can I do?

Answered: How do I model scenarios in OpenLCA?

Wed, 22 Jul 2026 09:12:13 +0000

You could go to projects, and then have the same product system multiple times as "variants", and specify the parameter values for each of the variants as you want. You can then calculate all in one go. Also, probably, parameter sets could be useful to you as they help to group parameters.

Good luck!

Andreas

Answered: Difference in results

Wed, 22 Jul 2026 08:45:06 +0000

Do you have no validation errors (right-click database "validate")? Are all your imported foreground processes correctly linked to the same provider from ecoinvent (please click "Check linking properties" and make sure that there is no processes without default provider set)? Is the required amount and the calculated inventory (the total elementary flow results) the same?

Which free database and compatible LCIA method should I use in openLCA 2.6.2 for a UK wheat-straw CHP LCA?

Sun, 19 Jul 2026 18:02:54 +0000

I am using open LCA 2.6.2 for a UK university dissertation on a cradle-to-grave wheat-straw gasification CHP system producing electricity, heat, char, tar and ash. I need multi-impact results and a fossil-energy baseline to calculate lifecycle carbon reduction for carbon-finance analysis.

Ecoinvent is unaffordable, while ELCD 3.2 with IMPACT World+ left important flows uncharacterised, and the JRC ILCD 2011 method package produced missing-flow errors.

Which free inventory database and compatible LCIA method would be most suitable, and how should I address UK geographical representativeness where only European datasets are available?

Answered: No puedo hacer el registro en OpenLCA nuxus

Sun, 19 Jul 2026 11:50:31 +0000

I think I understand your text, probably you meant "nexus" not nuxus. You do not need to try from different computers but just verify the email.

Answered: System Dynamics Models

Sun, 19 Jul 2026 11:48:34 +0000

Hi, thank you, this is coming; we had a really nice session in the last openLCA conference, and some presentations are available on the greendelta resources page https://www.greendelta.com/resources/, e.g. https://www.greendelta.com/wp-content/uploads/2026/04/SDolcaconf26_ac_final_commentsTS_compressed-1.pdf, https://www.greendelta.com/wp-content/uploads/2026/04/133-T7-Alex-Koch.pdf.

SHDB Worker Hours Model: does the $ value for an input mean producer price, or something else?

Fri, 17 Jul 2026 14:44:18 +0000

In the SHDB (Social Hotspots Database) Worker Hours Model, what exactly does the monetary value (e.g. $1) entered for a Country-Specific-Sector input represent? Is it the producer/basic price (the price at the producer, before transport, trade margins, and import duties are added), or is it something else and if so, what?

Answered: Will ecoinvent v4 be available for perpetual licenses?

Fri, 17 Jul 2026 10:35:18 +0000

Hi, good question, in the end this depends on ecoinvent I would say, and is maybe even not fully decided yet.

Answered: Library creation

Fri, 17 Jul 2026 09:43:48 +0000

A library is an immutable database tha can be even pre-calculated (but don't has to) to speed up calculation. For example, input-output databases like PSILCA or exiobase get massive reductions in the calculation durations, whereas for ecoinvent, the non-library database or the non-precalculated libraries in openLCA are already so fast in calculation speed that the speed advantage from pre-calculated libraries is not needed here.

But even if not pre-calculated, a library is an immutable database, meaning that it cannot be changed anymore. Because of this immutable nature, there is no possibility that modifiable parameters exist inside the library itself. Of course, parameters can still be used in the foreground processes that do not belong to the library, parameters can also be used in the foreground to vary inputs from the "background" library, but inside the library itself everything is fixed.

So when the library is created with openLCA, the set values of the parameters are "frozen" in and the parameter results are written into the exchange amount values. So the parameters do not exist anymore, but they are applied as set in the moment when the library is created. You will also see that, for example, different cost values inside a process are calculated for that process and put into the quantitative reference, or that units are changed to the reference unit of the specific unit group (and adapting the exchange amounts accordingly). So the library is kind of writing everything "in stone", but keeping the calculation results unchanged to the non-library database.

