Question: In the incineration of different wastes that produces electricity and steam, when a study aims to calculate the inventory for the electricity or steam, which co-functions are relevant and how is the inventory handled under allocation?

The electricity and steam are the relevant co-functions, and the inventory is allocated between these two only, with all other flows including the waste treatment services treated as non-functional product flows.

# Allocation in Waste Incineration for Electricity and Steam Production

## Co-Functions in Waste Incineration

When a waste incineration plant produces both **electricity** and **steam (heat)**, the relevant co-functions are:

- **Electricity generation** (exported to grid)
- **Steam/heat delivery** (exported to district heating or industrial users)
- The **waste treatment function** itself (the primary function)

---

## The Allocation Challenge

Incineration involves **multi-functionality**: one process simultaneously:
1. Treats/disposes of waste (a service)
2. Produces electricity (a product)
3. Produces steam/heat (a product)

---

## How Inventory is Handled Under Allocation

### Approach 1: System Expansion (Substitution) — *preferred per ISO 14044*
Avoid allocation by **crediting** the system with avoided burdens:
- Subtract the inventory of the **marginal electricity** displaced on the grid
- Subtract the inventory of the **marginal heat source** displaced (e.g., gas boiler)

### Approach 2: Allocation by Physical Parameters
When allocation cannot be avoided, partition inputs/outputs by:

| Basis | Application |
|-------|-------------|
| **Energy content** (MJ) | Allocate based on energy value of each output |
| **Exergy** | Accounts for quality differences between electricity and steam |
| **Economic value** | Allocate based on revenue from each output |

### Key Formula (Energy Allocation Example):

$$f_{electricity} = \frac{E_{elec}}{E_{elec} + E_{steam}}$$

The fraction of total inventory assigned to electricity = share of useful energy output as electricity.

---

## Practical Handling

- **Electricity inventory** receives its allocated share of:
  - Fuel/waste inputs
  - Air emissions (CO₂, NOₓ, dioxins, etc.)
  - Auxiliary materials (lime, activated carbon)
  - Residues (bottom ash, fly ash)

- **Steam inventory** receives the complementary share

---

## Important Note on Waste Input

The **waste itself** is typically treated as a **burden-free input** (burdens allocated upstream to the waste-generating process), so allocation focuses on distributing the *operational* burdens and outputs between the energy carriers.

Based on Source 1 (ILCD Handbook, p.73):

When a study aims to calculate the inventory for **electricity or steam**, these two outputs (electricity and steam) become the **relevant co-functions** of the process.

Under allocation, the inventory is **allocated between electricity and steam only**. All other flows — including the waste treatment services — are considered **non-functional product flows only** and are not part of the allocation between the two energy co-products.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.73)*

Based on the ILCD Handbook, when a study aims to calculate the inventory for the electricity or steam produced from waste incineration, **the electricity and steam are the relevant co-functions**. Under allocation, the inventory is allocated between these two outputs only, and all other flows — **including the waste treatment services — are considered non-functional product flows only** and are not part of the allocation.

> *"If the study in contrast aims at calculating the inventory for the electricity or the steam, these two are the relevant co-functions. For the latter example and in case of allocation, the inventory would be allocated between these two only and all other flows including the waste treatment services would be considered non-functional product flows only."*

— European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), **p. 73**


Question: In the data quality rating system where two quality indicators may be only "good" rather than "very good," what happens to a data set if more than two indicators are only "good"?

The data set is downgraded to the next quality class.

In that data quality rating system, if more than two indicators are rated only "good" (rather than "very good"), the entire data set is **downgraded to "fair"** (rather than being rated "good").

In other words, the rule is that a data set can still receive an overall "good" quality rating if **at most two** of its indicators are merely "good" (with the rest being "very good"), but once **more than two** indicators fall to only "good," the overall data quality rating drops to "fair."

If more than two quality indicators are only "good" rather than "very good," the data set is downgraded to the next quality class.

(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.1)

Based on Source 1 (European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.1):

If more than two quality indicators are only "good" rather than "very good," **the data set is downgraded to the next quality class**.


Question: When a final exclusion is made from the study's inventory, what must be done and what consequences may result?

The final exclusion must be justified by referring to the cut-off criteria, and it may limit the applicability of the resulting data set or the conclusions that can be drawn from a comparative study.

## Final Exclusion from LCA Inventory

When a final exclusion is made from a study's inventory (life cycle inventory - LCI), the following must be done and consequences may result:

### What Must Be Done:

1. **Documentation** – The exclusion must be **clearly documented and justified** in the LCA report, explaining why the input/output or process was omitted.

2. **Transparency** – The rationale for exclusion must be stated transparently so that reviewers and readers can understand and evaluate the decision.

3. **Statement of Significance** – It must be noted whether the excluded item is likely to **significantly affect** the overall results (i.e., a sensitivity or significance check should be performed).

4. **Reporting** – The exclusion must be reported in accordance with **ISO 14040/14044** requirements, which mandate that all exclusions be listed along with justifications.

---

### Possible Consequences:

- **Reduced completeness** of the inventory, potentially affecting the accuracy of results
- **Underestimation or overestimation** of environmental impacts
- **Reduced comparability** with other LCA studies
- **Critical review challenges** – exclusions may be questioned by reviewers
- **Loss of credibility** if exclusions appear arbitrary or are inadequately justified
- The study's conclusions may be **challenged or invalidated** if significant flows were excluded without sufficient justification

---

In summary, exclusions must be **justified, documented, and reported**, and they risk **compromising the reliability and validity** of the study's results.

Based on the context provided, when a final exclusion is made from the study's inventory:

**What must be done:**
The exclusion must be **justified referring to the cut-off criteria**. An initial list of exclusions should be prepared and iteratively updated to reflect the situation at the end of the study.

**Consequences that may result:**
The exclusion **may limit the applicability of the resulting data set or the conclusions that can be drawn from a comparative study**.

*(Hauschild et al., LCA: Theory and Practice — 37 LCA Cookbook, p.983)*

Additionally, exclusions should be **stated and justified along with a consideration of the significance of any exclusions on the outcome of the study**.

*(Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards (2002), p.482)*

Based on the retrieved sources, when a final exclusion is made from a study's inventory, the following must be done and the following consequences may result:

**What must be done:**

Any final exclusion **must be justified by referring to the cut-off criteria** (Hauschild et al., *LCA Cookbook*, p.983). Additionally, exclusions must be **stated and justified along with a consideration of the significance** of any exclusions on the outcome of the study (Guinée et al., p.482).

**Consequences that may result:**

1. **Limitations on the applicability of the resulting data set** — the exclusion "may limit the applicability of the resulting data set or the conclusions that can be drawn from a comparative study" (Hauschild et al., *LCA Cookbook*, p.983).

2. **Missing quantitative information** must be explicitly flagged — if a flow cannot be quantified, it must be marked as "missing important" to avoid misleading readers, since the true value is not zero, and "the omission must be explicitly addressed and considered in the interpretation of the results" (Hauschild et al., *LCA Cookbook*, p.1026).

3. **Impact on study outcomes** — the significance of the exclusion on the study outcome must be considered, as exclusions can affect what conclusions are drawn (Guinée et al., p.482).


Question: If a product made from 1 kg of material is recycled indefinitely at a recycling rate of 95%, what is the total amount of use obtained, and what formula gives this result?

The total amount of use is 20 kg, obtained using the formula U = p/(1-r), where p = 1 kg and r = 0.95.

## Infinite Recycling with 95% Recovery Rate

### Setup

Each cycle recovers 95% of the material from the previous cycle:

- Cycle 1: 1 kg
- Cycle 2: 0.95 kg
- Cycle 3: 0.95² kg
- Cycle n: 0.95^(n-1) kg

### Formula

This is an **infinite geometric series**:

$$S = \sum_{n=0}^{\infty} r^n = \frac{1}{1-r}$$

Where **r = 0.95** (recycling rate)

### Result

$$S = \frac{1}{1 - 0.95} = \frac{1}{0.05} = \boxed{20 \text{ kg of total material use}}$$

### Interpretation

Starting from **1 kg of virgin material**, indefinite recycling at 95% efficiency yields the **equivalent of 20 kg of total material utility** — meaning the original material is effectively used **20 times** before it is entirely lost to the 5% losses at each cycle.

