Page 82 - Materials Chemistry, Second Edition

L1644_C02.fm Page 59 Tuesday, October 21, 2003 3:07 PM

2.6 EXAMPLE: SCOPE DEFINITION AND INVENTORY
CALCULATION

Following the example of life-cycle assessment of the chair presented in Section
2.1.1, we will illustrate the LCA phases according to ISO 14040. According to the
steps of Section 2.3, the aim of the LCA of our chair is to know the environmental
performance of our product for comparison with those of concurrent and future
improvements. As a functional unit, we will consider the most common product the
3
chair model Tarraco 53, with a total weight of 5.3 × 10 g composed of the following
materials:

• Wood: 4852 g (frame and seat)
• Iron: 10 g (screws)
• Foam: 124 g (seat)
• Fabric: 117 g (seat)

2.6.1 SCOPE OF THE STUDY
In this case, we will consider a simplified entire life-cycle taking the raw materials
from its source as wood from pine trees, iron from ore, foam from oil and fabric
from polyamide. The simplified process flow diagram is presented in Figure 2.5.

2.6.2 INVENTORY CALCULATION
In this simplified LCA only data relative to the material and energy inputs, and
wastes, according to Figure 2.6, will be considered.
In the IA, data were collected based on existing databases obtained from

TEAM . All the input and output flows were referred to the chosen functional unit,
that is, one chair. In the allocation procedure we have considered that all the
manufacturing facilities produce only one type of chair, so all flows must be assigned
to only one product.
Let us consider an example of the calculation of environmental load assigned
to this chair. The environmental load balance will be based on the scheme presented
in Figure 2.7. Material and energy inputs and outputs associated with the manufac-
turing of the chair (1 functional unit, FU) are characterized in Table 2.3. To simplify
the application example, a condensed eco-vector containing the following environ-
mental loads is selected:

• Raw materials:
• Coal (in ground)
• Natural gas (in ground)
• Oil (in ground)
• Air emissions:
• Carbon dioxide (CO , fossil)
2
• Nitrogen oxides (NO as NO )
x
2
• Sulfur oxides (SO as SO )
2
x
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