Parameters

[Drugojacopo]

Dear all,

I could not find this in the documentation: how do you recall/influence the parameters in a process from the parameters in a product system?

To make an easy example: I have a process for road transport which uses as parameter the distance in km. If I don't use the parameters in the Product System, what happens is that if I modify the value in the process, then this is changed in every Product System sharing that process, which basically makes the use of a parameter pointless. My problem is that I have not been able to link the product system parameters to the process parameter so that I can change it only in one specific system.

Any help is appreciated!

Regards,

Jacopo

[aciroth]

Dear Jacopo,

In order to "influence" the parameter on the product system level, you need to have the same parameter / a parameter with exactly the same name on the product system level. Then, you can specify a value for the parameter on the product system level, and if you then set in preferences the direction as "top down", then the product system parameter value will overwrite the value for this parameter on the process level. You can further add global parameters that overwrite then parameters that have the same name also on the product system level.

Hope that helps!
Andreas

parameters.png (22.1 KiB) Viewed 8011 times

[lbhsa]

Hi,
I have some questions on parameters which could be interesting for other users, too:
I am working on adding parameters to my product system in order to be able to calculate the impacts of different numbers of items. I wanted to do that the follwoing way: in the respective product system in the spreadsheet "parameter" I added a parameter meant to be changed for different quantities. After, I want to go into the individual processes and change (where necessary) in the field "resulting amount" a number to the parameter with the same name I entered in the product system. Thing is, with some processes I cannot enter the parameters name under "resulting amount", but get an error message saying: "Evaluation of expression p0 failed". What could be the reason for that?

Also I wanted to add the parameter p0 under the "reference quantity" (spreadsheet "General information"), but this also is not accepted by openLCA. Why is that? I think entering a parameter into that "reference quantity"-field is only consequential when using parameter within a prod.sys., isn't it?

And if I change under "preferences/global parameters" to "top down" after choosing a database, is that parameter going to overwrite all parameters in the whole prod.sys. which have the same name? Consequently, if I later add a new process that hasn't anything to do with my one prod.sys., used parameters in that process can automatically not have the same name like the one parameter defined under "preferences", right? Formulated better: can one name of a parameter only be used once, i.e. in one process? I think the answer is yes, but just to assure me.

Thanks a lot!

[aciroth]

Hi,

I want to go into the individual processes and change (where necessary) in the field "resulting amount" a number to the parameter with the same name I entered in the product system.

You can do this by adding a parameter with the same name that you use in a product system, for the process, and give the parameter a value there, at process level, too

I wanted to add the parameter p0 under the "reference quantity" (spreadsheet "General information")

The reference quantity just specifies the reference flow (at the general information tab), for processes; you can apply a parameter on the input/output sheet. For product systems, the target amount is the quantitative reference which should not be parameterised but fix (I think).

can one name of a parameter only be used once, i.e. in one process?

No, one parameter name can be used in many different processes, for example payload in truck data sets, with different values, but indeed, when these processes are used in one product system which has the same parameter the process-parameters will all be set to the same value of the product system.

Hope this is clear?
Andreas

[lbhsa]

Hi again,
almost clear. Just to make sure I really got it absolutely right: Say, I have a product system with an introduced parameter p0, having the current value of 1000 pieces. In one process (P1) of the prod.sys. I introduce a parameter also named p0 and set the value here to 1000. This process P1 of my prod.sys. has an output that is passed through the whole prod.sys. to the final life phase. Having modelled the system like that and changing the quantity in the product system to 5000 pieces now, I would expect the product system to forward this changed value (50001000) to the respective process(es) P1. Thing is, I tried exactly this case and the calculated (simple) result tells me that on the output side of the inventory analysis, there are left 1000 pieces (and not 5000!) of the reference flow of the process P1.
Or does this forwarding from product system to processes only work when the global parameters under “Preferences” are applied? Because this neither doesn’t work when trying to apply it (error message:”error while changing parameters. Changes can not be saved”).
Thanks a lot!

[aciroth]

Hm, can you maybe post your example here (as a screenshot) - e.g., if the parameter is only affecting the product of one process than it has exactly the opposite behaviour of what you describe.
Thanks!
Andreas