This principle underpins recycled content and end-of-life recycling credits in **LCA methodology** (e.g., the circular footprint formula in PEF/ISO 14044 contexts).

The total amount of use obtained is **20 kg**.

This result comes from the formula for an indefinite number of recycling loops:

**U = p / (1 - r)**

Where:
- U = total amount of use
- p = primary amount (1 kg)
- r = recycling rate (0.95)

So: U = 1 / (1 - 0.95) = 1 / 0.05 = **20 kg**

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.1 — Annex C)*

Based on the ILCD Handbook, if you start with **p = 1 kg** of material and a **recycling rate of r = 0.95 (95%)**, recycled over an indefinite number of loops, the **total amount of use U = 20 kg**.

This result comes from the simplified formula for an infinite number of recycling loops:

> **U = p / (1 − r)**

So: U = 1 / (1 − 0.95) = 1 / 0.05 = **20 kg**

This is given as **Formula 8** in the ILCD Handbook, which states:

> "In the above example of starting with p = 1 kg and a recycling rate of 95 % (r = 0.95) after indefinite number n of loops one obtains a total amount of use of 20 kg (as in that case U = p/(1-r))."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 1, Annex C)*


Question: What are the three levels of reporting that should be distinguished in an LCA study?

Reports or data sets for internal use; reports or data sets for external use (made available to a limited, well-defined list of recipients including at least one organisation that did not participate in the study); and comparative assertion reports intended to be made available to the (non-technical) public.

In LCA, three levels of reporting are typically distinguished:

1. **Internal report** – A complete, detailed technical report intended for the commissioner/client, containing all data, assumptions, and methodological choices (full transparency for internal use).

2. **Critical review report** – Documentation prepared for or by the critical reviewer, ensuring the study meets ISO standards and scientific/technical validity.

3. **Public report** – A condensed, accessible report intended for external audiences or publication, which must still meet minimum transparency requirements but may omit confidential or proprietary information.

These distinctions are outlined in the **ISO 14040/14044** standards for LCA reporting requirements.

Based on the ILCD Handbook as presented in the report template chapter, the three levels of reporting that should be distinguished in an LCA study are:

1. **Internal use** by the commissioner of the study
2. **Third party** — a limited, well-defined list of recipients with at least one organisation that has not participated in the study
3. **Comparative studies** to be disclosed to the public

[Source 2: Hauschild et al., LCA: Theory and Practice — 38 Report Template, p.1051]

Based on the sources provided, the three reporting levels distinguished in an LCA study are:

1. **Internal use** by the commissioner of the study
2. **Third party** — a limited, well-defined list of recipients with at least one organisation that has not participated in the study
3. **Comparative studies** to be disclosed to the public

(Hauschild et al., LCA: Theory and Practice — **Chapter 38, Report Template, p. 1051**)

This is also consistent with the ILCD Handbook (Source 4, p. 150), which notes that the form and level of reporting depends on the type of deliverable, the purpose and intended applications of the study, and the intended target audience.


Question: When unit process, partly terminated system, and LCI results data sets are the deliverables of a study, for what purpose does provision 8.2 on the calculation of LCIA results apply?

It applies only to quantify the achieved completeness and precision, since these need to be evaluated from the system's perspective.

When unit process, partly terminated system, and LCI results data sets are the deliverables of a study, **provision 8.2 on the calculation of LCIA results applies only for quality check purposes** — that is, to verify the correctness and consistency of the data sets — rather than as the primary goal of the study.

Based on Source 1 (ILCD Handbook, p.280), when unit process, partly terminated system, and LCI results data sets are the deliverables of a study, provision 8.2 on the calculation of LCIA results applies only **to quantify the achieved completeness and precision**, as these need to be evaluated from the system's perspective.

(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.280)

Based on Source 1 (ILCD Handbook, p.280), when unit process, partly terminated system, and LCI results data sets are the deliverables of a study, provision 8.2 on the calculation of LCIA results applies **only to quantify the achieved completeness and precision**, as these need to be evaluated from the system's perspective.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.280)*


Question: When correcting for functional differences of a secondary good, to what must the percentage value relate, and what are some examples of appropriate properties and units?

It must relate to the appropriate property and unit of the secondary good, for example mass in kg for recycled materials, lower calorific value in MJ for recovered energy, and pieces in number for reused parts.

## Correction for Functional Differences in Secondary Goods (System Expansion / Substitution)

When correcting for functional differences between a secondary good (e.g., a co-product or recovered material) and the primary good it substitutes, **the percentage correction value must relate to the functional unit or the relevant functional property** of the reference/primary good being substituted — that is, it expresses how much of the primary good's function the secondary good actually delivers.

---

### What the Percentage Must Relate To

The percentage represents the **ratio of the functional performance of the secondary good to that of the primary good it replaces**, expressed as a fraction of the primary good's functional capacity. In other words: *what proportion of the primary product's function does the secondary product fulfil?*

---

### Examples of Appropriate Properties and Units

| Secondary Good | Functional Property | Unit |
|---|---|---|
| Recycled paper / recovered fibre | Fibre length / tensile strength | mm / N·m/g |
| Secondary aluminium | Metal purity / alloy grade | % metal content |
| Recovered heat / steam | Calorific / thermal energy content | MJ, GJ |
| Compost / digestate | Nutrient content (N, P, K) | kg nutrient per tonne |
| Recycled plastic | Mechanical strength, viscosity (MFI) | MPa, g/10 min |
| Secondary aggregate | Load-bearing capacity | MPa |
| Recovered solvent | Purity / concentration | % by mass |

---

### Key Principle

The correction ensures that the system is credited only for the **actual substituted function**, not a full 1:1 substitution if the secondary good is inferior (or superior) in performance to the virgin/primary equivalent.

The percentage value must relate to the appropriate property and unit of the secondary good. Examples of appropriate properties and units include:

- **Mass in kg** for recycled materials
- **Lower calorific value in MJ** for recovered energy
- **Pieces in number** for reused parts

[Source 1: European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.182]

When correcting for functional differences of a secondary good, the percentage value **must relate to the appropriate property and unit of the secondary good**.

Examples of appropriate properties and units include:

- **Mass in kg** for recycled materials
- **Lower calorific value in MJ** for recovered energy
- **Pieces in number** for reused parts

As stated in the ILCD Handbook: "this % needs to relate to the appropriate property and unit of the secondary good, e.g. Mass in kg for recycled materials, Lower calorific value in MJ for recovered energy, Pieces in number for reused parts, etc."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.182, footnote 132)*


Question: In an LCA, which phase generally constitutes the main part of the work in terms of duration and resources used?

## Life Cycle Inventory (LCI) Phase

The **Life Cycle Inventory (LCI)** phase generally constitutes the main part of the work in terms of duration and resources used in an LCA study.

### Why the LCI is the most demanding phase:

- **Data collection** is extensive and time-consuming — it involves gathering primary and secondary data for all processes across the entire life cycle
- **Data quality verification** requires significant effort (checking completeness, consistency, and reliability)
- **System boundary definition and modelling** of all unit processes demands technical expertise
- **Iterative nature** — data gaps often require repeated efforts to find, estimate, or substitute missing data
- It typically accounts for **60–80% of the total time and resources** spent on an LCA

### Compared to other phases:
| Phase | Relative effort |
|-------|----------------|
| Goal & Scope Definition | Low–Medium |
| **Life Cycle Inventory (LCI)** | **Very High** |
| Life Cycle Impact Assessment (LCIA) | Low–Medium (largely automated with software) |
| Interpretation | Medium |

This is why **data availability and quality** is often cited as the primary challenge in conducting LCA studies.

The **Life Cycle Inventory (LCI)** phase generally constitutes the main part of an LCA in terms of duration and resources used.

This is supported by two sources:

- According to the **ILCD Handbook: General Guide for LCA (2010), p.12**: "The main part of an LCA is generally the inventory work, regarding both duration and resources used."

- This is corroborated by **Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards (2002), p.477**: "The Inventory analysis is generally the most time and resource consuming phase of an LCA."

The **Life Cycle Inventory (LCI) phase** generally constitutes the main part of an LCA in terms of duration and resources used.

This is supported by two sources:

- The ILCD Handbook states: *"The main part of an LCA is generally the inventory work, regarding both duration and resources used"* (European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.12).

- The Guinée et al. Handbook similarly confirms: *"The Inventory analysis is generally the most time and resource consuming phase of an LCA"* (Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards (2002), p.477).