Do you have a use case when to use a library together with parameters inside that library? Why not using the non-library database for such cases?

Why is the water use impact category in EN 15804+A2 not regionalised?

Fri, 10 Jul 2026 09:09:11 +0000

I wanted to use the EN 15804+A2 add-on for ecoinvent with the corresponding EN 15804+A2 LCIA methods for an EPD.
However, I noticed that the water use impact category (WDP) is not regionalised and only considers emissions (the global characterisation factor of −42.95 is applied to unregionalised air emissions).

Could you explain why this choice was made, given that, on the other hand, in the openLCA LCIA methods, EF 3.1 uses regionalised characterisation factors?

I have seen several other questions regarding the water use LCIA, and I understand that it may create mass-balance issues considering the allocation applied in ecoinvent. Is this related?

Even taking this into account, I still consider it preferable to use regionalised characterisation factors. Would you recommend replacing this impact category with the EF 3.1 water use category from the openLCA LCIA methods instead? What would be the main drawbacks or limitations of making such a change?

Thank you in advance for any help

Answered: If I merge two databases, how can I understand which process belongs to which database? Thank you

Tue, 07 Jul 2026 08:54:48 +0000

Good question, sometimes the process dataset contains this in the description, but if you do this on the database / process level, it is typically somewhat messy. If you use libraries, this is very easy (as the library name is the database). If you want to stick to the "classic" process / database import, you could modify the first database (where you import into) e.g. by modifiying the description:

sql: update tbl_processes set description = description || ', from first_database.'

And then import the next database into this.

The download link for the example file provided in the tutorial is broken (404 error); how can I obtain the file?

Wed, 01 Jul 2026 11:46:17 +0000

I am studying a case study titled "Modelling PC and PET Bottles". The download link (https://www.openlca.org/wp-content/uploads/2020/06/chapter9_1.zip) mentioned in Chapter 9 is broken; where can I find it?

Answered: Methane GWP 100

Tue, 30 Jun 2026 11:53:11 +0000

https://www.linkedin.com/posts/conrad-spindler_i-have-a-question-to-the-pcf-iso-14067-activity-7361739572969431040-M5Ju?utm_source=share&utm_medium=member_desktop&rcm=ACoAACfod8sBoAfMBAmhAN0NsiM2HjQSlLgciqQ

The difference between fossil methane and biogenic methane is referenced in the IPCC 2021 report (https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter07.pdf) and is due to the ratio of the molar masses for CO2 (ca. 44 g/mol) and CH4 (ca. 16 g/mol), which is 2.75. So the difference is ca. 2.8 for complete oxidation. Or it is, as written in the IPCC 2021 report, a partial oxidation of 75% (0.75 * 2.75) plus an equivalent sink of CO2 from biogenic methane soil uptake and removal (0.7 kg CO2 eq.), which is again 2.8. Long story short, the difference between fossil methane and biogenic methane is 2.8. On top of this, also biogenic methane itself can be either 27 or 29.8, depending if biogenic carbon is accounted for in the greenhouse gas emissions or not.

The IPCC 2021 report mentions that "Methane from fossil fuel sources has therefore slightly higher emissions metric values than those from biogenic sources (high confidence). The CO2 can already be included in carbon emissions totals (Muñoz and Schmidt, 2016) so care needs to be taken when applying the fossil correction to avoid double counting.".

To avoid double counting, the biogenic methane factor is 27 in the 0/0 approach, where no biogenic carbon is explicitly tracked and accounted for, and the biogenic methane factor is 29.8 in the -1/+1 approach, where biogenic carbon is explicitly tracked and accounted. This is also the only difference between the "EF 3.1" LCIA method for PEF studies and the "EN15804 (based on EF 3.1)" LCIA method for EPDs. The -1/+1 approach to explicitly track biogenic carbon is also used in ISO 14067, therefore the characterization factor for biogenic methane has to be equal to the one for fossil methane which is 29.8.

