1. LCA Process (review)
Define Scope
Inventory Analysis
Impact Analysis
Feedback
Improvement Analysis
Manufacture
RERP
Where RERP is the “Environmentally Responsible Product Rating”

2. Improvement Analysis (Interpretation)
Life Cycle Interpretation is the phase in which the results of the study and all choices and assumptions made during its course are evaluated in terms of soundness and robustness, and overall conclusions are drawn and recommendations made.
ISO14044 distinguishes between three different elements:
Identification of significant issues based on LCI and LCIA results
Completeness, sensitivity and consistency checks
Conclusions, limitation and recommendations
One of the main aims of Interpretation is to check the results of Inventory Analysis and Impact assessment against the Goal and Scope Definition of the study.

3. Identification of significant issues based on LCI and LCIA results
Significant inventory data such as energy, emissions, waste, etc.
Significant impact categories such as resource use, climate change, toxicity, etc.
Significant contribution from life cycle stages such as individual unit processes or whole process groups (e.g. use phase)
10.3 %
4.3 %
85.3 %
0.1 %
Typical life cycle GHG emissions of an ICE passenger car

4. Completeness, sensitivity and consistency checks
Completeness check makes sure that nothing important or relevant has been left out (e.g. through cut-off, data gaps or missing impact category). Relevance of missing elements with respect to goal and scope of study needs to be discussed
Sensitivity and uncertainty analysis studies the effect of variations in process data, boundary, allocation and modeling choices and other variables. The objective is to assess the reliability and robustness of the LCI and CLIA results.
Consistency check determines whether the assumptions, methods, models and data are consistent with goal and scope of the LCA study and with each other. Examples are consistency in data quality along a product life cycle or between different product systems - regional and temporal aspects - allocation rules and system boundaries - impact assessment

5. Conclusions, limitation and recommendations
Conclusions are based on the significant findings and their robustness.
Limitations are based the completeness, sensitivity and consistency checks.
Recommendations are based on the conclusions and their limitations.
ISO also provides guidelines on
how to report on LCA studies
how to conduct a critical review of an LCA study
Critical reviews by external experts or panels on interested parties are especially important if the LCA study is intended to be used for a comparative assertion intended to be disclosed to the public.

6. Case study: Disposable versus reusable diapers
Background:
When Proctor & Gamble (P&G) launched Pampers disposable diapers in the 1960s, it was considered to be the product breakthrough of the decade.
By the early 1990s, Pampers contributed over 18% to the company’s annual revenues.
It also became a symbol of the ‘throw-away’ society and was targeted by NGOs.
To deflect criticism, P&G commissioned Arthur D. Little to conduct a Life Cycle Assessment of both types of diapers to settle the debate.
The Life Cycle Assessment:
Arthur D. Little researchers started by defining a functional unit and the resulting reference flows. They made the following simplifying assumption
The number of daily diaper changes is the same for both types of diapers.
Based on the reference flows life cycle inventories for both product systems were calculated. The following assumption was made:
90% of all reusable diapers are laundered at home.
Source: World Resources Institute, 1994

7. Case study: Disposable versus reusable diapers
Raw cotton
Cotton fabric
Reusable diaper
Diaper
use
Diaper
laundry
Diaper landfill
Other materials
Pulp and paper
43%
Absorbent gel
27%
LDPE film PP fabric
Disposable diaper
Diaper
use
Diaper landfill
Tapes, elastics, adhesives
23% 7%
Source: World Resources Institute, 1994

8. Case study: Disposable versus reusable diapers
Functional unit: Weekly diaper needs
Source: World Resources Institute, 1994

9. Case study: Disposable versus reusable diapers
This graph compares data from two different sources: Allen et al. (1992) which report data from a Franklin Associates Study (1992) and the World Resources Institute (WRI, 1994) which reports data from the Arthur D. Little study (1990):

10. Case study: Disposable versus reusable diapers
The results from Allen et al. are mostly higher than those from the WRI, up to a factor of 6.
The differences between disposable and reusable diapers are smaller in the Allen et al. results compared to the WRI results.
However, the general direction of the results are identical:
Reusable diapers consume more energy and more water
consume less raw materials
generate more emissions to air and water
generate less waste
Summary:
Many environmental choices are about trade-offs between different types of burdens
Without impact assessment these burdens are very difficult to compare
Without common methodology LCA results are very difficult to reproduce
LCA results without comprehensive documentation are not very useful
LCA methodology has come a long way since the early 1990s

11. Life Cycle Assessment of Disposable and Reusable Nappies in the UK
(UK’s EPA)
Commissioner:
Environmental Resources Management
(Simon Aumônier, Michael Collins)
LCA practitioner:
Goal:
Compile life cycle inventory and compare potential environmental impacts of production, use and disposal of reusable and disposable nappies
Scope:
Temporal coverage:
Allocation: Physical relationship, economic for retail energy use
Cut-off: Capital equipment and human labor excluded