Question: In the described data quality framework, which three complementary aspects do not reflect the actual data quality itself but support it?

Documentation (providing information for reproducibility), Review (assurance of quality), and Nomenclature (supporting data consistency through e.g. the same elementary flows and units of measurement).

In typical LCA (Life Cycle Assessment) data quality frameworks — particularly the one described in the **ecoinvent** context or similar frameworks — the three complementary aspects that **support** data quality rather than directly reflecting it are:

1. **Reproducibility** – the degree to which the methodology and data collection process can be reproduced by an independent practitioner.
2. **Documentation/Completeness of documentation** – the extent to which information about the data and its collection is documented.
3. **Validation/Verification** – whether the data has been reviewed or verified by an independent source.

These aspects are considered **supportive** of data quality (they relate to transparency, traceability, and credibility) rather than being direct measures of the data quality itself (which would cover indicators like temporal, geographical, and technological representativeness, precision/uncertainty, and completeness of flows).

Based on Source 1 (European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.323), the three complementary aspects that do not reflect actual data quality itself but support it are:

1. **Documentation** (providing information of data quality and other aspects as basis for reproducibility)
2. **Review** (assurance of quality)
3. **Nomenclature** (to support data consistency in practice by using e.g. the same elementary flows, units of measurement, etc.)

Based on Source 1 (ILCD Handbook, p.323), the three complementary aspects that do not reflect the actual data quality itself but support it are:

1. **Documentation** (i.e. providing information of data quality and other aspects as basis for reproducibility)
2. **Review** (i.e. assurance of quality)
3. **Nomenclature** (i.e. to support data consistency in practice by using e.g. the same elementary flows, units of measurement, etc.)

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.323)*


Question: Why is carrying out an LCI or LCA study described as an iterative process?

Because as more information becomes available during the data collection, impact assessment, and interpretation phases, the initial scope settings typically need to be refined and sometimes revised.

## LCA as an Iterative Process

An LCA/LCI study is described as an iterative process because **the four phases interact with and inform each other**, requiring repeated refinement as the study progresses.

### Key Reasons:

1. **Data collection reveals scope issues** – When collecting inventory data (LCI phase), gaps or unexpected findings may require revisiting and revising the **goal and scope definition** (e.g., adjusting system boundaries, functional unit, or cut-off criteria).

2. **Impact assessment informs data needs** – Results from the LCIA phase may highlight which data points are most significant, prompting more refined data collection in the LCI phase.

3. **Evolving understanding** – As practitioners work through the study, their understanding of the system deepens, often revealing that initial assumptions were too broad, too narrow, or incorrect.

4. **Sensitivity and completeness checks** – Iterative loops allow for sensitivity analyses that may require re-examining earlier phases to ensure results are robust and meaningful.

### Practical Example:
A preliminary LCIA result might show that a particular process dominates the impact, prompting a return to the LCI to collect more detailed/accurate data for that process, which then changes the LCIA results.

### ISO 14040/14044 Recognition:
This iterative nature is explicitly acknowledged in the **ISO 14040 standard**, which notes that the phases are not strictly sequential — information flows back and forth between phases throughout the study.

Carrying out an LCI or LCA study is described as an iterative process because, once the goal is defined and initial scope settings are established, new information continuously becomes available during the life cycle inventory phase (data collection) and the subsequent impact assessment and interpretation stages. This new information typically requires the initial scope settings to be **refined and sometimes revised**.

As stated in the ILCD Handbook:

> "once the goal of the work is defined, the initial scope settings are derived that define the requirements on the subsequent work. However, as during the life cycle inventory phase of data collection and during the subsequent impact assessment and interpretation more information becomes available, the initial scope settings will typically need to be refined and sometimes also revised."
*(European Commission – JRC, ILCD Handbook: General Guide for LCA, 2010, p. 25)*

Additionally, the process involves **regular checks** to ensure that choices made remain consistent with the goal and scope of the study, and it is not simply a linear sequence of defining steps, gathering data, and writing a report — procedural issues arise throughout the entire LCA process.
*(Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards, 2002, p. 28)*

Furthermore, the iterations serve to **reduce uncertainty**, continuing until the remaining uncertainty is sufficiently small to meet the study's goal.
*(Hauschild et al., LCA: Theory and Practice, Chapter 6, p. 64)*

Carrying out an LCI or LCA study is described as an iterative process because, once the goal of the work is defined, initial scope settings are derived that define the requirements on subsequent work. However, as data collection proceeds during the life cycle inventory phase, and as more information becomes available during the subsequent impact assessment and interpretation, the initial scope settings will typically need to be refined and sometimes also revised (ILCD Handbook: General Guide for LCA, p.25).

This iterative nature means that the individual phases of an LCA use results of the other phases, contributing to the comprehensiveness and consistency of the study (Finkbeiner et al., p.83). Furthermore, the uncertainty of LCA results is reduced through repeated iterations, which are carried on until the remaining uncertainty is sufficiently small to meet the goal of the study (Hauschild et al., Chapter 6, p.64).

As Guinée et al. emphasize, LCA requires "ongoing reflection throughout," including regular checks to see whether the choices made are consistent with the goal and scope of the study — meaning it "is not a matter of defining procedural steps, gathering data, making calculations and then writing a report" (Guinée et al., p.28). It is also noted that it may be necessary to revise the initial objectives and intended decisions during the course of an LCA, making it "an iterative rather than purely sequential process" (Guinée et al., p.457).


Question: Why is using the direct market value for allocation considered somewhat distorting for waste and end-of-life products?

Because waste and end-of-life products with a negative market value can still have a "value"—namely when their value is higher (i.e., the waste fee is less negative) than the default option such as discarding the waste without benefit, e.g., landfilling without energy recovery.

## Why Direct Market Value Allocation is Distorting for Waste and End-of-Life Products

Using direct market value for allocation is considered distorting for waste and end-of-life products primarily because **market prices for these materials are highly volatile, context-dependent, and can be zero or even negative**, which creates several problems:

### Key Issues:

1. **Near-zero or negative prices**: Waste materials may have little or no market value (or require payment for disposal), which would result in zero or negligible burden allocation — effectively "hiding" environmental burdens rather than reflecting physical reality.

2. **Price volatility**: Market values for secondary materials (e.g., scrap metals, recovered plastics) fluctuate significantly over time, meaning the allocated burdens would change dramatically depending on *when* the study is conducted, even if the physical process remains unchanged.

3. **Price reflects scarcity/supply conditions, not physical flows**: Market price is driven by supply and demand dynamics rather than the actual material or energy content involved in the process, making it a poor proxy for physical causality.

4. **Inconsistency**: The same material could have very different values in different markets or regions, leading to inconsistent results across studies.

### Consequence:
The allocation outcome becomes **arbitrary and unstable**, undermining the reproducibility and comparability of LCA results — which is why ISO 14044 recommends physical allocation (e.g., mass, energy content) as preferable when causal relationships can be established.

Using the direct market value for allocation is considered somewhat distorting for waste and end-of-life products because **waste and end-of-life products with a negative market value can still have a "value"** — specifically when that value is higher (i.e., the waste fee is less negative) than the default option of discarding the waste or end-of-life product without benefit, such as landfilling without energy recovery.

In other words, the direct market value does not account for the cost difference relative to the default waste disposal option (the "waste fee cost"), which means it fails to capture the relative economic benefit that certain waste streams may provide compared to simply being landfilled.

*(ILCD Handbook: General Guide for LCA, European Commission – JRC, 2010, p. 266)*

According to the ILCD Handbook, using the direct market value for allocation is considered somewhat distorting because **waste and end-of-life products with a negative market value can still have a "value"**: specifically, when that value is higher (i.e., the waste fee is less negative) than the default option of discarding the waste or end-of-life product without benefit, such as landfilling without energy recovery.

In other words, the direct market value approach fails to capture the relative benefit of choosing one waste management option over another (e.g., recycling vs. landfilling), since it uses zero as the reference point rather than the cost difference compared to the default waste fee cost. The ILCD Handbook notes that a "waste fee adjusted market value" approach — which considers the cost difference to the waste fee cost instead of the direct market value of zero — would be a more accurate allocation criterion, but still needs to be developed and practice tested.

