## problem comparison of 2 productsystems in a project

lbhsa
Posts: 13
Joined: 12 Apr 2013 13:47

### problem comparison of 2 productsystems in a project

Dear all,
maybe somebody has had similar experience with the following issue:
I want to compare two productsystems in a project with IPCC2007. I first let openLCA calculate the productsystems respectively and the results are for PS1: 22.8 kg CO2-Equ. and for PS2: 22.94 kg CO2-Equ. Now when I want to compare the two PS in a project, also using IPCC2007 I get the following results: PS1 (the "better" one) is scaled to 100% and PS2 (with more impact) is scaled to about 2%. How can that be? Do I misunderstand something?
I'm using openLCA 1.3.3 on Windows 7 Professional 64Bit.
Thank you for any hint.

lbhsa
Posts: 13
Joined: 12 Apr 2013 13:47

### Re: problem comparison of 2 productsystems in a project

Dear all,
another problem occurred in one of my product systems:
A process of mine has an output of 50kg product A. I only need the results for 1kg product A (for comparison reasons) and so I recalled the data for 1 kg by connect the process to a following process that needs 1 kg of product A (and not 50!) and puts out 1kg of product A. So this second process I only use for recalling 1kg of the product.
Now the thing is, the environmental influences calculated by IPCC2007 for 50kg and 1kg of product A (I produced two product systems with the processes output of 50kg and 1kg respectively) are exactly the same. I thought openLCA would scale amounts down automatically?

aciroth
Posts: 750
Joined: 09 May 2010 23:28

### Re: problem comparison of 2 productsystems in a project

Hi Louisa,
yes openLCA does scale processes in a product system automatically. A process p1 with an output product of 50kg that is input to another process p2 that only needs 1 kg (and has no other connections to the product system) is considered with a "scaling factor" of 0.02 (=1/50). if however the next process p2 has a product with amount 1 kg, and the product system is calculated for 50 kg, then the overall factor for p1 becomes again 1/50*50 = 1.
Regarding your calculation results, did you save? If not, the changed values are not taking effect obviously.
Best wishes,
Andreas

- edition, to your project question: Projects were a bit "forgotten" in openLCA < 1.4; we mostly exported the product system results to excel and made comparisons there. Only in version 1.4 we have now a better implementation of projects which allows you to select also parameters and perform sensitivity analyses. Results in olca 1.3.3 should be ok though, you need to calculate save the processes in a product system, refresh the product systems (the yellow arrows, alternatively, you can close and reopen), and then calculate them.

lbhsa
Posts: 13
Joined: 12 Apr 2013 13:47

### Re: problem comparison of 2 productsystems in a project

What do you mean by "product system calculated for 50kg"? Would that be the reference amount under the spreadsheet "general information"?
Thanks

aciroth
Posts: 750
Joined: 09 May 2010 23:28

### Re: problem comparison of 2 productsystems in a project

yes exactly, the reference amount for the product system.

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