Life cycle assessment (LCA) aspects of concrete - Eco-efficient Concrete

Civil Engineering Reference

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a relation between the inputs, e.g. fossil fuels or minerals, and outputs,

e.g. emissions, of the LCi phase with the impacts on the environment. For

this reason, for each impact category an indicator should be chosen in the

environmental mechanism, which as far as possible represents the totality of

all impacts in the impact category. This indicator can in principle be located

at any position in the mechanism, from the LCi results down to the category

indicators. However, the environmental relevance is typically higher for

indicators chosen later in the environmental mechanism (iSo, 2003). For

example, the environmental mechanism of acidification is shown in Fig.

3.6 (iSo, 2006a). in the damage-oriented approach, the category indicator

is chosen at the endpoint of the environmental mechanism. in the problem-

oriented approach, the category indicator is chosen at an intermediate level

somewhere along the mechanism - at midpoint. Examples of category

midpoints and endpoints for some impact categories are shown in Table 3.4

(iSo, 2003).

The most famous example of damage-oriented approaches is Eco-indicator

99 methodology, developed at Pré Consultants B.v., The netherlands

(Goedkoop and Spriensma, 2001). The impact categories are defined at the

endpoint of the environmental mechanism and express the damage to Human

Health, Ecosystem Quality and resources (Table 3.5). Definitions at this level

are much easier to comprehend than the rather abstract definitions of midpoints

such as infrared radiation, Uv-B radiation or proton release. However, the

problem with this approach is in fact that it is not easy to establish a clear

relationship between the LCi results and damage categories. in the top-down

approach, it is not possible to avoid normalization, grouping and weighting.

SO x , HCl, etc.

(kg/functional unit)

LCI results

Impact