*(ILCD Handbook: General Guide for LCA, p. 266)*


Question: In which phase of an LCA does the identification of the specific processes take place, after the question of which activities relate to a product or process is answered?

The identification of specific processes takes place in the **inventory analysis phase** (Life Cycle Inventory, LCI) of an LCA.

After the goal and scope definition phase establishes which activities are relevant (i.e., defines the system boundary), the inventory analysis phase involves the detailed identification and mapping of the specific unit processes within the system, followed by data collection and quantification of inputs and outputs for each of those processes.

The identification of specific processes takes place in the **Life Cycle Inventory (LCI) phase**.

As stated in the ILCD Handbook: "Identify processes within system boundary: As first step of the LCI phase and depending on the applicable Goal Situation, identify the to-be-included processes within your system boundaries."

[Source 2: European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.12]

Based on the context, the identification of specific processes takes place in the **Life Cycle Inventory (LCI) phase**.

As stated in the ILCD Handbook: "**Identify processes within system boundary**: As first step of the LCI phase and depending on the applicable Goal Situation, identify the to-be-included processes within your system boundaries. Note that the step relates to the processes of the foreground system only, and to the product and waste flows that connect foreground and background system."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.12)*


Question: In Situation C1, how is the multifunctionality of processes and systems solved, and how does this differ from Situation A?

It is solved with substitution via system expansion, as in Situation A, but independently of the absolute amount of the not (function).

I need to clarify that "Situation C1" and "Situation A" appear to refer to specific classifications within the **ISO 14044** standard (and related guidance documents like the ILCD Handbook) for handling **multifunctionality** in Life Cycle Assessment (LCA).

---

## Situation A
In **Situation A**, there is **no multifunctionality problem** — the process delivers only one function (or co-products are negligible), so **no allocation or system expansion is needed**. The system boundaries are straightforward, and all inputs/outputs are attributed to the single product/function.

---

## Situation C1
**Situation C1** applies when a process delivers **multiple functions** and the multifunctionality **cannot be avoided** by subdivision or system expansion (as in Situation B). In C1:

- **Allocation based on physical/causal relationships** is applied — typically using **physical properties** (e.g., mass, energy content, volume) that reflect an underlying causal or physical relationship between the co-products and the process.
- The environmental burdens are **partitioned** among co-products according to these physical parameters.
- If no physical causal relationship can be established, **economic allocation** (based on market value) may be used as a fallback.

---

## Key Difference

| Aspect | Situation A | Situation C1 |
|---|---|---|
| Multifunctionality | Absent | Present and unavoidable |
| Solution approach | No allocation needed | Allocation (physical or economic) |
| Complexity | Simple, single-function | Requires partitioning of burdens |

In essence, **Situation A requires no intervention**, while **Situation C1 requires a deliberate allocation procedure** to distribute environmental burdens among co-functions/products.

Based on the context provided, in **Situation C1**, multifunctionality of processes and systems is solved **with substitution via system expansion**, the same method used in Situation A — but with a key difference:

In **Situation A**, system expansion via substitution is applied based on the **absolute amount of consequences** (i.e., whether large-scale or small-scale consequences are triggered by the analysed decision).

In **Situation C1**, however, substitution via system expansion is applied **independently of the absolute amount** of the not-[large-scale] consequences. In other words, the scale of consequences does not determine the approach — system expansion is applied regardless.

Additionally, Situation C1 is described as **"Accounting, with system-external interactions"** — it includes **existing interactions** with other systems (e.g., recycling benefits or avoided production for co-products), whereas Situation A models **additional consequences** that are assumed to be *caused* by the analysed decision. This is a conceptual distinction: Situation C1 reflects existing interactions, not decision-triggered consequences.

> *Sources: ILCD Handbook, p. 92 (Situation C provisions and differences from Situation A) and p. 43 (definition and distinction of Situation C1 vs. Situation A).*

Based on the sources, in **Situation C1**, multifunctionality of processes and systems is solved through **substitution via system expansion**, the same method used in Situation A — but with a key difference.

As stated in the ILCD Handbook:

> "Situation C1: Multifunctionality of processes and systems shall be solved with substitution via system expansion, as in Situation A, but independently of the absolute amount of the not [large-scale consequences]." *(ILCD Handbook, p.92)*

The distinction is that in **Situation A**, system expansion via substitution is applied with consideration of whether the consequences triggered are large-scale or small-scale (i.e., the scale of the additional demand or supply relative to installed capacity matters for determining which processes are substituted). In **Situation C1**, however, this substitution is applied **independently of the absolute amount** of consequences on other systems — because Situation C1 is purely descriptive/accounting in nature, dealing only with **existing interactions** with other systems (e.g., recycling benefits or avoided production for co-products), rather than modeling additional consequences caused by a decision.

Furthermore, Situation C1 is defined as accounting "with system-external interactions," meaning existing interactions with other systems are included in the LCI model, in contrast to **Situation C2**, where the system is accounted for in isolation and multifunctionality is solved internally by allocation. *(ILCD Handbook, p.43)*


Question: In ILCD multifunctionality allocation, what procedure is applied directly when the market price of the waste or end-of-life product is equal to or above zero?

The two-step allocation procedure is applied directly between the process step that generates the waste or end-of-life product and the true joint process.

In ILCD multifunctionality allocation, when the market price of the waste or end-of-life product is **equal to or above zero**, it is treated as a **co-product** (i.e., it has economic value), and **economic allocation** (allocation by market price/economic value) is applied directly among the co-products.

In other words, a non-negative market price indicates the material is not a true "waste" but a marketable by-product, so the standard **allocation by economic value** procedure is applied directly without any need for system expansion or waste-specific adjustments.

When the market price of the waste or end-of-life product is **equal to or above zero**, the **two-step allocation procedure** is applied **directly** between the process step that generates the waste or end-of-life product and the true joint process.

*(Source 1, p.271 — Provision VI.b.ii)*

When the market price of the waste or end-of-life product is equal to or above zero, the **two-step allocation procedure** is applied directly between the process step that generates the waste or end-of-life product and the true joint process.

As stated in the ILCD Handbook (p. 271):

> "VI.b.ii) Market value equal or above zero: If the market price of the waste / end-of-life product is equal or above zero, the two-step allocation procedure shall directly be applied between the process step that generates the waste or end-of-life product and the true joint process."

This is further elaborated in **Annex 14.4.1.2** (p. 2 of that annex), which specifies that when the market value of the waste/end-of-life product at its point of origin is above zero, it is treated as a co-product in LCA terms, and multifunctionality is resolved by applying the two-step procedure detailed in **chapter 7.9.3**.


Question: Which institute is Stefan Diederichs affiliated with, as listed in the passage?

The Johann Heinrich von Thünen-Institut, Federal Research Institute for Rural Areas, Forestry and Fisheries, Institute for Wood Technology and Wood Biology.

I don't have a specific passage in front of me to reference. Could you please provide the passage you're referring to? That way, I can accurately identify which institute Stefan Diederichs is affiliated with as listed in that text.

Stefan Diederichs is affiliated with the **Johann Heinrich von Thünen-Institut, Federal Research Institute for Rural Areas, Forestry and Fisheries, Institute for Wood Technology and Wood Biology**.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.388)*


Question: Why are the substances emitted by an analysed system into a context system described as formally not being emissions, even though they are called emissions for simplicity?

Because they are emitted inside the technosphere (the context system) rather than into the environment, making them formally equivalent to untreated emissions such as raw gas or raw wastewater rather than true emissions; they are still called emissions when viewed from the perspective of the analysed system.

In LCA, substances transferred from the analysed system to a **context system** (technosphere or ecosphere) are formally described as **outputs** (or exchanges) rather than true "emissions" in the strict sense, because:

**The formal reason** is that "emission" in the thermodynamic/physical sense implies a one-way, irreversible release into the environment. However, within the LCA framework's formal structure:

- The **context system** (background technosphere or ecosphere) is treated as a **separate system** that *receives* outputs from the foreground/analysed system.
- These transfers are formally **flows between systems** — they are outputs of the analysed system that become inputs to (or burdens on) the context system.
- They are not "emissions" in the strict formal sense because **the context system can, in principle, process or respond to them** (e.g., the ecosphere absorbs, transforms, or is affected by them), meaning they are modeled as interactions rather than simple unidirectional releases.

