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© 2 0
1 3 L M A S
c o n
t a c
t e m a
i l :
Framework for Modeling the Uncertainty of Future Events in Life Cycle Assessment
Y i - F e n
C h e n a n
d R a c
h e
l S i m o n
y i f e n c
h e n @
b e r k e
l e y . e
d u
r a c
h e
l r i f i c @
g m a
i l . c o m
Funding Sources: LMAS
Objectives Rethinking LCA
Model Framework: Rethinking LCA Case Study -- Laptop
Probability of Recession Tablet Impact on PC usage
Case Study Results Conclusion and Future Work
■ A model framework is proposed to incorporate the futureuncertainty.
■ The model provides additional information about the possiblerange of the values that the carbon footprint will likely take.
■ Case study on laptop shows the impacts of including suchuncertainty has the potential to alter the LCA resultsignificantly.
■ More and better quality data may be required for betterprobability estimation of events.
■ Future work: construct a database for identifying events andtheir probabilities.
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5
k g C O 2
‐ E q u i v .
Cumulative Global Warming Potential (100 years) for a Dell Latitude E6400 laptop
Use EOLManufacturing
Assembly &
Transport
Time (years)
Guaranteed Emissions
Actual Emissions Point When LCA
is Conducted
Scenario 3
Scenario 2
Scenario 1Baseline
2009
2012
Year 0 Year 1 Ye ar 2 Ye ar 3 Ye ar 4 Ye ar 5
2013 2014 2015 2016 20172012
2010 2011 2012 2013 20142009
Complementary (Certain)
ComplementaryRecession
Recession
0.00 50.00 100.00 150.00
CO2e in Use Phase (kg)
S c e n a r i o s
■ With the inclusion of uncertain events,
■ Use phase greenhouse gas emissions are up to 40% lower than the
benchmark scenario
■ 32% to the overall LCA emissions reported by O’Connell and Stutz
(2010) as opposed to their estimates of 47%.
0
5
10
15
20
25
30
35
40
1 2 3 4 5
k g C O 2
‐ E q u i v .
Year
Use Phase Global Warming Potential (100 years) for a Dell Latitude E6400 laptop
RecessionNew Complementary
Product
Chance of
a Recession
Occurring When People Begin
Replacing Their Devices (third year of consideration on,
in the U.S.)
0
0.002
0.004
0.006
0.008
0.01
0.012
1 7 1 3
1 9
2 5
3 1
3 7
4 3
4 9
5 5
6 1
6 7
7 3
7 9
8 5
9 1
9 7
1 0 3
1 0 9
1 1 5
1 2 1
1 2 7
1 3 3
P r o b a b i l i t y D e n s i t y
Time since Last Recession
Likelihood Recessions Will Occur Given Time Since Last Recession
The National Bureau of Economic Research (NBER) Recession Indicator
significant decline in economic activity,
lasting more than a few months,
measured by:
■ Real GDP,
■ Real income,
■ Employment,
■ Industrial production, and
■ Wholesale‐retail sales
D e c ‐
1 9 6 9
O c
t ‐ 1 9 7 0
A u g ‐
1 9 7 1
J u n ‐
1 9 7 2
A p r ‐
1 9 7 3
F e
b ‐
1 9 7 4
D e c ‐
1 9 7 4
O c
t ‐ 1 9 7 5
A u g ‐
1 9 7 6
J u n ‐
1 9 7 7
A p r ‐
1 9 7 8
F e
b ‐
1 9 7 9
D e c ‐
1 9 7 9
O c
t ‐ 1 9 8 0
A u g ‐
1 9 8 1
J u n ‐
1 9 8 2
A p r ‐
1 9 8 3
F e
b ‐
1 9 8 4
D e c ‐
1 9 8 4
O c
t ‐ 1 9 8 5
A u g ‐
1 9 8 6
J u n ‐
1 9 8 7
A p r ‐
1 9 8 8
F e
b ‐
1 9 8 9
D e c ‐
1 9 8 9
O c
t ‐ 1 9 9 0
A u g ‐
1 9 9 1
J u n ‐
1 9 9 2
A p r ‐
1 9 9 3
F e
b ‐
1 9 9 4
D e c ‐
1 9 9 4
O c
t ‐ 1 9 9 5
A u g ‐
1 9 9 6
J u n ‐
1 9 9 7
A p r ‐
1 9 9 8
F e
b ‐
1 9 9 9
D e c ‐
1 9 9 9
O c
t ‐ 2 0 0 0
A u g ‐
2 0 0 1
J u n ‐
2 0 0 2
A p r ‐
2 0 0 3
F e
b ‐
2 0 0 4
D e c ‐
2 0 0 4
O c
t ‐ 2 0 0 5
A u g ‐
2 0 0 6
J u n ‐
2 0 0 7
A p r ‐
2 0 0 8
F e
b ‐
2 0 0 9
D e c ‐
2 0 0 9
O c
t ‐ 2 0 1 0
A u g ‐
2 0 1 1
J u n ‐
2 0 1 2
U.S. Recessions over Time
Time Intervals between Events Fitted To Weibull Distribution
■ LCA may provide non-significant result if uncertainty is notincluded.
■ A model framework is proposed to incorporate the uncertaintyof future events into LCA.
■ Traditional thinking of LCA:
0
50
100
150
200
Manufacturing
& Assembly
Transport to
customer
Use Recycling
(75%)
k g C O 2
‐ E q u i v .
Life Cycle Phase
Global Warming Potential (100 years) for a Dell Latitude E6400 laptop
Concept for Event Adjusted LCA
1. Identify events
2. Determine probability over period
3. Evaluate impacts
4. Incorporate into LCA
UseManufacturing
Assembly &
Transport
Time (years)
Guaranteed Emissions
Use EOL
Time (years)1 2 3 4 5
Expected Emissions ∑ Baseline Emissions) ‐ ∑ Impact ∗Probability
E1
E3
E2
■ Carbon footprint of
the use phase of laptop issignificant.
■ Two events areconsidered in the
case study.■ Recession
■ Complementary Technology
■ Two scenarioswith uncertaintyare analyzed.
Events occur change the trajectory of actual
emission
Rethinking of LCA
■ As a new complementary technology, surveys suggested that
users who own both a tablet and a PC reduce their use time onold PCs for content consumption activities. [Morgan Stanley,2010]
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
2 0 0 9
2 0 1 0
2 0 1 1
2 0 1 2
2 0 1 3
2 0 1 4
2 0 1 5
2 0 1 6
2 0 1 7
2 0 1 8
2 0 1 9
2 0 2 0
2 0 2 1
2 0 2 2
2 0 2 3
2 0 2 4
Number of Adopters
Cummulative Number of
Adopters
Proportion of people own both device
× the average reduced usage time of each user
1 2 3 4
k g C O 2
‐ E q u i v .
Year
