Impact Assessment and Interpretation in LCA H. Scott Matthews Research Director, Green Design Institute Associate Professor, Civil and Environmental Engineering / Engineering and Public Policy

Eco-indicator 99 method Note TRACI is conceptually similar 3 categories of endpoints: –Human Health –Ecosystem quality –Resources Damages to human health expressed as disability adjusted life years (DALYs) Damages to ecosystems expressed as percent of species lost due to env’l loading Resource constraints expressed as function of remaining reserves

Cultural Theory Model Due to uncertainties, contains embedded assumptions to make 3 damage models –Egalitarian (long term, minimal sci. evidence) –Individualist (short term, only believes proven) –Hierarchist (balanced, wants consensus)

Using DALYs Carcinogens cause some deaths per yr Death has disability rating of 1 If a type of cancer shortens life by 10 years, we say it has value of 10 DALYs –Ex: during summer smog, people treated in hospital. Treatment has rating of 0.4 on DALY scale. –If treatment lasts 0.01 yrs, each case could be weighted as DALYs

Notes Ecosystem and resource factors work in a similar way (weights) Do the example on the board using the handout of eco-indicator weights for health effects only. First, can you verify the numbers in the 2 columns of each table? Then do the weightings..

Interpretation Inventory + Impact combined Make results fit within goal and scope Double check model and analyze results Conclusions + Recommendations –e.g., “use phase/certain process is most important” Maybe iterative re-goal/re-scope based on preliminary findings –E.g. “we didn’t realize certain material would be 95% of results - need to do more to understand that material in scope”

Sample Interpretation Results Can also display as category percents -> materials prod significant

Sample Interpretation Results Similar but now grouped by processes -> Energy significant

Sample Sensitivity Analysis The 2 allocation methods suggest that you cannot really differentiate Between Options A and B.