A rigorous LCA has to be made according to the ISO 14040 series
(especially 14044: 2006). A new Handbook on Life Cycle Assessment of the EU
(see tab data > references 7.1) provides the "translation" of
these ISO definitions in a comprehensive guide for experts
This webpage is not meant to replace this Handbook, but gives a general introduction on the subject for non-specialists so they will understand the main principles. A practical guide for non-specialist is available at www.vssd.nl/hlf/b018.htm
some (simplified) definitions, see slide
8.1a . Three aspects of these definitions are important:
- the difference between LCI and LCA
- the difference between LCA and LCC
- how to deal with "from cradle to gave" in real life calculations
An LCI is not more and not less than a mass balance and an energy
balance, as it is common practice (already for many decennia) in chemical
engineering. Essential is a choice of proper boundary limits of the system
which is studied.
An LCA is the analyses and the interpretation of the LCI in terms of environmental impact. The LCA method comprises 4 steps, slide 8.1b .
An LCI of a total system is, in most of the cases, the sum of LCIs of subsystems. The last step of an LCA, the interpretation, must always be done on the basis of "from cradle to grave", so the LCI of the total system must comprise the total life cycle chain "from cradle to grave".
This issue appears to be confusing for people who start with the LCA method in practice, since most data from databases are of LCIs and LCA's of subsystems (not from cradle to grave). Most of the data on materials and products are given for "from cradle to finished material or product". Separate data are available for the subsequent steps of the life cycle chain (e.g. use phase and End of Life phase). So databases provide components (subsystems) of the total system, which have to be combined carefully to construct the total system.
Another confusing aspect for people who start with LCA is how
to deal with impact assessment (step 3 of LCA). Impact assessment is about
creating one or more general indicators for environmental impacts. A decennium
ago it was assumed that the end result of the assessment step could only be
a set of indicators. Now it is generally accepted that a single indicator
for LCA is preferable.
As such this is an extremely complex issue, and therefore it is a field of debate for specialised scientist only. For LCA practitioners it is not necessary to know all the details. It is only necessary to select one of the many models of impact assessment. At the Delft University of Technology we apply either the eco-indicator 99 (a damage based model), or the eco-costs 2007 (a prevention based model). Such a model transfers the LCI data in one single indicator for LCA.
The road to a single indicator ("impact assessment" step 3) is defined in 5 subsequent steps:
a. classification = making groups of emissions for each type of impact category
... (e.g. global warming , acidification, etc.)
b. characterisation = creating "equivalent" emissions per type of impact category
.... by taking into account the relative impact of each emission (resulting in kg CO2 equivalent, etc.)
c. normalisation = comparing the equivalent emissions to the total emissions of that class in the EU;
....In monetary systems normalisation results in the relative importance,
... which is determined by the "marginal" economic costs (of damage or prevention)
(d. grouping = bundling of impact categories to final damage groups, the so called endpoints)
e. weighting = adding the relative importance by a panel of experts
...Note: in monetary systems step d. and e. are not required: these parameters are set to 1
advantage of a single indicator is that there are tables available for subsystems,
which makes the impact assessment step in LCA simple (e.g. the eco-costs for
materials, products and services are given in the Ecocost 2007 LCA databases,
see under tab data).
The eco-costs database provides data in:
- SI units (kg, m2, m3, Joule, etc.), to be applied in combination with the
. classical mass balance and energy balance of LCI
- €, to be applied in combination with the calculation of costs in the total life cycle, the LCC (to assess services)
Concluding: The way LCA's are done in engineering and design is depicted in slide 8.1c .
As an example, the LCI of different types of paper (recycled from waste paper as well as paper from wood) is given in the pdf file "corrected FEFCO database 2003". This document is an excellent example how reporting on LCI must be: it provides a clear description of the system boundaries, on what has been calculated and how. Excel sheet "testliner FEFCO 2003" (testliner is 100% recycled paper) shows how the LCI data are multiplied by the appropriate impact assessment factors to arrive at eco-costs:
step 1: classification of the inputs and outputs (emissions) in impact categories
............ (global warming , acidification, etc.)
step 2: multiplication of emissions with the classification factors to arrive at the
............. "equivalent emission" of the specific impact category
step 3: making the sum of equivalent emissions for each impact category
step 4: multiply the sums of step 3 with the marginal prevention costs per impact category
step 5: calculate the sum of eco-costs
Note 1: the issues like energy and transport are directly converted to eco-costs by means of the data in the Ecocosts 2007 LCA databases
Note 2: the grouping and weighting step in the impact assessment can be skipped: in monetary systems, the normalisation step immediately gives the end result.
It is important to notice that it is easier to multiply the emissions directly by the eco-costs per kg of that emission, applying the data of the Ecocosts 2007 LCA databases. At the Delft University of Technology we call that the Fast Track LCA Method. This is explained under 'Fast track LCA' and LCA for Services (in the left blue column)..
When you have to make your own LCA, use the step by step
procedure of LCA (click 'LCA step by step' in the left blue column)