Page 57 - Materials Chemistry, Second Edition

2.2 Scope 41

(humidity) or in the living room (well-being, at least in northern latitudes without
floor heating), their application is nearly exclusive.
Different cleaning requirements can be integrated into the fU and be quantified
in the use phase of LCI analysis. If, however, experience shows that the coverings
require practically the same care, the use phase, within comparative studies, can
be treated as black box and be excluded from comparison (see Section 2.2.1).
However, omission of a life cycle stage is not recommended in principle because
an optimisation analysis that may follow is based on incomplete information:
perhaps the most important part of the life cycle was omitted. Who can say, without
applying LCA, whether the care of a floor covering over 30 a requires more or
less energy or raw materials, and so on, than the floor covering production, the
installation or the disposal? If only bad data are available, at least an estimation
of the omitted life cycle section should be attempted. If within the goal definition,
product optimisation has the highest priority, a life cycle stage must not be omitted,
under any circumstances.
Genuine added value is not easily traceable in the simple examples of beverage
packaging and floor coverings. Here, the qualitative description in the comparative
discussion of the results is usually sufficient. Should an energy recovery occur
within a variant with heating value, it can be considered as bonus in the Inventory
Analysis; not every small difference of performance needs to be considered by
system expansion (see Section 3.3).

2.2.5.3 Procedure for Non-negligible Added Value
In some system comparisons, one of the regarded systems show a substantial added
value that has to be taken into consideration and accordingly to be assessed. 31)
As has already been mentioned, ‘Products’ in ISO language are both goods and
services. An important application field of LCA is the comparison of different
options for waste management services (LCAs in waste management).
Within a comparison of different waste disposal methods (fU = disposal of a
certain mass, e.g. 1 ton of domestic waste), thermal disposal with energy generation
supplies a quantity of electricity and/or steam and/or hot water that corresponds
to the calorific value of the waste (× efficiency of energy conversion). With disposal
by landfilling, however, only in the most favourable cases a part of the dump gas
can be collected and used energetically (see Figure 2.5). In Germany, this applies
to old facilities only, because landfilling of domestic waste is just permitted after
pre-treatment (e.g. thermal).
To adequately compare both systems, the fU must be extended. It then reads as
follows (for example):
fU = disposal of a given mass of domestic waste plus supply of energy
(reference flow ∶ 1t + x MJ energy)

This fU is fulfilled by system A (thermal disposal with energy recovery) in
Figure 2.5, whereby a characteristic number not specified here may characterise

31) Fleischer and Schmidt (1996).