More precisely, in Heijungs & Suh's (and similar) mathematical frameworks, **emissions are a subset of environmental interventions** — they are outputs crossing the **system boundary into the ecosphere**. Until that boundary is crossed, they are formally just **flows**. Calling them "emissions" is a simplification of convenience used in LCA practice (e.g., in inventory tables), but formally they represent **exchange flows** between a technosphere process and its context.

In short: they are called emissions loosely for practical communication, but formally they are **outputs/exchanges** because the LCA mathematical structure treats them as flows crossing system boundaries rather than as categorically distinct "emission" events.

Because these substances are emitted **inside the technosphere** (i.e., within the context system), they are formally not emissions in the environmental sense, but are instead equivalent to untreated releases such as raw gas or raw wastewater. True emissions, in the LCA sense, refer to releases into the natural environment, whereas these substances remain within the technosphere. However, they are still called "emissions" for simplicity, when viewed from the perspective of the analysed system.

**Source: European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 156**

Because these substances are emitted **inside the technosphere** — that is, within the context system itself — rather than being released directly into the natural environment. As such, they are formally equivalent to untreated emissions such as raw gas or raw wastewater, not true emissions in the LCA sense. However, for simplicity, they are still called "emissions" when viewed from the perspective of the analysed system.

As stated in the ILCD Handbook:

> "As these 'emissions' are emitted inside the technosphere, i.e. the context system, they are formally no emissions but equivalent to untreated emissions such as raw gas or raw wastewater. For simplicity they are nevertheless called emissions here, looking at them from the perspective of the analysed system."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 156)*


Question: Why should normalised LCIA results not be summed directly, and what does doing so implicitly assume?

Because directly summing normalised LCIA results is equivalent to choosing an equal weight for all impact categories, meaning a weighting is always at least implicitly involved; if summing or comparison is intended, it should include an explicit weighting step (with equal weights).

## Why Normalised LCIA Results Should Not Be Summed Directly

### What Normalisation Does

Normalisation expresses each impact category score as a fraction of a **reference value** (e.g., the annual impact of a region or average person):

$$N_k = \frac{S_k}{R_k}$$

where $S_k$ is the characterised score and $R_k$ is the reference total for category $k$.

---

### The Core Problem

Summing normalised scores across categories:

$$\sum_k N_k$$

is **mathematically and ethically illegitimate** without explicit weighting, for several reasons:

| Issue | Explanation |
|-------|-------------|
| **Implicit equal weighting** | Summation treats every impact category as equally important — a hidden value judgement presented as if it were neutral |
| **Dimensional inconsistency** | Each $N_k$ is dimensionless but represents fundamentally different environmental concerns (climate, toxicity, biodiversity, etc.) that are **not commensurable** |
| **Reference system dependency** | The magnitude of $N_k$ depends entirely on the chosen reference system; a different reference makes the sum meaningless in a different way |
| **Masking trade-offs** | Large scores in one category can cancel small scores in another, hiding genuine environmental burdens |
| **No scientific basis for equivalence** | There is no physical or ecological law that equates one unit of normalised climate change with one unit of normalised eutrophication |

---

### What Direct Summation Implicitly Assumes

1. **Equal social/political weight** for all impact categories
2. **Equal severity per unit of normalised score** across categories
3. **Perfect substitutability** — harm in one area can offset harm in another
4. That the **reference system is a meaningful common scale**, which it is not inherently

---

### The Correct Approach

If aggregation is desired, an explicit **weighting step** must follow normalisation, applying deliberate, transparent weighting factors ($w_k$) derived from value choices (e.g., panel weighting, distance-to-target):

$$\text{Weighted score} = \sum_k w_k \cdot N_k$$

ISO 14044 flags weighting (and therefore implicit weighting through summing) as a value-laden step requiring transparency, and prohibits its use in comparative assertions disclosed to the public without clear justification.

Normalised LCIA results should not be summed directly because doing so is **equivalent to assigning equal weight to all impact categories**. This implicit assumption means that a weighting step is always at least implicitly involved when summing normalised results — even if no explicit weighting has been declared.

As stated in the ILCD Handbook:

> "summing them up directly is equivalent to choose an equal weight for all impact categories. Hence, a weighting is always at least implicitly involved when summing up normalised LCIA results. If summing or comparison across the normalised LCIA results is intended, this shall include an explicit weighting step with equal weights."

This also applies at the endpoint level, where, for example, damage to the Natural environment may be judged as more relevant than depletion of Natural resources — further illustrating why equal weighting cannot be assumed without justification.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 282)*

This is corroborated by Hauschild et al., who similarly note:

> "normalised results shall not directly be summed up across different impact categories, as this would imply an even weighting of all impact categories. This is unless this even weighting is intended and identified explicitly as weighting when communicating the results."

*(Hauschild et al., LCA: Theory and Practice, 37 LCA Cookbook, p. 1038)*

Normalised LCIA results should not be summed directly because doing so is **equivalent to choosing an equal weight for all impact categories**. The normalised results reflect only the contribution of the analysed product to the total impact potential, but not the severity or relevance of the respective total impact. Therefore, summing them directly implicitly assumes that all impact categories are of equal importance — i.e., it involves an implicit equal weighting.

As stated in the ILCD Handbook: *"summing them up directly is equivalent to choose an equal weight for all impact categories. Hence, a weighting is always at least implicitly involved when summing up normalised LCIA results. If summing or comparison across the normalised LCIA results is intended, this shall include an explicit weighting step with equal weights."*

This applies equally to normalised LCIA results at the endpoint level, where different areas of protection (e.g., Natural environment vs. Natural resources) may warrant different levels of concern.

**(ILCD Handbook: General Guide for LCA, p. 282; confirmed also in Hauschild et al., LCA Cookbook, p. 1038)**


Question: On which page does the section about optionally extending the goal begin?

I don't have access to a specific document or text you're referring to. Could you please provide more context about which document, standard, report, or publication you're asking about? That way, I can help you locate the section about optionally extending the goal.

Based on Source 1 and Source 2, the section about optionally extending the goal (Section 5.5) begins on **page 50** of the ILCD Handbook: General Guide for LCA (2010).

Based on the sources provided, the section about "Optionally extending the goal" begins on **page 50** of the ILCD Handbook: General Guide for LCA (2010), under provision **5.5 Optionally extending the goal**.


Question: What is the name of Situation A in the LCI modelling provisions?

In LCI (Life Cycle Inventory) modelling provisions, **Situation A** is known as **"Attributional"** modelling (or sometimes referred to as the **"non-substitution"** situation).

However, if you are referring specifically to the ISO 14044 / ILCD terminology, Situation A is called **"Situation A: Accounting for the system as it is"** — more precisely, in the ILCD Handbook context, the situations are defined as:

- **Situation A**: **Micro-level decision support** (attributional/consequential depending on context)

Could you clarify which framework or document you're referring to? In the **ILCD Handbook**, the modelling situations are:

- **Situation A**: *Large-scale policy/market decisions* — associated with **consequential/system expansion** modelling.

To give you the precise name, the **ILCD Handbook** defines **Situation A** as related to **"decisions with large-scale consequences"**, using a **consequential LCA approach**.

Would you like me to clarify further based on a specific standard or document?

**"Micro-level decision support"**

This is the name of Situation A in the LCI modelling provisions, as stated in the ILCD Handbook (p.88, Section 6.5.4.2):

> *"I.a) Situation A - 'Micro-level decision support'"*

It is also confirmed on p.81 (Section 6.5.4.2.1):

> *"Situation A relates to a life cycle based decision support on micro-level (e.g. for product-related questions)."*

Situation A is named **"Micro-level decision support"**.

*(ILCD Handbook: General Guide for LCA (2010), p. 88, Section 6.5.4.2)*


Question: What purpose does identifying the target audience of an LCA study serve?

It helps identify the critical review needs and the appropriate form and technical level of reporting, by specifying to whom the results are intended to be communicated.

Identifying the target audience of an LCA study serves several important purposes:

1. **Shapes the level of detail and complexity** – The depth of analysis, technical language, and methodology can be tailored to whether the audience is technical experts, policymakers, business decision-makers, or the general public.

2. **Guides communication and reporting** – Results, conclusions, and recommendations can be presented in a format and language appropriate for the intended readers, improving clarity and usability.

3. **Informs the scope and boundaries** – Knowing who will use the results helps define what questions need to be answered and which impact categories or life cycle stages are most relevant.

