Question 1

What is LCA (Life Cycle Assessment)?

Accepted Answer

LCA is a method that systematically evaluates the inputs, outputs and potential environmental impacts of a product or service across its life cycle, within a defined goal, functional unit and system boundary. The scope of a study can be defined as cradle-to-gate, cradle-to-grave, or another life-cycle boundary appropriate to its purpose.

Question 2

How is an LCA project plan made and the scope defined?

Accepted Answer

First, the study's purpose, target audience, decision context and intended use are defined. Then the functional unit, reference flow, system boundary, data quality requirements, allocation approach, impact assessment method, assumptions and limitations are determined. The scope can be reassessed as needed under the ISO 14040 and ISO 14044 framework as findings develop during the study.

Question 3

What is ISO 14040 and what does it define in LCA?

Accepted Answer

ISO 14040:2006 defines the principles and general framework of Life Cycle Assessment. It explains the relationship between the core components: goal-and-scope definition, life cycle inventory (LCI), life cycle impact assessment (LCIA), interpretation, reporting and critical review. The version reaffirmed by ISO in 2022 remains current.

Question 4

What is ISO 14044 and what do its implementation rules cover?

Accepted Answer

ISO 14044:2006 defines the requirements and guidance for conducting LCA studies. It details goal and scope, data quality, system boundary, allocation, LCI, LCIA, interpretation, reporting and critical review. The standard must be applied together with its current amendments, and methodological choices consistent with the study's purpose must be clearly justified.

Question 5

What are the basic stages of LCA?

Accepted Answer

Under the ISO 14040 and ISO 14044 framework, LCA consists of four main stages: goal-and-scope definition, life cycle inventory (LCI), life cycle impact assessment (LCIA) and interpretation. These stages operate iteratively rather than linearly; earlier stages may be revisited as data and findings develop.

Question 6

How is the functional unit selected?

Accepted Answer

The functional unit is the reference that quantitatively defines the function provided by the product system under study. It must be measurable, suitable for comparison, and consistent with the study's purpose. For example, a coating system may be defined not simply by kilogram of product but by the coated area providing a specific performance and service life.

Question 7

What is the system boundary? What is the difference between cradle-to-gate and cradle-to-grave?

Accepted Answer

The system boundary determines which processes and life-cycle stages are included in the LCA model. The cradle-to-gate approach covers stages from raw material extraction to the plant or factory gate, while cradle-to-grave also includes use and end-of-life stages. The appropriate boundary is selected according to the study's purpose and intended application.

Question 8

How are cut-off criteria determined?

Accepted Answer

Cut-off criteria are determined taking into account the study's goal, scope and data significance. Indicators such as mass, energy or environmental significance can be used; there is no single universal cut-off percentage. Excluded flows and processes must be reported with justification, ensuring that significant environmental impacts are not left outside the system.

Question 9

What are the data quality requirements?

Accepted Answer

Data quality assessment considers temporal, geographical and technological representativeness, as well as completeness, consistency, precision and uncertainty. DQI, the pedigree matrix or other data-quality methods suited to the study's purpose may be used; these tools are not the sole mandatory ISO method.

Question 10

How are primary and secondary data collected?

Accepted Answer

Primary data is obtained from the production facility, supplier or directly measured operations. Secondary data comes from reliable LCI databases, sector sources and published datasets. The data source, reference year, geographical scope, technology and any adaptations made must be recorded to create an audit trail.

Question 11

What are the most common LCI databases?

Accepted Answer

Ecoinvent, Sphera Managed LCA Content and appropriate national or sectoral LCI databases are commonly used sources. Database selection should jointly consider licence conditions, geographical and technological representativeness, data age, modelling approach and compatibility with the LCA software to be used.

Question 12

Which LCA software should be preferred?

Accepted Answer

SimaPro, Sphera LCA for Experts (formerly GaBi Software) and openLCA are among the commonly used LCA modelling tools. The choice should be based on criteria such as the databases to be used, team experience, reporting purpose, model transparency, audit trail and budget. Software selection alone does not guarantee ISO compliance of the study.

Question 13

How is the LCIA method selected?

Accepted Answer

The LCIA method should be selected not only based on geography but also the study's purpose, target audience, relevant PCR or programme rules, and the required impact categories. ReCiPe, TRACI and the European Commission's Environmental Footprint approach can be used in different application contexts. The characterisation model and version used must be clearly stated in the report.