Answered: What does the colour coding in the impact assessment results mean in openLCA?

Tue, 30 Jun 2026 10:56:14 +0000

ok - green is good, blue is small, red is negative.

Answered: Combining parts of EXIOBASE into ecoinvent

Mon, 29 Jun 2026 08:36:16 +0000

It has been a while since my initial question of how to combine ecoinvent with parts of EXIOBASE. Here is what I learned so far.

When you export all processes in one country's folder as JSON-LD and tick "Export default providers," you will only get the foreground system. If you want all the processes and flows that are needed in the background, you need to create a product system that includes all processes of that country as inputs, then calculate the system, and then export this product system with "Export default providers" ticked. LCIA results are the same now for the original and the one-country database.

You can import this one-country database into the ecoinvent database. If you calculate a product system using datasets from both databases, you will by default get results for ecoinvent and EXIOBASE separately. This is because the different impact methods have different elementary flows associated. But you can fix this quite easily if you create your own impact category and insert the flows from EXIOBASE and ecoinvent. For example, you create a new impact method called "GWP100" and copy the flows from CML 2001 baseline global warming from EXIOBASE and ecoinvent into this new impact category. You can find the flows under impact categories and then the tab "Characterization factors."

Be aware that all of this takes a lot of RAM and calculation time. The PC I am using has 32 GB of RAM and I allocated openLCA 30 GB. Still, all these calculations and exports took about 12 hours.

Although there are some minor issues, especially regarding performance, I did check all the other major competitors on the market like Brightway, GaBi, Umberto, and SimaPro, and I will stick with openLCA because of cost/benefit.

Now to my question: As I said, I calculated a product system containing all processes of EXIOBASE from one country as an input. When I now analyze the metadata of my database by clicking on Database → Content → Processes / Flows, I get the following picture: Processes are about 15% less in the one-country database (8,100) compared to the original EXIOBASE (9,800). But the number of flows (77,000) is more than 7× higher than the original EXIOBASE (11,000) after the export. In the original database, none of the flows are duplicated, while in the one-country database I see a lot of duplicate elementary flows. Addtionally, there a lots of new flows that are not part of the original EXIOBASE. For example Chromium III is 57 times listed in the one-country-database but does not appear once in the original EXIOBASE. In the original database, when I click in the navigation menu on Flows → Elementary Flows, in all the subcategories like "Emissions to air," there are only flows categorized as "unspecified." After the export, there are flows in all the other folders, e.g., "Emissions to air → High population density."

Why are these new flows like e.g., Chromium III added in the export DB and where do they come from? Is it necessary to have all these duplicate elementary flows? Is there a way to easily clean a database and delete unnecessary and duplicate flows?

Answered: Physical Allocation Question

Fri, 26 Jun 2026 09:53:27 +0000

Hi, thank you for the clear question; the contribution tree shows a tree / non-looped view of the calculated impacts for the connected life cycle you modeled. If you apply allocation for a process with two products / intermediate flows, you get "rid of" one of the products, thus this will indeed disappear in the view as it does not have impacts. If you do not apply allocation (it does not matter whether physical or economic), you have both products with impacts and thus two supply chains that are duplicates indeed. An intermediate flow is also a product, maybe not for the end consumer but for the process producing it, thus for the modeling and for whether to apply allocation or not, there is no difference.
What you should do? Apply allocation whenever you have more than one function (product produced, waste treated) in a process, and use the allocation type foreseen in goal and scope ideally -> 1 no (assuming in g&s you did not say no allocation to be used), 2 two input paths but also double counting as this is what no allocation does 3 any place where more than one product appear.

Success!

edit: to not complicate things further, I left the system expansion / avoid allocation options out of the discussion here; these would come first.

