Author Topic: ecoinvent v3 Basics: Exchanges  (Read 4789 times)

Offline pbeilschmidt

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ecoinvent v3 Basics: Exchanges
« on: November 05, 2012, 15:59 »
For those who haven't been working too much with ecoinvent datasets in the past, I will highlight some of the important elements. Today: Elementary and Intermediate Exchanges.

Intermediate exchanges (formerly also referred to as intermediate flows or process flows) according to the ecoinvent glossary (p.155) are defined as "Product, material or energy flow occurring between unit processes. Synonym: Product or waste."
So, in other words: intermediate exchanges are flows that are the output of a technical activity. They are typically flows that can be found as a reference flow (see below) of an activity (see below) or as an input flow into a unit process (see below). As such they will most likely flow within the life cycle model (not across the system boundary). The intermediate exchanges are administered in a separate group from the elementary exchanges.

Note that there is no official grouping of intermediate exchanges in ecoinvent. One could maybe use the classification (see below) of the processes that deliver these intermediate exchanges as product, but at present we have refrained from introducing an own grouping, and deliver them the same way they are provided by ecoinvent: without further grouping or structuring. Use the full text search and/or the filtering feature to browse for intermediate exchanges.

More details on intermediate exchanges can be found in the ecoinvent Overview and Methodology report (Data Quality Guidelines). For naming conventions see chapter 9.3 (p. 65/66).

Elementary exchanges (formerly also referred to as elementary flows) according to the ecoinvent glossary (p.155) are defined as "Exchange with the natural, social or economic environment. Examples: Unprocessed inputs from nature, emissions to air, water and soil, physical impacts, working hours under specified conditions".
OK, so these are the resources taken from nature (e.g. extracted from the ground) or the substances that leave the technical system and are delivered to soil, water or air. Elementary exchanges hence can be found as flows crossing the system boundary either as a direct input from nature into an activity or as a direct output from an activity to nature. The elementary exchanges are administered in a separate group from the intermediate exchanges. Elementary exchanges are the flow entries that appear in a Life Cycle Inventory (LCI) and which are subject to be used for calculation of potential environmental impacts in the LCIA step using characterization factors. Typically only elementary exchanges have characterization factors.

Regarding elementary exchanges please refer to chapter 4.1.1 (p. 19) and chapter 9.4 (pp. 66-68) of the ecoinvent Overview and Methodology report (Data Quality Guidelines).

Since there are several hundred, if not thousands, of elementary exchanges, ecoinvent has defined compartments (groups) and sub-compartments (sub-groups) for them. The master data in Umberto LCA also used these compartments/subcompartments as means of structuring. The main compartments are 'air', soil', 'water', 'natural resource'. There are three other compartments defined by ecoinvent that are at present less popular: 'direct human uptake', 'economic' and 'social' which might play a stronger role in the future.

More details on compartments/subcompartments can be found in the ecoinvent Overview and Methodology report (Data Quality Guidelines) in chapter 9.4.2 (p. 67/68).

When elementary exchanges are shown in Umberto LCA, e.g in the list of materials used in the project, in an activity dataset (process specification) or in the Search Material dialog the compartment and subcompartment are shown in square brackets behind the name of the exchange e.g "1,4-Butanediol [air/urban air close to ground]".

Post your questions as reply to this post.
« Last Edit: November 05, 2012, 16:01 by pbeilschmidt »
Peter Müller-Beilschmidt
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ifu Hamburg GmbH