Question 14

How is allocation performed, and which methods can be used?

Accepted Answer

If a process produces more than one product, the priority, where possible, is to avoid allocation, subdivide the process into sub-processes, or consider approaches such as system expansion. If allocation is necessary, physical relationships or, where appropriate, economic relationships can be used. The chosen method must be justified and tested with sensitivity analysis if it significantly affects the result.

Question 15

How are recycling and end-of-life (EoL) modelled?

Accepted Answer

Recycling and end-of-life modelling should be selected according to the study's purpose, the product system and any applicable PCR or programme rules. Cut-off, substitution or sharing approaches can be used in different contexts. For construction product EPD studies, the module and modelling rules under EN 15804 should be applied.

Question 16

How is biogenic carbon and carbon storage reported in LCA?

Accepted Answer

Biogenic carbon flows must be tracked separately from fossil carbon flows; the source of the carbon, its storage duration within the product system, and end-of-life release or transfer assumptions must be clearly stated. The accounting and reporting approach applied must be consistent with the study's purpose and with the relevant PCR, EPD programme or other applicable methodological rules.

Question 17

What is the difference between Product Carbon Footprint (ISO 14067) and LCA?

Accepted Answer

ISO 14067:2018 focuses on quantifying the product carbon footprint using a life-cycle approach consistent with ISO 14040 and ISO 14044. It only addresses the climate change impact category. A full LCA, depending on the study's purpose, can assess multiple environmental impact categories.

Question 18

What is the relationship between EPD (Environmental Product Declaration) and LCA, and how does verification proceed?

Accepted Answer

An EPD is an environmental product declaration in which LCA-based environmental information is presented according to the requirements of an EPD programme and the relevant product category rules (PCR). The current general framework is defined by ISO 14025:2026, and it relies on the use of ISO 14040 and ISO 14044 for the LCA. For construction products, EN 15804 forms the basis of the relevant core PCR rules; different PCRs may apply to other product groups. Verification conditions are carried out according to the relevant programme rules; for example, in the International EPD System, verification is performed by approved individual verifiers or accredited certification bodies.

Question 19

When is a critical review required?

Accepted Answer

Under ISO 14044, the scope of a critical review is determined by the purpose and use of the study. Special critical review requirements become important for comparative assertions intended to be disclosed to the public. ISO 14071:2024 provides detailed requirements and guidance for LCA critical review processes and reviewer competence.

Question 20

How is uncertainty and sensitivity analysis performed?

Accepted Answer

Key assumptions, data ranges, allocation choices and scenarios are tested for their effect on the result. Sensitivity and scenario analysis are basic tools in most studies; probabilistic methods such as Monte Carlo may also be used if the data structure and decision needs require it. Monte Carlo is not mandatory for every LCA study.

Question 21

What is the difference between attributional and consequential LCA?

Accepted Answer

Attributional LCA focuses on attributing environmental burdens to the product system under study within the existing production and supply structure. Consequential LCA aims to model the consequences that a particular decision or change in demand could produce within the system and the market. The choice of approach must be consistent with the study's decision context and purpose.

Question 22

What are hybrid LCA and IO-LCA?

Accepted Answer

Process-based LCA relies on detailed process data, while economic input-output LCA links inter-sector monetary flows to environmental extensions. Hybrid LCA may combine these two approaches to reduce data gaps in the process model or truncated supply-chain effects. The hybrid method used and the data resolution must be clearly reported.

Question 23

When should regionalised and dynamic LCA be used?

Accepted Answer

Regionalised LCA may be more appropriate for location-sensitive environmental impacts such as water use, land use, acidification or ecotoxicity. Dynamic LCA can be assessed for long-lived systems where changes over time in emissions, energy mix or carbon storage and release significantly affect results.

Question 24

How should an LCA report be written, and what outputs should be provided?

Accepted Answer

The technical report should transparently present the goal and scope, functional unit, system boundary, data sources, assumptions, LCI model, LCIA method, results, limitations and interpretations. Flow diagrams, contribution or hotspot analyses, and scenario and sensitivity results make it easier for decision-makers to understand the findings.

Life Cycle Assessment (LCA) Consultancy

What we provide in LCA consultancy

The four main stages of LCA

Environmental impact categories

Key data required for the study

Core deliverables

Technical and official sources

How we work

Frequently asked questions