Last post, we described how LCA models are built from unit processes, and demonstrated how the end of life scenarios for facial tissues is constructed from the following 4 unit processes from the Ecoinvent database:
- Disposal, paper, 11.2% water, to sanitary landfill/ CH U
- Disposal, paper, 11.2% water, to municipal incineration/ CH U
- Disposal, polyethylene, 0.4% water, to sanitary landfill/ CH U
- Disposal, polyethylene, 0.4% water, to municipal incinerator/ CH U
Each of the unit processes has a CH at the end of them. That is the country abbreviation for Switzerland, the country where most of the Ecoinvent data was developed. Although the facial tissues we are modeling in this LCA were manufactured in Canada and used and disposed of in the U.S., the majority of the unit processes are from European (RER), Swiss (CH), and German (DE) data from the Ecoinvent database. Why not use Canadian or American unit processes? Most of the LCA research has been conducted in Europe, and still, some of the most comprehensive and reliable LCA databases are primarily based on European data. However, it is likely that Swiss landfills and incinerators are quite similar to American landfills and incinerators, making the lack of geographically relevant data less important. The description of the role of geographic relevance to this LCA can be found in Section 2.2.2 Assumption, in the full LCA.
Using European data to model manufacturing in the developing world is more likely to result in inaccuracies in the model. The handkerchief we modeled in this LCA was manufactured in China. Luckily, the textile manufacturing unit processes available in Ecoinvent were from global (GLO) data, with approximately 70% of the manufacturing unit processes from Chinese data and 30% from European or American data. This well represents the location of production (China), while also modeling for the possibility that some upstream manufacturing steps occurred elsewhere.
The other acronym used in the unit processes listed above is U – which stands for unit process in the Ecoinvent database.
The next post in this series will focus on the model used to transform all the input data into data on environmental effects and impacts – the Life Cycle Impact Assessment.