A complete LCA study reflects the regular approach to LCA, following ISO 14040/14044. It meets the requirements of ISO 14044, and reflects the basis for comparative assertions and other external communication. It covers the entire building’s or product’s life cycle, and yields a comprehensive view of the environmental performance of the building or product. This type of study serves to identify environmental hotspots, and gives assurance concerning the contribution to environmental impacts from individual life cycle stages, building elements, products, components or services. It is recommended that this type of study be used to provide relevant decision support for the detailed design of a building.
Completeness of assessment
Complete LCAs should ideally consider the whole life cycle – that is, from cradle to grave (Module A1 to C4), as well as Module D (if relevant to the goal and scope of the study) – and should consider a comprehensive set of environmental impact categories taken from both EN 15804/EN 15978 and additional indicators described in the ILCD Handbook (if relevant for the purpose of the study).
When a complete LCA is undertaken, to understand the impact of a building over its full life cycle (cradle to grave), care must be taken to review the relevant scenarios that may be applicable to the use phase. Very different assumptions on service life, energy in use, patterns of use, disposal and recycling may be appropriate, leading to more than one scenario evaluation to reflect different practice and impacts. In addition, hundreds of different products are used in the construction of buildings, and it may be very challenging to obtain quantitative environmental information about their production, transportation, service life, recyclability, etc.
The assessment should accurately represent the quantification of the building and scenarios used. In EN 15804 and EN 15978 the following criteria for exclusion of inputs and outputs are defined:
- “1% of renewable and non-renewable primary energy usage and
- 1% of the total mass input of that unit process.
- The total of neglected input flows per module, e.g. per Module A, B, C or D shall be a maximum of 5% of energy usage and mass.”
In the ILCD Handbook these criteria for exclusion of inputs and outputs are defined more strictly as an iterative approach to get as close to 100% as possible.
For a complete LCA the recommendations of the ILCD Handbook should be followed. The definition of the cut-off rules mentioned in EN 15804 and EN 15978 could possibly generate misleading results in specific cases (e.g. in studies with a focus on toxicity). Therefore the EeBGuide stresses that the cut-off rules have to be defined in accordance with the goal and scope of the study.
Whenever LCI data are available for describing, for example, a raw material (for a product LCA) or LCA or EPD data on a building product (for a building LCA), it should be taken into account in the study. Cut-off rules aim only at easing the process of doing an LCA, for example by neglecting plastic bags for an upstream raw material (for a product LCA), or for neglecting minor components in a building (but ensuring that the simplification does not bias the results). For more information, see the cut-off aspect in the guidance document.
In practice, LCA practitioners may face significant challenges to meet these requirements for buildings, as extensive documentation of the building products used in a construction project is required. To-day, such extensive documentation is not generally state-of-the-art for typical construction projects. Experience shows that the situation may be improved significantly if the project developer/investor, the architect and the construction company cooperate from the early design stages onwards, to establish extensive and automated documentation systems for the construction materials and specific products used.
For a complete LCA, stricter requirements must be considered to ensure an appropriate level of data representativeness. ISO 14044 provides a full list of the rules in the following areas:
- Time-related coverage: the period over which the data should be collected, and how recent this data must be.
- Geographical coverage: the geographical area from which data should be collected in order to meet the requirements of the goal and scope of the study.
- Technology coverage: the LCI data should reflect the technology applicable to the product, component, element or part of the building under study.
- Precision: a measure of the variability of the data values.
- Completeness: the percentage of flow that is measured or estimated.
- Representativeness: a qualitative assessment of the degree to which the dataset reflects the true population of interest (i.e. geographical coverage, time period and technology coverage).
- Reproducibility: a qualitative assessment of the extent to which information about the methodology and data values would allow an independent practitioner to reproduce the results reported in the study.
- Sources of the data.
- Uncertainty of the information (e.g. data, models and assumptions).
LCI data should represent the country in which the material is sold, or in which the process or activity is taking place (wherever it occurs in the life cycle).
LCI data should reflect the technology applicable to the product, component, element or part of the building under study.
Specific descriptions of the products (component, element, or part of the building) should be used. Specific EPDs may be used (e.g. if the chosen indicators are covered by the EN 15804/EN 15978 list of indicators), as well as specific LCA data (e.g. if additional impact categories need to be assessed). For other sources of impacts related to the operational energy, water and the construction site, refer to the provisions given in the guidance document.
A qualitative assessment should be made of whether the study methodology is applied uniformly to the various components of the analysis.
Use the reporting template provided. The minimum requirements for items reported on can be summarized as follows:
- Definition of the goal and scope
- Life cycle stages included, and a clear definition of the system boundary
- Input materials/items included, and any excluded, with justification (cut-off rules)
- Impact categories considered (with justification)
- Assumptions and comment on degree of approximation/uncertainties
- Main assumptions and limitations
- Life cycle impact results, broken down by life cycle stage and module
- Statement on consistency
- Interpretation and conclusions
- Review statement
Communication of LCA report and results
Communication can be internal or external. For external communication purposes, an independent review/verification is needed before publication.
Most complete LCAs will be conducted for producing LCA studies of buildings for the detailed design and assessment stages. If a complete LCA is to be used to provide a comparative assertion intended to be disclosed to the public, then there are further requirements set within ISO 14044, and the LCA will require critical review by a panel of interested parties.
Examples of a complete LCA:
- Comparative LCA study of different buildings or building designs.
- Selection of the most appropriate construction strategy for the refurbishment of a building’s envelope.
- Detailed identification of the environmental hotspots of a product or a building.
2 Methodological approach of the EeBGuide.
- 2.1. Identification of important aspects for product and building LCA studies
- 2.2. Reference documents for the EeBGuide.
- 2.3. Procedure for choosing provisions from both CEN TC 350 standards and the ILCD Handbook
- 2.4. Use of three study types
- 2.5. Use of a baseline scenario.