Goal and scope definition

The goal and scope definition is the first phase in conducting the LCA study. According to the ISO 14040 and the ISO 14044, the goal and scope of an LCA study shall be clearly defined and consistent with the intended application.

Both standards underline, that the goal of an LCA study shall unambiguously state the intended application, the reasons for carrying out the study and the intended audience. One has to consider and clearly define the following items:

• The functions of the product system, or, in the case of comparative studies, the systems;

• The functional unit;

• The product system to be studied;

• The product system boundaries;

• Allocation procedures;

• Types of impact and methodology of impact assessment, and subsequent interpretation to be used;

• Data requirements;

• Assumptions;

• Limitations;

• Initial data quality requirements;

• A type of a critical review, if any;

• A type and a format of the report required for the study.

If the scope is sufficiently well defined, it will ensure that the extent, depth and the detail of the study are compatible and sufficient to address the stated goal. Nonetheless, one has to remember, that LCA is an iterative technique. Therefore, as data and information are collected, various aspects

of the scope may require modification, thus enabling to meet the intended goal. In some cases, even the goal may be changed due to the unforeseen limitations or constraints. It is important to document such changes in the goal and scope duly (EN ISO 14040:1997(E), EN ISO 14040:2006(E), EN ISO 14041:1998(E), EN ISO 14044:2006(E)).

2.5.2.1 Function and functional unit

The basic aspects to be defined in the scope of the study are the function of the product and the functional unit.

The functions of the product are related to its performance characteristics. Functional unit is a measure of the product performance (output), which primary purpose is to provide a reference to which all inputs and outputs are related. In a mathematical sense, functional unit results from a normalization of all input and output data. It shall be consistent with the goal and scope, as well as clearly defined and measurable. The secondary purpose of the functional unit is to provide a common basis to compare different LCA studies. In some cases, when the product system has multiple possible functions, the choice of the functional unit is dependent on the definition of the goal of the study (EN ISO 14040:1997(E), EN ISO 14040:2006(E), EN ISO 14041:1998(E), EN ISO 14044:2006(E)).

2.5.2.2 System boundaries, inclusion of inputs and outputs

Setting the system boundaries is of a crucial importance for performing the LCA study. This phase determines, which unit processes shall be included within the LCA. Factors determining the system boundaries are: the intended application of the study, the assumptions made, cut-off criteria, data and cost constraints, and the intended audience. Moreover, the selection of inputs and outputs, the level of aggregation within a data category, and the modelling of the system shall be consistent with the goal of the study. All criteria used in establishing the system boundaries shall be well documented (EN ISO 14040:1997(E), EN ISO 14040:2006(E)).

Nonetheless, very rarely there is enough time, data, or resources to perform such detailed LCA studies. If a decision concerning the exclusion of some unit processes or inputs/outputs has to be made, one has to clearly state and describe it. The criteria used in establishing the system boundaries usually dictate the degree of confidence in ensuring that the results of the study have not been compromised and that the goal of a given study will be met. Moreover, in many cases there is a need to refine the boundaries because of the outcome of the preliminary work (EN ISO 14041:1998(E), EN ISO 14044:2006(E)).

Several life cycle stages, unit processes and flows should be taken into consideration, when defining the initial system boundaries, e.g.:

• Inputs and outputs in the main manufacturing/processing sequence;

• Distribution/transportation;

• Production and use of fuels, electricity and heat;

• Use and maintenance of products;

• Disposal of process waste and products;

• Recovery of used products (including reuse, recycling and energy recovery);

• Manufacture of ancillary materials;

• Manufacture, maintenance and decommissioning of a capital equipment;

• Additional operations, such as lighting and heating (EN ISO 14041:1998(E), EN ISO 14044:2006(E)).

As for the criteria concerning the initial inclusion of inputs and outputs, it is often not practical to model every input and output into the product system. It is an iterative process to identify the inputs and outputs which should be traced to the environment, i.e. to identify which unit processes producing the inputs or which unit processes receiving the outputs should be included in the product system under the study (EN ISO 14041:1998(E), EN ISO 14044:2006(E)).

As the ISO 14044 suggest, one should use the following criteria of inclusion of the inputs and outputs:

• Mass: the inclusion in the study of all inputs that cumulatively contribute more than a defined percentage to the mass input of the product system being modelled;

• Energy: the inclusion in the study those inputs that cumulatively contribute more than a defined percentage of the product system’s energy inputs;

• Environmental relevance: including the inputs that contribute more than an additional defined percentage to the estimated quantity of individual data category of the product system.

2.5.2.3 Data categories and data quality requirements

In the LCA studies, various data sources may be used for the assessment. Data may be collected from the production sites associated with the unit processes (within a system boundary), or it may

be obtained or calculated from existing databases or other published sources. Thus, one obtains the mixture of measured, calculated, or estimated data, where reliability and quality has to be assessed (EN ISO 14040:1997(E), EN ISO 14040:2006(E)).

To estimate the quality of the calculation results, several data quality requirements should be specified. These requirements should address at least:

• Time-related coverage: the desired age of data (e.g. within the last five years) and the minimum length of time (e.g. one year) over which data should be collected;

• Geographical coverage: geographical area from which data for the unit processes should be collected to satisfy the goal of the study (e.g. local, regional, national, continental, global);

• Technology coverage: technology mix (e.g. weighted average of the actual process mix, best available technology or worst operating unit) (EN ISO 14040:1997(E), EN ISO 14040:2006(E), EN ISO 14041:1998(E), EN ISO 14044:2006(E)).

ISO standards specify also other parameters (like i.e. precision, completeness, representativeness, consistency and reproducibility) that may be used depending on the goal and scope. If the LCA study is used to support a comparative assertion that is disclosed to the public, above-mentioned data quality requirements shall be addressed.

2.5.2.4 Comparisons between systems and critical review

If the systems are compared in the LCA, the comparison shall be performed using the same functional unit and equivalent methodological considerations, such as performance, system boundaries, data quality, allocation procedures, decision rules on evaluating inputs and outputs and impact assessment. If any difference between the compared systems occurs, it should be identified and reported. For the results, which are disclosed to the public, a critical review process needs to be carried out. Furthermore, impact assessment shall be performed (EN ISO 14041:1998(E), EN ISO 14044:2006(E)).

2.5.3 Inventory analysis