Answered: ecoinvent v3.11 based project update to ecoinvent v3.12

Thu, 25 Jun 2026 14:19:28 +0000

Can you tell which options are not the same and which openLCA version you are using? There might be some updates of naming needed, but the guideline is in principle independent of the version. openLCA uses JSON as the exchange format for data sets (not full databases, which are stored in zolca format). Maybe in older version it was called JSON-LD export and now it is called JSON package export. But for openLCA you need in principle only zolca for full databases and JSON for process datasets or database elements like locations, flows, processes etc. This has not changed over the years and is always the same.

You can export all your own processes in JSON and re-import them into the new ecoinvent version. The only disadvantage at the moment is that after import, you have to reselect the provider from the ecoinvent database in your own processes. This will be done automatically in the future, since our IT is working on an automatic updater. But for the moment, you still have to select the new provider from 3.12 once in your own models/processes.

The screenshots need some updates, this is true. But the general procedure is the same. For the import select "never update an existing dataset". For processes it should not matter what you select here, since you only import processes that are from yourself and that do not belong to ecoinvent 3.12, so no processes will be overwritten anyway. The reason why you should select "never update an existing dataset" is that locations or flows that are inside your own processes from 3.11 do not overwrite the ones from 3.12. So this option will only add all the database elements from your project that are not yet in ecoinvent 3.12, but it will not overwrite any data like locations, flows, units that exist already in the 3.12 database.

Answered: migration from Simapro : what about the External Links ?

Thu, 25 Jun 2026 09:28:52 +0000

Hi, interesting. You can quite easily read from an excel sheet also in openLCA but there is no direct automatic migration for the SimaPro direct links to openLCA. If you want, contact us for support via the nexus contact email, thank you!

Answered: contribution tree

Thu, 25 Jun 2026 09:21:48 +0000

I think the impact is not missing but direct impact caused be the specific step. E.g. in the first step, total impact is 3.81 kg, direct impact of the castor production as first step is 1.89 kg, the difference is the supply chain below.

Answered: What's the difference between ecoinvent yearly license (Educational Single-User) and non-Nexus license?

Thu, 25 Jun 2026 09:08:47 +0000

Ok sure - these are two different things. non-Nexus licenses are all licenses that are purchased not from Nexus but from elsewhere (directly from ecoinvent e.g., or from another LCA software provider). These liceses can be perpetual or yearly, commercial or educational, ect.. A yearly license is a specific license type that gives you access to the database for exactly one year.

Linking specific providers to input flows via Python/IPC server.

Wed, 24 Jun 2026 12:58:30 +0000

I am trying to use the IPC server to build processes based on external data. I have successfully managed to import a process with input/output flows and a quantitative reference, however, I am not able to add a provider (without manually choosing one),

Is there a way to also integrate choosing a provider into my python script? So that I can produce a process with inputs, outputs, as well as chosen providers based on different conditions?

I am using openLCA2.6.1 + VS code

Thanks!

Circularity Package v3 - How to do criticality?

Wed, 24 Jun 2026 10:55:59 +0000

Dear team,

we recently purchased the v3 version of the Circularity package and just found out that the Criticality indicator is missing. Is there any quick way to import and export those those flows and characterisation factors to use them in the newer version?

Best regards

Answered: Primary Energy Indicators Calculation ecoinvent EN 15804

Tue, 23 Jun 2026 16:21:48 +0000

Which Nexus version of the EN15804 add-on are you using? In the last versions, according to the PCR, we set PERM/PENRM to zero by default from the background database, and it is PERE = PERT - PERM and PENRE = PERT - PERM.

You can also see how it is calculated when you click inside these impact categories. PERT and PENRT are always calculated from the cumulative energy demands of renewable energies (PERT) and non-renewable energies (PENRT), taking into account the lower heating values. PERE and PENRE are calculated automatically as a substraction of the total and the material use, so there is no need to model this.

