Environment
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Oil Point example: "Sweaters"
In this example, two sweaters of different materials are
compared using the Oil Point Method. The sweater materials are "pure
primary PET" (polyester) and "pure cotton".
The comparison is done in three steps: 1. Focus, 2. Evaluate
and 3. Interpret.
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1.
Focus |
FUNCTIONAL UNIT
The Functional Unit, or "service", can be defined as "Provision
of a clean, non-coloured knitted sweater of 1 kg weight, to be used washed
and tumble-dried 75 times in Denmark".
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2. Evaluate
(PET sweater)
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|
OP/kg |
OP/product |
Material:
1.2 kg (processing)
|
1.3 |
1.56 |
Manufacturing:
1 kg yarn & knitting |
2.8
|
2.8
|
Transport:
1 kg* 1000 km
= 1 tkm |
0.01
OP/tkm |
0.01 |
Use:
75 x
- washing at 60 C,
- light drying,
- detergent |
0.05
0.15
0.012 |
3.75
11.25
0.9 |
End-of-life:
inciner., 0.75 kg
landfill, 0.25 kg |
0.9
0 |
0.675
0 |
Total:
Total per year:
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18.2
6.1
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2. Evaluate
(Cotton sweater) |
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OP/kg |
OP/product |
Material:
1.2 kg
processing
feedstock
|
0.6
-0.1 |
0.72
-0.12 |
Manufacturing:
yarn, knitting & cleaning |
4.4
|
4.4
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Transport:
1 kg* 1000 km
= 1 tkm
|
0.01
OP/tkm |
0.01 |
Use:
75 x
- washing at 60 C
- intensive drying
- detergent |
0.05
0.2
0.012 |
3.75
15
0.9 |
End-of-life:
inciner., 0.75 kg
landfill, 0.25 kg |
0.1
0 |
0.075
0 |
Total:
Total per year:
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|
24.7
8.3 |
Results: The cotton sweater scores about one and a half times as many Oil
Points as the PET sweater. The highest impact in both alternatives results
from the tumble-drying in the use stage. Here, cotton requires more intensive
drying, probably due to its higher capacity to absorb water. |
3. Interprete |
UNCERTAINTIES
Uncertain are the processes in the stages transport, use and end-of.life.
Neither transport nor end-of-life processes have significant influence
on the overall result. In the use stage, however, natural drying instead
of tumble-drying would lead to a more or less equal environmental performance
of cotton and PET.
HOLISTIC CONTEXT
Seen in a holistic perspective, even minor improvements would make sense
as sweaters are mass products. Most influencial, however, is the use pattern
of the owner.
IMPROVEMENT POTENTIALS
Improvement potentials lie primarily in the washing and drying properties
of the sweaters. For example, fibres could be treated in order to absorb
less water. More challenging would be to rethink the use situation of
the sweaters. Why are they washed every second week? Is it possible to
stimulate the user to wash the sweater with longer intervals, e.g. by
changing the design?
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References |
Details on the example:
Niki Bey: "The Oil Point Method",
2000
Links:
Zanussi Denmark
National Concumer Agency of Denmark
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Image
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Thomas Nissen
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Copyright |
© 2001 Torben Lenau, Niki Bey
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