|Aspect||G-27 (Buildings) / G-25 (Products) Choice of environmental indicators – screening and simplified LCA|
||The choice of a set of environmental indicators should always try to avoid pollution transfer. Currently, a large number of indicators can be found in the LCA literature. They fall into different: selected LCI indicators, midpoint life cycle impact assessment (LCIA) indicators, and endpoint LCIA indicators. Selected LCI flows can be useful in track some flow quantities: e.g. the use of secondary energy throughout the product’s life cycle. These are not impact indicators directly, but they can be useful in the interpretation phase of any LCA study. Mid-point LCIA indicators (or potential indicators) make it possible to characterize different environmental problems, such as climate change, ozone depletion, photochemical ozone formation, acidification, eutrophication and resource depletion. End-point LCIA indicators refer to actual damage categories such as damage to resources, damage to human health, and damage to the ecosystem.What are the useful and necessary environmental indicators and impact categories to be reported for an energy-efficient product or building? Which indicators and which methodology should be chosen?|
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||building products||screening LCA||simplified LCA||complete LCA|
|Provisions||In general, the set of indicators should be as comprehensive as possible, to avoid burden shifting. The EeBGuide does not provide predefined provisions regarding the number and the type of indicators for each study type, as they depend on the goal, the scope and the context of the study.Required environmental indicators to use are given in the EN 15978 and EN 15804 standards (which are harmonized indicators between the product and the building level), and also in the ILCD Handbook if other indicators need to be included.For screening and simplified LCA studies the choice of indicators is not regulated or limited. Generally speaking, in screening and simplified LCA a reduced set of indicators may be selected, which means that not all the EN 15804 and EN 15978 indicators have to be considered. In addition, optional indicators taken from the ILCD Handbook may be used to provide a more consistent set of indicators (if relevant).|
11 Calculation of the environmental indicators
“[…] VI) MAY – LCIA methodologies: […] select complete set of single LCIA methods rather than selecting and combining individual LCIA methods”
Provisions: 188.8.131.52 Reminder flows
I) MAY – Use reminder flows to keep original information for specific purposes
II) SHALL – exclude reminder flows from impact assessment
III) SHALL – Clearly identify reminder flows in the flow name
8 Life Cycle Impact Assessment – calculating LCIA results
Provisions: 8.2 Calculation of LCIA results
ILCD Handbook – Part – Analysing of existing Environmental Impact Assessment methodologies for use in Life Cycle Assessment
4 Requirements for specific impact categories
“For some impact categories, many alternative methods have been selected. This can be seen as a sign that there is no clear consensus on how to model such a method. Clear examples are acidification, eutrophication, land use and resources.”
||The operational guidance for the environmental indicators can be broken down into two main aspects: the calculation rules for environmental indicators (in both CEN TC 350 standards and in the ILCD Handbook) and the number of indicators to select, depending on the study type.
1) Calculation rules (i.e. characterization factors and associated impact assessment method) for each LCIA indicator in EN 15804/EN 15978
A new method is now suggested for POCP calculations based on [Van Zelm 2008]. Other LCIA methods have been used so far for POCP calculations: for example the CML 2002 approach based on [Derwent 1998]. As a result, care has to be taken, and the method used for LCIA indicators should be clearly stated. In LCA studies across Europe, CML methods are frequently used for midpoint indicators. Also, EPD programmes usually provide results at indicator level, as is done by some generic databases. Using such data reduces the choice of impact methods and also yields a number of indicators to choose from.
PS: Please note that the ADP guidance is given in a separate aspect.
Harmonization of the LCIA indicators is expected soon. The aspect will be revised once there are agreed methods between CEN and ILCD.
2) Calculation rules for each indicator describing resource use and additional information (wastes etc.) in EN 15804/EN 15978
According to the ILCD Handbook, these flows are called ‘reminder flows’ (see ILCD rules above). The practitioner and LCA tool developer may be aware that, so far, not all the resource use indicators can be easily determined. In fact, the background databases used in LCA studies do not provide this information in a consistent way (e.g. ‘use of non-renewable primary energy excluding primary energy resources used by a raw material’). Others are potentially more easily available (e.g. ‘use of secondary fuels’). As the practitioner cannot influence the background data, this problem ultimately needs to be solved by the data providers.
3) Calculation rules for optional indicators (taken from the ILCD Handbook)
Currently there is no agreement on a single calculation method for impact categories not covered in CEN TC 350 (but available in the ILCD Handbook), such as land use, toxicity or ecotoxicity. The type of LCIA modelling between midpoint indicators and endpoint indicators are is subject to discussion. Therefore the EeBGuide does not provide strict provisions on these aspects. Please consult the corresponding aspects for more detailed guidance on those aspects that are not mandatory in the EeBGuide.
4) Number of indicators to consider, depending on the study type.
To select a relevant set of indicators, the practitioner should also try to have indicators covering the three area of protection: resources, ecosystems and human health. The indicators of EN 15804/EN 15978 correspond to these area of protection, but do not include all the impact categories, as some are still being debated within the LCA community. Additional aspects (see ‘Biodiversity’, ‘Land use’, ‘Toxicity and ecotoxicity’ etc.) provide guidance for the practitioner who would like to use them.
For screening and simplified LCA it may be possible to conduct LCA studies using a single indicator under specific conditions. For example:
– if the decision-maker is not very familiar with the LCA approach, or focuses only on energy or greenhouse gas issues;
– if the full LCI data needed to calculate all the LCIA indicators are not available for some national context.
However, it is strongly recommended that more than one environmental indicator be used, to avoid e.g. shifting of burdens. To that end, a selection of indicators from the EN 15978/EN 15804 standards (and from the ILCD Handbook if relevant) is recommended for screening and simplified LCA.
The indicators considered in the SBA common metrics project may be considered for a screening or simplified LCA (if relevant for the goal and scope of the study): non-renewable primary energy, GWP, water consumption and waste.