The only thing you have to model by yourself (unfortunately demanded by the PCR, even though not being a real "primary energy") is PERM and PENRM with the net calorific values (lower heating values) of your product inputs. If you do not explicitly model these indicators in your own foreground, PERM and PENRM will be zero by default, and it will be PERE = PERT and PENRE = PENRT. When you place the indicators for PERM and PENRM into your own foreground models with the right net calorific values, you will see that these values will automatically count towards PERM, PENRM and that PERE, PENRE will be adjusted accordingly. The total values will stay as they are, since they are correct "real" life cycle indicators for the primary energy demands that stem from elementary exchanges with the environment like coal, gas, oil etc.

Answered: How can I find usable Product flows for raw materials like sugar or citric acid?

Mon, 22 Jun 2026 21:37:44 +0000

Yes ELCD is really outdated now (and was never really complete) - we will publish a free "core" Agribalyse database without background database, you can try this. You will need to complete the supply chains with background databases though.

SimaPro projects/processes transfer to openLCA

Tue, 16 Jun 2026 14:15:48 +0000

Hello,

We currently use SimaPro 10.2.0.2 and ecoinvent 3.11 (integrated licence). We have a lot of archived projects and a couple of active ones. Can someone explain the step by step workflow to transfer these to openLCA? When you import a csv or ILCD file into openLCA, are all custom-modelled processes also transferred? Or are only the processes from Ecoinvent imported?

Thank you for clarifying

Answered: Can I create multiple Product Systems at once?

Mon, 15 Jun 2026 16:37:45 +0000

Adding a new version that was tested to work in 2.6.1

from org.openlca.app import App
from org.openlca.app.components import ModelSelector
from org.openlca.core.matrix import ProductSystemBuilder
from org.openlca.core.model import ModelType, ProductSystem
from org.openlca.core.model.descriptors import Descriptor
from org.openlca.core.database import ProductSystemDao 
from org.openlca.core.matrix.linking  import LinkingConfig
from org.eclipse.swt.widgets import Display
from org.openlca.core.model import ProcessType


#Apparently db is global variable - maybe it comes in with import App above.
processDao = ProcessDao(db)
systemDao = ProductSystemDao(db)
methodDao = ImpactMethodDao(db)

def run(process):
    log.trace("You have entered run")
    log.trace(str(process.name))
    log.trace("Building system for " + process.name)
    linkingConfig = LinkingConfig()
    log.trace("Made a new linking config!")
    #I set this up to use default providers only. Options are
    #IGNORE, PREFER, and ONLY.
    #If you select PREFER or IGNORE you probably need the
    #next line (options are LCI_RESULT or UNIT_PROCESS):
    #linkingConfig.preferredType = ProcessType.UNIT_PROCESS
    #linkingConfig.providerLinking = DefaultProviders.ONLY
    #log.trace("Made it default providers only!")
    #dasCache=MatrixCache.createLazy(db)
    #log.trace("Got MatrixCache")
    builder = ProductSystemBuilder(db,linkingConfig)
    log.trace("Created Builder")
    system = builder.build(process)
    log.trace("Completed auto-building product system")
    ProductSystemDao(db).insert(system)
    log.trace("Inserted system into database!")

    

def main():
    log.trace("Here we go")
    processes = list(ModelSelector.multiSelect(ModelType.PROCESS))
    log.trace("You selected some processes, maybe " + str(len(processes)) + "?")
    if processes is None or len(processes) is 0:
        log.trace("No processes selected")
        return

    for descriptor in processes:
      log.trace("You have entered the for loop")
      log.trace(str(type(descriptor)))
      log.trace(str(descriptor.id))
      try:
          process = processDao.getForId(descriptor.id)
          log.trace("process was assigned")
          run(process)
      except:
          log.trace("Well something went wrong")

Display.getDefault().asyncExec(main)

Answered: Regionalized Calculation active causes negative values [ecoinvent in OPENLCA]

Fri, 12 Jun 2026 16:07:55 +0000

We think this is fixed now in openLCA 2.6.2, thank you for reporting it!