4. **Ensures appropriate transparency and documentation** – Different audiences require different levels of documentation; a peer-reviewed scientific study demands more rigor than an internal business report.

5. **Supports decision relevance** – It ensures the study is structured to directly support the decisions or purposes for which it is commissioned (e.g., product comparison, policy development, eco-design).

6. **Facilitates critical review requirements** – Under ISO 14040/14044, if results are intended for public disclosure or comparative assertions, specific review procedures are required, making audience identification essential for compliance.

In essence, identifying the target audience ensures the LCA study is **fit for purpose** — delivering actionable, credible, and appropriately communicated information to those who will use it.

Identifying the target audience of an LCA study serves several important purposes:

1. **Guides reporting detail and technical level**: The target audience greatly influences the extent to which details of the study should be documented and the technical level of reporting (Hauschild et al., *LCA: Theory and Practice* — Chapter 7 Goal Definition, p.72).

2. **Shapes interpretation of results**: The target audience influences how results are interpreted and communicated (Hauschild et al., p.72).

3. **Informs uncertainty communication strategy**: Identifying the target audience is essential before choosing what uncertainty information should be conveyed, with how much detail, and how exactly, since each audience will understand and interpret uncertainty information differently depending on their familiarity with LCA methodology (Hauschild et al., Chapter 11, p.307).

4. **Ensures appropriate classification**: The ILCD Handbook requires that the target audience be unambiguously identified and classified as "internal," "restricted external," or "public," and as "technical" or "non-technical," to ensure proper communication (European Commission – JRC, ILCD Handbook, p.36).

5. **Reduces risk of misinterpretation**: Especially in public communication, identifying the audience is critical because risks of misinterpretation are heightened when LCA-derived information is provided to audiences unfamiliar with the methodology's complexity (ILCD Handbook, p.307).

Identifying the target audience of an LCA study serves several interconnected purposes:

1. **Determining documentation and reporting requirements**: The target audience "greatly influences the extent to which details of the study should be documented, the technical level of reporting and the interpretation of results" (Hauschild et al., *LCA: Theory and Practice*, Chapter 7 Goal Definition, p.72).

2. **Guiding communication strategy**: It is "essential to identify the target audience(s) of this information and adapt the communication strategy accordingly," as "each potential target audience will understand and interpret uncertainty information differently in function of how familiar they are with underlying methodology, sources, types and meaning of uncertainty" (Hauschild et al., *LCA: Theory and Practice*, p.307).

3. **Meeting mandatory goal definition requirements**: The ILCD Handbook states that a study **SHALL** "unambiguously identify the audience(s) to whom the results of the study are foreseen to be communicated" and classify them as "internal," "restricted external," or "public," and differentiate between "technical" and "non-technical" audiences (ILCD Handbook, p.36).

4. **Mitigating misinterpretation risks**: This is "especially critical" in the public domain, as "risks of misinterpretation are heightened when LCA-derived information is provided to audiences not familiar with the complexity of the methodology" (ILCD Handbook, p.307).


Question: In the matrix approach, what condition must be met for the connection of product and waste flows between processes to be done automatically?

All product and waste flows on the output and input sides of all processes that are to be connected must be identically named.

In the matrix approach, the connection of product and waste flows between processes can be done **automatically** when the flows have **identical names (and units)** — i.e., the output flow of one process must have exactly the same name (and matching unit) as the input flow of another process. When flow names match exactly across processes, the software can automatically link them without manual intervention.

In the matrix approach, the condition that must be met for the connection of product and waste flows between processes to be done automatically is that **all to-be-connected product and waste flows on the output and input side of all processes must be identically named**.

*(Source 1: European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.252)*

In the matrix approach, the connection of product and waste flows between processes is done automatically provided that **all to-be-connected product and waste flows on the output and input side of all processes are identically named**.

(ILCD Handbook: General Guide for LCA, p. 252)


Question: What form of misleading interpretation occurs when conclusions for a specific country or technology are treated as valid for broader cases, and what example illustrates the appropriate scope-limited goal?

It occurs when results are interpreted beyond what the chosen scope definition supports—generalising conclusions for specific cases (e.g., a specific technology, use scenario, or country) to broader cases (a family of technologies, all uses, or globally). The example is a comparative diaper study whose goal is defined as the comparison of reusable and single-use diapers in Country X.

## Misleading Interpretation: Overgeneralization (or "Scope Fallacy")

The form of misleading interpretation you're describing is **overgeneralization** — specifically, taking conclusions derived from a **specific, scope-limited LCA study** and incorrectly applying them as universal truths across broader geographic regions, technology portfolios, or contexts.

In LCA methodology, this is closely related to violating the **"goal and scope" boundary** — a foundational principle requiring that conclusions remain within the defined system boundary.

---

## Example of Appropriate Scope-Limited Goal

A well-defined, scope-appropriate goal statement would be:

> **"To compare the greenhouse gas emissions of electric vehicles versus gasoline vehicles *in the Norwegian electricity grid context*"**

- **Appropriate conclusion**: "EVs have lower lifecycle emissions *in Norway* due to the dominance of hydropower."
- **Misleading overgeneralization**: Treating this conclusion as valid for countries with coal-heavy grids (e.g., Poland or India), where the result could be reversed.

---

## Key Principle

The **ISO 14040/14044 standards** explicitly require that:
- The **intended application** and **audience** define the scope
- Comparisons are only valid when systems share the **same functional unit** and **system boundary**
- Results must **not be extrapolated** beyond the defined geographic, temporal, or technological scope

This keeps conclusions **honest, defensible, and contextually accurate**.

When conclusions for specific cases (e.g., a specific technology, specific use scenario, or specific country) are generalised to be valid for broader cases (such as a family of technologies, all uses, or globally), this constitutes **interpreting the results beyond what is supported with the chosen scope definition**.

The example provided to illustrate an appropriately scope-limited goal is from a comparative study of diapers, where the goal is explicitly defined as **"Comparison of reusable and single-use diapers in Country X"** — thereby restricting the validity of the conclusions to that specific country context rather than allowing generalisation to other countries or broader populations.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 371)*

When conclusions for specific cases (e.g., a specific technology, specific use scenario, or specific country) are generalised to be valid for broader cases (a family of technologies, all uses, or globally), this constitutes a form of **misleading interpretation** described as "interpreting the results beyond what is supported with the chosen scope definition."

The example provided to illustrate an appropriately scope-limited goal is a **comparative study of diapers** where the goal is explicitly defined as *"Comparison of reusable and single-use diapers in Country X"* — meaning the conclusions are valid only for that specific country context and should not be generalised beyond it.

*(ILCD Handbook: General Guide for LCA (2010), p. 371)*


Question: When claiming compliance with the ILCD Handbook, what must be identified in connection to the claim?

The applied version or edition of the ILCD "General guide for LCA" must be identified in connection to the claim.

When claiming compliance with the ILCD Handbook, the **specific entry point(s)** (i.e., the specific ILCD conformity level or levels) must be identified in connection with the claim. Specifically, the claim must identify:

- The **specific ILCD conformity level** being claimed (e.g., Level 1 – "Entry level I" or Level 2 – "Entry level II")
- The **specific sections or requirements** of the ILCD Handbook to which the compliance claim applies

In practice, any compliance claim must clearly state **which part/level of the ILCD Handbook** the study or data set conforms to, since the Handbook covers different types of studies and data with different requirements, and blanket claims of "ILCD compliance" without specifying the entry point or level would be insufficient and potentially misleading.

When claiming compliance with the ILCD Handbook, the following must be identified:

1. **The performed review type and reviewer(s)**, if any, shall be identified in the data set.
2. **The applied version or edition** of the ILCD "General [Guide]" must be identified when claiming compliance.

*(Source 2, p.18)*

Additionally, if a **new version** of any applicable ILCD component has been published but an older version is used, **the name of the component and the publication date of the new version** shall be clearly identified in the study or other deliverable that claims compliance.

*(Source 6, p.16)*

Based on the retrieved passages, when claiming compliance with the ILCD Handbook, the following must be identified:

1. **The performed review type and reviewer(s)**, if any, shall be identified in the data set (p.18).

2. **The applied version or edition** of the ILCD "General Guide" shall be identified when claiming compliance (p.18).

3. **If a newer version exists but an older version is used**, the name of the component and the publication date of the new version shall be clearly identified in the study or other deliverable that claims compliance (p.16).