12. Life Cycle Assessment of Disposable and Reusable Nappies in the UK
Functional unit:
The use of nappies during the first 2.5 years of a child’s life,
in the UK, for the period
Reference flows:
4.16 disposable nappies of 44.6g daily over 2.5 years
47.5 reusable nappies
Impact categories:
CML 2000 mid-point indicators
global warming
• ozone depletion
• photo-oxidant formation
• depletion of abiotic resources
• eutrophication
• acidification
• human, aquatic and terrestrial toxicity

13. Process flow diagram disposable nappies

14. Process flow diagram home laundered reusable nappies

15. Process flow diagram commercially laundered reusable nappies

16. Life Cycle Assessment of Disposable and Reusable Nappies in the UK
Home laundered reusable
Commercially laundered reusable
Abiotic resource depletion (kg Sb eq)
4.82
4.09
5.76
Acidification (kg SO2 eq)
3.78
3.13
3.05
Eutrophication (kg PO4 eq)
0.338
0.334
0.275
Global warming (GWP100) (kg CO2 eq)
626
559
762
Ozone layer depletion (ODP) (kg CFC-11 eq)
Photochemical oxidation (kg C2H2)
0.174
0.048
0.049
Human toxicity (kg 1,4-DB eq)
49.4
132
123
Fresh water aquatic ecotox. (kg 1,4-DB eq)
7.01
11.4
11.6
Terrestrial. ecotoxicity (kg 1,4-DB eq)
1.92
1.53
2.7

17. Life Cycle Assessment of Disposable and Reusable Nappies in the UK
Normalization factor: Total estimated impact of Western Europe in 1995

18. Life Cycle Assessment of Disposable and Reusable Nappies in the UK
Sensitivity Analysis
Number of changes
Excreta as putrescible waste
Omitted materials
Equivalent COD and BOD emissions
Percentage of tumble drying
Average age of washing machines
Number of reusable nappies

19. Life Cycle Assessment of Disposable and Reusable Nappies in the UK
Conclusions
There is no significant difference between any of the environmental impacts of the disposable, home use reusable and commercial laundry systems that were assessed.
Main sources of environmental impact:
Disposables:
Reusables:
Raw material production and conversion of nappy components
Fuels and electricity used in washing and drying
Waste management:
No substantial contribution to total impact
Main opportunities for improvement:
Disposables:
Reusables:
Mass reduction and improved materials manufacturing
Increase energy efficiency of washing and drying

20. The Use of Life Cycle Assessments
LCA:
Goal & Scope
Life Cycle Inventory
Impact Assessment
Interpretation
Who are the users?
What are the uses?

21. The Users of Life Cycle Assessments
Companies: Especially in Scandinavian countries, Japan, Holland, Germany, Switzerland (e.g. Volvo, Electrolux, Honda, Toyota, Proctor & Gamble, Unilever, Corus, Arcelor, Alcan, etc.) Through in-house experts, LCA consultancies or universities.
Trade associations: Especially for material commodities (e.g. plastics, steel, aluminum, concrete, etc.) Through the experts of their member companies, LCA consultancies or universities.
NGOs: Mostly commissioned to external LCA consultancies or universities.
Government agencies: Especially in Scandinavian countries, Japan, Holland, Germany, Switzerland, EU Through in-house experts, LCA consultancies or universities.
Business analysts: Typically analyze externally created LCA information on businesses and sectors.

22. The Uses of Life Cycle Assessments
Companies: Originally intended for external use, e.g. marketing. However, currently mainly for internal use due to bad initial experiences of external uses. Currently mainly retrospective and for learning proposes,
instead of prospective use for decision making purposes. Currently, decisions based on LCA results are more operational than strategic.
Trade associations: Trade associations of material commodities producers more frequently use LCA for external purposes (e.g. marketing, as lobbying tool in the policy process).
NGOs: To create scientific foundations of campaigns or investigate claims by industry.
Government agencies: To analyze and design environmental policies and regulations (especially by the EPAs of European countries). EUs Integrated Product Policy recommends LCA.
Business analysts: To analyze and rate individual companies and industry sectors.

23. Internal vs. external use of Life Cycle Assessments
Most companies currently use LCA for internal purposes.
Internal uses are:
Hotspot analysis of existing or planed products
Compare existing products with products under development
Product/process design (short-term, operational)
Product/process development (long-term, strategic)
As LCA methodology matures, so do the number and frequency of external uses .
External uses are:
Marketing, especially final product comparisons (credibility and complexity issues)
Lobbying, especially commodity comparisons
Providing information and education to customers and other stakeholders
Eco-labeling (also called environmental product declarations – EPDs)