Answered: Is it possible to run a stand-alone server on MacOS?

Fri, 12 Jun 2026 12:05:13 +0000

Hello,

In the latest version of openLCA (2.6.2), it is now possible to run the stand-alone IPC server on macOS. The script is launched with /Applications/openLCA.app/Contents/Eclipse/bin/ipc-server.sh {DB_NAME}.

Kind regards,

François

Answered: Is it possible to integrate an external model into OpenLCA using a Python script?

Fri, 12 Jun 2026 09:01:35 +0000

"integrate" (i.e. bringing the other model entirely into openLCA) is difficult but you can couple both models via openLCA's IPC interface; there were quite some examples on the last and the previous openLCA conference for example, linking openLCA to GAMS, Material Simulation tools, etc.. The IPC interface is explained in the manual: https://greendelta.github.io/openLCA2-manual/scripting/index.html (then follow the various links).

Answered: Purchase EN 15804 add-on for ecoinvent license owner

Thu, 11 Jun 2026 16:11:00 +0000

Hi Marion,

my nexus colleagues can follow up tomorrow but it is not necessary to buy a new ecoinvent license for the add-on, a registered license is fully sufficient. It should work when you first add the non-Nexus license to your cart and then the add-on. But we'll check tomorrow.

Cheers

Andreas

- and you are right, the Nexus EN15804 is not the ecoivent system model

Answered: comment peux je avoir la base de données Ecoenvent

Thu, 11 Jun 2026 11:21:02 +0000

order it from Nexus ;)

Answered: Ecoinvent API support in openLCA

Thu, 11 Jun 2026 11:20:26 +0000

Yes we saw this (personally I would think it is more interesting for ecoinvent to work on the database - update and extension of datasets - than on tooling around it, but up to ecoinvent of course) - maybe I can use your question for a general question:
What would be the benefit for openLCA users to access this API in openLCA? What do you all think?

Thank you very much!

Andreas

Modelling a residue

Tue, 09 Jun 2026 19:52:33 +0000

Hi,

I am trying to model a biomass residue-to-biochar process, since my flow will involve microalgae biochar, and the biomass residue is an input that will not be listed in a registered provider. How do I model this biomass residue as an input?

Looking forward to your response, thanks

Waste water treatment process with by-product recovery - how to model in openLCA

Wed, 03 Jun 2026 13:43:11 +0000

Hi everyone,

I am new to openLCA and I am modelling an electrooxidation process for treating the aqueous phase from a thermochemical conversion (TCR) process. The sole purpose of this treatment is to purify the water so it can be discharged, it has no other use.

I have two questions:

1. Should I model this as a waste treatment process? Since the only goal is to make the water suitable for discharge, I am unsure whether I should model it as a waste treatment process (with the treated water as a negative quantitative reference output, following the ELCD convention) or as a regular unit process.

2. How to handle the ammonium sulfate recovered as a by-product? During the electrooxidation, ammonium sulfate is recovered as a valuable by-product (avoided fertiliser). In my current workflow for avoided products, I usually add them as a negative value in the inputs AND as a positive value in the outputs (I never use the "Avoided product" checkbox). Should I follow the same approach here, or is there a better way to handle this in a waste treatment process context?

Thank you in advance for any guidance!

Answered: [bug][openlca 2.6.1] Exchange amounts set to zero

Mon, 01 Jun 2026 09:28:44 +0000

I know what caused the issue. In my code, I always assigned the exchange value to the amount_formula property, regardless of whether the value was a formula/expression (string) or a numeric value (float). This worked in version 2.6.0. However, in version 2.6.1 it stopped working when a float was assigned to the amount_formula property. To make it work, I now need to either convert the number to a string before assigning it to amount_formula, or assign the float to the amount property instead.