Additionally, compliance is structured around **five groups of aspects: Data quality, Method, Nomenclature, Review, and Documentation**, which shall also be used when referring to selected ILCD compliance criteria and reporting partial compliance in a structured way (p.334).

*(Sources: ILCD Handbook, pp. 16, 18, 334)*


Question: In the window LCA example, which component is set as level 0 after the analysed window system's levels 1 to 3 processes have been identified?

Window glass becomes the new level 0 process.

In the window LCA example, the **background system** (specifically the energy and material production processes, i.e., the upstream/background processes) is set as **level 0**.

More precisely, in the typical window LCA system boundary illustration, **Level 0** represents the **background system** — the upstream processes (such as raw material extraction and energy generation) that supply inputs to the foreground system. After the analysed window system's own processes are identified at levels 1 to 3 (e.g., manufacturing, use, end-of-life), Level 0 is set as the background/upstream supply processes that feed into those levels.

**Window glass** is set as the new level 0 process after the analysed window system's levels 1 to 3 processes have been identified.

As stated in the ILCD Handbook: "After having identified the processes at the levels 1 to 3, each of them becomes a new level 0 process (here shown: 'window glass' as oval in the middle)."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.161)*

Based on the ILCD Handbook, after the levels 1 to 3 processes have been identified for the initially analysed window system, each of those identified processes becomes a new level 0 process. The specific example given is **"window glass"**, which is shown as the new level 0 process (depicted as an oval in the middle of Figure 20).

> "After having identified the processes at the levels 1 to 3, each of them becomes a new level 0 process (here shown: 'window glass' as oval in the middle)."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.161)*


Question: In life-cycle assessment, what are the two functions that a product to be recycled is considered to have?

Firstly, the function(s) the product is primarily made for, and secondly, the function of providing secondary resources for use in subsequent life cycles or systems.

In LCA, a product to be recycled is considered to have two functions:

1. **Its primary function** – the service it provides during its use phase (e.g., being a beverage container, a structural material, etc.)
2. **The supply of secondary material (recyclate)** after end of life – i.e., it provides recovered/recycled material that can substitute for virgin material in future production.

This dual-function nature is at the heart of the **system expansion / substitution approach** (or the recycled content / end-of-life recycling allocation debate), where credit may be given for the avoided production of virgin material that the recycled output displaces.

Based on Source 1 (European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.343), a product to be recycled is considered to have two functions:

1. **The function(s) the product is primarily made for**
2. **The function of providing secondary resources for use in subsequent life cycles / systems**

As stated in the text: "Recycling is methodologically a case of multifunctionality, with the product to be recycled having two functions: firstly the function(s) the product is primarily made for and secondly the function of providing secondary resources for use in subsequent life cycles / systems."

According to the ILCD Handbook, a product to be recycled has two functions: **firstly, the function(s) the product is primarily made for, and secondly, the function of providing secondary resources for use in subsequent life cycles / systems.**

This is why recycling is methodologically considered a case of multifunctionality in LCA.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.343)*


Question: In life-cycle-assessment, what characterizes Situation B as a context for life cycle based decision support?

Situation B refers to life cycle based decision support whose consequences are so extensive that they overcome thresholds and result in additionally installed or decommissioned equipment/capacity (e.g. production infrastructure) outside the foreground system of the analysed system.

## Situation B in LCA Decision Support

In the context of life cycle-based decision support (as described in the consequential vs. attributional LCA framework, particularly as outlined by researchers like Ekvall and Weidema), **Situation B** is characterized by:

### Key Characteristics:

- **Large-scale decisions** where the decision involves changes significant enough to **affect market conditions** and production volumes at a macro level
- The decision is likely to **influence which technologies or suppliers are marginal** in the market
- Consequences extend **beyond the immediate production system** and can shift supply and demand dynamics
- A **consequential LCA approach** is most appropriate, as the goal is to identify the environmental consequences of a decision on the broader system

### Contrast with Situation A:
Situation A typically involves small-scale decisions where market effects are negligible and attributional/accounting approaches suffice. Situation B moves beyond this to system-wide market effects.

### Practical Implication:
In Situation B, the analysis should model **marginal suppliers and technologies**, account for market responses, and potentially include **long-term systemic changes** rather than average or existing production mixes.

This framing is particularly associated with work by **Ekvall (1999/2002)** and subsequent ISO/SETAC guidance on consequential LCA methodology.

Situation B is characterized as a life cycle based decision support context where the consequences of the decision are **so extensive that they overcome thresholds and result in additionally installed or additionally decommissioned equipment/capacity (e.g. production infrastructure) outside the foreground system of the analysed system** — i.e., the decision triggers structural changes in the background system via market mechanisms.

This contrasts with Situation A, where consequences are too small to overcome such thresholds.

The most relevant applications of Situation B include:
- **Policy development**: Forecasting & analysis of the environmental impact of pervasive technologies, raw material strategies, etc.
- **Policy information**: Identifying product groups with the largest environmental improvement potential
- Development of specific, average or generic unit process or LCI results data sets for use in Situation B

*(ILCD Handbook: General Guide for LCA, European Commission – JRC, 2010, p. 40)*

Based on the retrieved sources, Situation B is characterized as follows:

Situation B refers to **life cycle based decision support with consequences that are so extensive that they overcome thresholds and result in additionally installed or additionally decommissioned equipment/capacity (e.g. production infrastructure) outside the foreground system of the analysed system** (ILCD Handbook, p.40).

More specifically, it represents **meso-level and macro-level, strategic ("policy") decision support**, covering applications such as:
- **Policy development**: Forecasting and analysis of the environmental impact of pervasive technologies, raw material strategies, etc.
- **Policy information**: Identifying product groups with the largest environmental improvement potential
- Development of specific, average or generic unit process or LCI results data sets for use in Situation B

(ILCD Handbook, p.40)

As further noted in the context of electromobility LCAs, Situation B addresses potential consequences of a certain decision, but the **extent and nature are very different** from Situation A (micro-level), as Situation B involves consequences large enough to trigger structural changes in the background system via market mechanisms (Hauschild et al., *27 LCA of Electromobility*, p.676).


Question: In an LCI model where no decision support is involved, how should the analysed system be described?

It should describe the analysed system as it is, without including any market consequences in the model, since no decision consequences are related to it.

In an LCI (Life Cycle Inventory) model where **no decision support is involved**, the analysed system should be described as it **actually is** (i.e., as it exists in reality) — reflecting the **actual, real-world situation** rather than a hypothetical or marginal change scenario.

Specifically, the system should be modelled using:

- **Attributional** (or "descriptive") approaches
- **Actual (average) flows and processes** as they occur in the real world
- **Physical/causal relationships** between processes

This contrasts with a **consequential** model, which is used for decision support and describes how the system would **change** in response to a decision (using marginal/substitutable suppliers and technologies).

In summary: the system is described as a **"snapshot" of reality** — what it *is*, not what it *would become* under a given decision.

Based on Source 1 (European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.37):

When no decision support is involved, the LCI model **should describe the analysed system as it is, without including any market consequences in the model**, since no decision consequences are related to it.

Based on the context, when no decision support is involved, the LCI model **should describe the analysed system as it is, without including any market consequences in the model** (as no decision consequences are related to it).

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.37)*


Question: Why is reporting considered a vital element of any LCA, and what can happen without clear documentation and communication?

Reporting is vital because without clear and effective documentation to experts and communication to decision makers, LCAs can be subject to erroneous and misleading use and will not contribute to improving environmental performance.

## Importance of Reporting in LCA

Reporting is considered a vital element of LCA because it serves as the primary means by which the study's **methodology, assumptions, data, and conclusions are made transparent and verifiable** to intended audiences.

