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written.
Part 3: Scientific background 34 May 2001
1.2.3.7 Software for LCA
Scientific endeavours to develop a method for LCA lead to calculation procedures involving a vast
multitude of input data. Today it is not unusual to find 500 unit processes, 600 economic flows and 1000
environmental flows in a typical LCA. Clearly, such an analysis cannot be undertaken by hand and
calculations must therefore be run on computers. There are three ways to use computers:
- One can use a general, i.e. non-LCA-dedicated program such as a spreadsheet. This has certain
advantages: most (potential) practitioners already know how to work with these programs, they are
quite flexible in manipulating data and they provide easy access to graphical presentations. On the
other hand, the open and flexible nature of these programs make them rather inefficient for this
particular purpose: the user must in fact himself create all the links between flows and processes
and the same applies to the computational algorithms.
- One can also use a dedicated LCA program. There are several dozen such programs available,
ranging in price from free to many thousands of euros and in scope from very basic to quite
advanced. Many commercial programs are shipped with a database of process data and/or Impact
assessment data. A clear disadvantage of commercial software is that the user has no capacity to
perform analyses deviating, however slightly, from those that are part of the program. Some
programs cannot deal with allocation, while others can handle one allocation method only. There is
currently no program available that provides for full implementation of all the methods specified in
this Guide.
- As a compromise between the flexibility of spreadsheets and the power of dedicated programs, a
practitioner may decide to develop his own LCA software. This is a major task. This is clearly not an
option to be recommended as standard practice.
For the occasional practitioner dealing with very small product systems (say, less than 20 unit
processes) we tend to recommend the use of spreadsheets. As product systems grow or if detailed
analyses are required, including sensitivity and uncertainty analyses, for instance, the use of
commercial software is advisable. We refer to Rice (1996), Rice et al. (1997), Menke et al. (1996) and
Siegenthaler et al. (1997) for an overview of the programs then available1.
 
1 A program that is intended mainly for educational purposes has been developed at CML. It can be
downloaded, for educational purposes for free, at: http://www.leidenuniv.nl/interfac/cml/ssp/cmlca.
1.3 Management of LCA projects: procedures
1.3.1 Introduction
In principle, an LCA is an analytical activity that should be performed by independent experts. However,
LCA projects also generally involve using the analytical results within a policy or strategy framework, as
is the case with the majority of LCA studies conducted or commissioned by public authorities or private
companies. In these cases the results of the LCA will have an influence on government or corporate
decision-making and we then speak of mandated science: a scientific, analytical activity is performed for
which a mandate has been given, and the outcome may steer decision-making.
Authoritativeness of results
ISO 14040 defines an interested party as “an individual or group concerned about or affected by the
environmental performance of a product system or by the results of an LCA”. While retaining this
definition, in this Guide we generally employ the shorter synonym ‘stakeholder’. Three groups of
environmental stakeholders are usually recognised: political (national, international legislators), public
(press/media, local environmental initiatives and consumer and environmental organisations) and market
(competitors, customers, suppliers and financial institutions).
When LCA is applied as mandated science problems of authoritativeness often arise, that is to say: the
outcome of the LCA may not always be accepted by all the stakeholders in the policy or strategy. The
upshot will be clear: if the outcome if not accepted, the LCA will be of no influence on decision-making.
Problems of authoritativeness may arise for one of three reasons:
- the actual results of the LCA may be debatable, owing to dubious assumptions, data and/or system
boundaries being used, for example;
Part 3: Scientific background 35 May 2001
- there may be a misfit between the LCA results and other considerations pertinent to decision-
making (safety, cost-effectiveness, etc.);
- the policy/strategy setting often involves many different parties representing differing interests. In
such cases, parties will endeavour to magnify the above objections, for reasons of strategy as well
as substance.
Conducting LCAs in accordance with ISO standards
If an LCA project is performed according to ISO standards, this means not only that the LCA itself will
be methodically structured but also that certain aspects of the LCA process will be established
beforehand. There are two important issues here. First, the ISO standards lay down (quality) criteria for
the design and execution of the LCA as such as well as for the reporting of results, data, methods,
assumptions and limitations. Second, the ISO standards outline a procedure for a ‘critical review’. In
general terms, the ISO standards deem a critical review optional and indicate that use can be made of
different review options. If the LCA results are used to support ‘comparative assertions’ a critical review
is mandatory ("since this application is likely to affect interested parties that are external to the LCA
study") according to § 7.2 of ISO 14040. In cases involving “a comparative assertion that is disclosed to
the public” a “review by interested parties” is required under ISO 14040 (clause 5.1).
For the sake of clarity, we here define several other key terms used in this Guide. An ‘LCA study’ is an
environmental study in which LCA methodology is employed, performed by practitioners who may or
may not be affiliated to the party or parties commissioning the study. An ‘LCA project‘ is a project that
seeks to obtain particular results by means of an LCA study. Besides commissioning parties and
practitioners, the project may also involve other organizations and individuals, in the capacity of data
supplier, peer reviewer or interest group, for example. An ‘LCA process’ is the integral series of
exchanges among the individuals and organisations participating in an LCA project, from project
initiation and guidance through to interpretation and discussion of the results.
Use of a process approach
Against this background, LCA-based decision-making can be seen as a process designed to involve all
relevant stakeholders, which may take a variety of forms. This implies a need to elaborate a process
approach, with the process being designed as appropriately as possible for the specific nature of this
kind of decision-making and the various specific situations that may be involved. If a process approach is
successfully implemented, the process result (i.e. the outcome of such an approach) will show a
number of characteristics.
process result
support
substantially
robust
developed in
a fair process
Figure 1.3.1.1: Result of the process approach (De Bruijn et al., 1998)
In the first place, there will be due support for process result. Having exerted an influence on the results,
the various stakeholders will often come to hold different (‘richer’) views. Second, the process result will
be substantially robust. That is to say: the outcome will be scientifically so well underpinned as to stand
up to criticism. The stakeholders will have contributed their know-how and information and enriched the
results with their knowledge and values, with due allowance being made as far as possible for the
dynamics of new developments, innovation and so on. Third, the process will have been fair. All the
Part 3: Scientific background