|Aspect||G-01 Goal definition for building and product LCA|
||According to ISO 14040-44 and the ILCD Handbook, the goal definition of a study is a key LCA requirement, as it guides all the detailed aspects of the scope definition, which then determine the LCI and LCIA provisions. Special attention should be paid to this first step of the LCA methodology, which will influence the study results and determine their applicability. Generally speaking, the goal definition should be documented in detail.How can the practitioner set up the goal of the study? Are there special cases where the effort of goal definition can be simplified in regard to product or building LCAs?|
Related study objective
|☒ stand-alone LCA||☒ comparative assertion|
Related study phase
|goal and scope definition||inventory analysis (LCI)||impact assessment (LCIA)||interpretation||reporting|
|new buildings||existing buildings||construction products||screening LCA||simplified LCA||complete LCA|
|Provisions||The goal definition for a building or product LCA study should be defined according to the ILCD Handbook (e.g. by defining the context and the intended use of the assessment).The documentation should also be in line with ISO 14044, EN 15978 and EN 15804.|
||Goal definition is a crucial aspect of each LCA study. The practitioner should note that this step has implications for all the following general aspects: scope of the study, life cycle inventory analysis, impact assessment, interpretation, reporting and critical review, as well as all the life cycle stage aspects of products and buildings (i.e. aspects for Modules A, B, C and D according to EN 15804/EN 15978). As a result, it is directly connected to all the provisions/guidance provided in the EeBGuide.Guidance for specific aspects of the goal definition are given in the other EeBGuide aspects ‘Comparative assertions,’, ‘Classifying the decision context as situation A, B and C for building and product LCA’ and ‘Future technical development and innovation’.The goal of the study needs to be defined at the beginning of the study and should – with regard to the relations mentioned below – clearly state the objective of the study. Typically, a study cannot adequately address several different goals, but should address one single goal. If several goals are pursued when conducting LCA studies, e.g. within one research project, separate studies – possibly based on a common basic product model – should be conducted.
1) General guidance: need for flexibility versus strictness
2) Practical guidance for building LCA studies
The goal definition needs to clarify the core objective of a building LCA. This goal may be predefined, e.g. by a building certification system, to provide the building LCA for certification purposes. In general, the practitioner needs to define the study’s goal individually.
This definition of the goal serves as the basis for the identification of the study’s scope, which in turn yields the coverage of different contributors to include in the LCA study, such as the building products (Modules A, B, C, D), construction site (Module A5), energy consumption (Module B6), water consumption (Module B7), transport of people (during the use phase of the building) etc.
For building LCA, the EN 15978 guidance should be used by LCA practitioners to define the goal and scope of their study according to the purpose of the assessment. Three applications are identified in EN 15978:
3) Predefined goal for product and building LCA studies according to EeBGuide study types
The definition of the goal of a study within the context of this guidance document is also broadly predefined through the use of the three study types (screening, simplified and complete LCA). The reporting templates of the EeBGuide also help regarding documentation of the goal of an LCA study.
However, the study type (e.g. screening LCA) may be adjusted, depending on the practitioner. This is the reason why the provisions and guidance for the corresponding aspects remain flexible. For example, for the choice of LCA data for a screening LCA, the EeBGuide recommends using different types of data. Architects may prefer to use building components (e.g. 1 m2 of wall, with the possibility of changing the width of structural and insulation products), whereas a construction company may prefer quantifying the impacts of a building design at the level of materials (e.g. kg of steel, or m3 of concrete).
4) Practical guidance for product LCA studies within E2B EI research projects
Within E2B EI research projects, it may be interesting to extend the goal of the project, if relevant. For example, for a product LCA, the primary goal may be to develop a product system model as well as delivering a full LCA study for a specific purpose, such as identifying the environmental impacts of a building design or of a novel product.
In some cases, however, the goal might be required to be extended to secondary applications, e.g. developing an EPD for the corresponding product, or providing the LCA study for building certification purposes. In this case, the same life cycle model can be used if it is suitable according to the relevant PCR (e.g. EN 15804), or to the set of LCA calculation rules of the relevant building certification scheme. The main advantages of extending the goal from the beginning of the study is to reduce the additional effort in e.g. data collection, methodological choices (e.g. use of parameters), reshaping of the product model etc.
However, this type of extension of the goal might be difficult to achieve for innovative products where no detailed PCR exist. In such cases the study should at least comply with the major requirements of the core European PCR (e.g. EN 15804) if the secondary goal is to provide an EPD. In addition, the definition of several goals for a study may make it difficult for the practitioner to meet all the study’s objectives. A trade-off needs to be found between reduced effort through integration of secondary goals and increased effort due to e.g. increased flexibility required of the product model, or multiple results.