Unit processes and cumulative results LCI

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fro
Posts: 6
Joined: 13 Jul 2012 13:58

Unit processes and cumulative results LCI

Post by fro » 16 Jul 2012 08:56

Hello,

I have developed a rough LCA model with openLCA and have a few questions. I'm still a bit confused between unit processes and cumulative results. Unit processes are used for developing a model. However, after in the inventory of product system only cumulative results are seen (as elementary flows). For example, if I want to know the raw materials composition of my system, are these represented by elementary flows (e.g. resource/ in ground) or...?
Another question, when I develop my own process (inputs represented by various product flows) and I don't create extra cumulative results LCI. Is it OK to do this way?
I hope I was clear enough to explain my issue.

Thanks

fro
Posts: 6
Joined: 13 Jul 2012 13:58

Re: Unit processes and cumulative results LCI

Post by fro » 01 Aug 2012 08:36

Hi,

couldn't anybody give a quick answer? In brief, how can I see from life cycle inventory composition of my product system in terms of amount of Aluminum, copper, glass, plastics, gold, etc.?..

Thanks a lot

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

Re: Unit processes and cumulative results LCI

Post by aciroth » 01 Aug 2012 16:35

Hi fro,
so, quick reply: the material composition of an investigated product is typically lost in the calculation; calculation results are, as you say, elementary flows, and these are not glass, plastics, copper, but rather copper ore and so on. You see the material composition of the product if you look into the process that is delivering this product. This process will have the materials on the input side (or, parts consisting of different materials).
You do not need to create aggregated LCIs in addition to a calculation.
Hope this helps!
Andreas

fro
Posts: 6
Joined: 13 Jul 2012 13:58

Re: Unit processes and cumulative results LCI

Post by fro » 02 Aug 2012 12:58

Thanks a lot, it was very helpful! I couldn't find material composition and decided to ask, in case this information was hidden somewhere..
Yes, I could obtain material inputs from the processes (this option also looks like the only possibility). However, this brings some uncertainty as usually during the production process some waste is produced and unused raw materials.. And this (manual) approach is very time consuming especially in complex product systems.

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