Below I enclose the full code to reproduce the issue. The relevant part of the full code is here:

e.amount_formula = float(amount)  # doesn't work
e.amount_formula = str(amount)  # works
e.amount = float(amount)  # works

The full code:

import uuid
import olca_ipc as ipc
import olca_schema as o
from olca_schema import ProcessType

client = ipc.Client(endpoint=8080)

flow_property = client.get(o.FlowProperty, client.find(o.FlowProperty, name="Mass").id)
unit_group = client.get(o.UnitGroup, client.find(o.UnitGroup, name="Units of mass").id)
unit = [u for u in unit_group.units if u.name == "kg"][0]

ref_flow_id = str(uuid.uuid4())
ref_flow = o.Flow()
ref_flow.id = ref_flow_id
ref_flow.name = "example product"
ref_flow.flow_type = o.FlowType.PRODUCT_FLOW
ref_factor = o.FlowPropertyFactor()
ref_factor.conversion_factor = 1.0
ref_factor.flow_property = flow_property
ref_factor.is_ref_flow_property = True
ref_flow.flow_properties = [ref_factor]
client.put(ref_flow)

elementary_flow = o.Flow()
elementary_flow.id = str(uuid.uuid4())
elementary_flow.name = "example emission"
elementary_flow.flow_type = o.FlowType.ELEMENTARY_FLOW
elementary_factor = o.FlowPropertyFactor()
elementary_factor.conversion_factor = 1.0
elementary_factor.flow_property = flow_property
elementary_factor.is_ref_flow_property = True
elementary_flow.flow_properties = [elementary_factor]
client.put(elementary_flow)

def exchange(flow, amount=None, formula=None, is_input=False, is_reference=False):
    e = o.Exchange()
    e.id = str(uuid.uuid4())
    e.flow = flow
    e.unit = unit
    e.is_input = is_input
    e.is_quantitative_reference = is_reference
    if formula is not None:
        e.amount_formula = f"{formula}"
    elif amount is not None:
        e.amount_formula = float(amount)  # doesn't work
        e.amount_formula = str(amount)  # works
        e.amount = float(amount)  # works
    else:
        raise Exception('No formula or amount provided')
    return e

process = o.Process()
process.id = str(uuid.uuid4())
process.name = "example process"
process.process_type = ProcessType.UNIT_PROCESS
process.exchanges = [
    exchange(ref_flow, amount=1.0, is_reference=True),
    exchange(elementary_flow, amount=0.5, is_input=True),
    exchange(elementary_flow, formula="a * 2", is_input=True),
]
client.put(process

Answered: How to apply an ELCD treatment process to a custom waste flow

Thu, 28 May 2026 12:28:34 +0000

Hi, good question -

1, ELCD is really outdated, I would recommend to use other databases (and it seems recently some universities started teaching assigments where students are suggested to use the ELCD database - tell your professors that it is outdated and not flexible and they should better suggest other databases)

2, ELCD has, with few exceptions, only aggregated processes; these cannot be really modified, and this is another drawback of the ELCD database.

3, however, to link the process you found to your model, you need to have the "waste water untreated" flow input into your processes that has waste water in the output. It is not intuitive, this reflects old ecoinvent 2 / SimaPro logic where every product must be on the output side. Think of it as waste water treatment service (output of the treatment plant, input into your process).

Good luck!

Answered: Can openLCA Nexus directly access the ecoinvent site？

Wed, 27 May 2026 11:43:59 +0000

Correct observation, interesting questions, two answers:

Can perpetual Nexus account still have permanent access to the ecoinvent website?

Yes, we share the ecoinvent credentials with users who purchased ecoinvent from Nexus.

Can openLCA Nexus directly access the ecoinvent site？

No, Nexus and ecoinvent are two different systems, but ecoinvent shares the login details with us and we share with the clients.

Hope this helps!

Andreas

Answered: Project and parameter sets

Wed, 27 May 2026 09:54:06 +0000

Hi,

Anyone could help here?

Best regards,

Jocelyn