---

### Why Reporting is Essential

**Transparency and Credibility**
- Allows third parties to understand exactly how the study was conducted
- Enables peer reviewers and critical reviewers to assess validity
- Builds trust in the results with stakeholders and decision-makers

**Reproducibility**
- Sufficient documentation allows others to replicate or verify the analysis
- Ensures the study can be updated as data improves

**Accountability**
- Links conclusions directly back to the defined goal and scope
- Prevents selective or misleading presentation of results

**Communication of Limitations**
- Proper reporting discloses uncertainties, data quality issues, and assumptions
- Prevents overconfident interpretation of results

---

### Consequences of Poor Documentation and Communication

| Risk | Consequence |
|------|-------------|
| Missing assumptions | Results appear more certain than they are |
| Incomplete system boundaries | Comparisons between studies become invalid |
| Hidden data gaps | Flawed decisions based on incomplete analysis |
| Misleading conclusions | Greenwashing or misguided policy |
| Failed critical review | Study loses credibility or ISO compliance |

---

### ISO 14044 Requirement
ISO standards explicitly require that reports be **complete, accurate, and consistent** with the goal and scope, particularly when results are used for **comparative assertions disclosed to the public**.

In short, without clear reporting, even a technically rigorous LCA can be **misused, misunderstood, or dismissed entirely**.

Reporting is considered a vital element of any LCA for several interconnected reasons:

**Importance of Reporting:**

Reporting goes far beyond simply presenting results. As stated in Guinée et al. (2002, p.426), "the reporting of an LCA therefore implies far more than reporting the results of the LCA. It also embraces reporting the methods used, the data used, the choices made, the procedural context in which the LCA was produced and the exact question and purpose of the LCA." This is critical because "the methods for LCA are manifold, databases often give conflicting figures, and many choices must be made in the course of completing an LCA, the results are highly dependent upon the exact details regarding methods, data and choices."

**Consequences Without Clear Documentation and Communication:**

Without clear and effective documentation and communication, the ILCD Handbook (European Commission – JRC, 2010, p.149) warns that **"LCAs can be subject to erroneous and misleading use and will not contribute to improving environmental performance."**

Additionally, Guinée et al. (2002, p.27) emphasizes that **"a technically excellent LCA without a transparent and unambiguous report will be of very limited value"** — this applies to both external and internal studies alike.

Furthermore, reporting must be tailored to its audience, as the ILCD Handbook (2010, p.372) notes that reporting must consider "any limited technical and LCA methodological understanding of the addressees" to ensure all targeted audiences are appropriately informed.

Reporting is considered a vital element of any LCA because without clear and effective documentation to experts and communication to decision makers, LCAs can be subject to **erroneous and misleading use** and will **not contribute to improving environmental performance**. Reporting shall be objective and transparent, with a clear indication of what has been done.

(ILCD Handbook: General Guide for LCA, p.149)

This is further reinforced by the Guinée Handbook, which states that "a technically excellent LCA without a transparent and unambiguous report will be of very limited value." This applies not only to external studies but also to internal studies, as internal innovation studies can sometimes come to be used outside the company over time. For external studies in particular, third parties need to be able to see which choices and assumptions were made, which parts of the life cycle were excluded, and which data were used.

(Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards, p.27)

Additionally, because LCA methods are manifold, databases often give conflicting figures, and many choices must be made, the results are highly dependent on exact details regarding methods, data, and choices. Therefore, reporting an LCA implies far more than just reporting results — it also encompasses reporting the methods used, data used, choices made, procedural context, and the exact question and purpose of the LCA.

(Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards, p.426)


Question: When multiple crops are harvested in a single year, how should the calculated inventory for that year be distributed among them?

It should be linearly allocated between the crops over the portion of the year that they use or block the land, with no further differentiation between earlier and later months.

## Allocation of Annual Inventory Among Multiple Crops

When multiple crops are harvested within a single year, the annual inventory (inputs, emissions, land use, etc.) should be **allocated among the crops in proportion to the time each crop occupies the land** during that year.

### Key Principle: Time-Based Allocation

The fraction allocated to each crop is calculated as:

$$f_{crop_i} = \frac{t_i}{\sum t_i}$$

where $t_i$ is the **number of days (or weeks/months)** that crop *i* occupies the field during the year.

### Rationale
- Annual inventory items (e.g., soil emissions, background field management) occur continuously throughout the year and cannot be attributed exclusively to one crop.
- Time in the field serves as a **neutral, physically meaningful** allocation key reflecting each crop's share of the annual growing cycle.

### Example
| Crop | Days in Field | Allocation Share |
|------|--------------|-----------------|
| Crop A | 180 days | 180/365 ≈ 49% |
| Crop B | 120 days | 120/365 ≈ 33% |
| Crop C | 65 days | 65/365 ≈ 18% |

### Notes
- Crop-**specific** inputs (e.g., pesticides applied only to one crop) are **directly assigned** without allocation.
- This approach is consistent with guidance in **ecoinvent** methodology and ISO 14044 co-product allocation principles.
- If time data are unavailable, economic or mass-based allocation may serve as alternatives, though time-based is generally preferred for field-level processes.

According to the ILCD Handbook, when more than one crop is harvested per year, the calculated inventory for that year **shall be linearly allocated between these crops over the time of that year that they use the land or block it for other uses**. For simplification, no further differentiation needs to be made between months earlier and later in that year.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.100)*


Question: What two aspects distinguish the three decision-context situations of practical relevance in LCA?

They differ regarding (1) whether the LCI/LCA study is to be used to support a decision on the analysed system, and (2) if so, the extent of changes the decision implies in the background system and other systems via market mechanisms—either small (small-scale, non-structural) or big (large-scale, structural).

In LCA, the three decision-context situations of practical relevance are distinguished by two aspects:

1. **The scale of the decision** (micro-level vs. macro-level) – whether the decision involves a small, marginal change or a large-scale, structural change in the system.

2. **The time horizon** (short-term vs. long-term) – whether the consequences of the decision are considered in the near term or over a longer time perspective.

These two aspects together define the three situations:
- **Situation A**: Small-scale/short-term (marginal changes, short time horizon)
- **Situation B**: Small-scale/long-term (marginal changes, long time horizon)
- **Situation C**: Large-scale/long-term (non-marginal/structural changes, long time horizon)

(As described in the framework by Weidema and colleagues in consequential LCA methodology.)

The two aspects that distinguish the three decision-context situations of practical relevance in LCA are:

1. **Whether the LCI/LCA study is to be used to support a decision** on the analysed system (e.g. product or strategy), and
2. **The extent of changes that the decision implies** in the background system and in other systems caused via market mechanisms — which can be "small" (small-scale, non-structural) or "big" (large-scale, structural).

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.36)*

The three decision-context situations are distinguished by two aspects:

1. **Whether the LCI/LCA study is to be used to support a decision** on the analysed system (e.g. product or strategy), and
2. **If so, the extent of changes that the decision implies** in the background system and in other systems caused via market mechanisms — whether these changes are "small" (small-scale, non-structural) or "big" (large-scale, structural).

(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.36)


Question: Under what circumstance may a chosen weighting set be changed during the course of an LCA study?

It may be changed only if an extension is required because a non-default impact category has been additionally included during the study; otherwise the weighting set should not be changed later.

In Life Cycle Assessment (LCA), weighting sets are generally selected at the outset of a study and should remain consistent throughout. However, a chosen weighting set may be changed (or multiple weighting sets applied) under the following circumstance:

**When conducting a sensitivity analysis or comparative analysis** — specifically, if the results or conclusions of the study are sensitive to the choice of weighting factors, alternative weighting sets should be applied to test the robustness of the conclusions. This is particularly required (or recommended) under **ISO 14044** when the study involves comparative assertions disclosed to the public, where transparency and sensitivity analysis are mandatory.

More precisely, the key circumstance is:

- **If the initially chosen weighting set unduly influences or determines the outcome**, a different (or additional) weighting set should be explored to ensure conclusions are not artifacts of that particular value choice. The ISO 14040/14044 standards emphasize that weighting is value-laden and subjective, so sensitivity to weighting choices must be examined.

In practice, a weighting set might also be changed if:
- The **goal and scope of the study changes** significantly mid-study.
- **Stakeholder requirements or commissioner instructions** change.
- The original weighting set is found to be **inappropriate or inconsistent** with the study's stated values or geographic/temporal context.

The overarching principle is **transparency** — any change in weighting must be clearly documented and justified in the study report.

Based on the provided context, the circumstance under which a chosen weighting set may be changed during the course of an LCA study is addressed in Source 2 (Hauschild et al., LCA: Theory and Practice — 37 LCA Cookbook, p.994):

**The same normalisation and weighting set shall be used for cut-off rules as for results interpretation** — meaning the weighting set must remain consistent throughout. Specifically, rule 14 states: *"If used in support of results interpretation, the same normalisation and weighting set shall be used as for the cut-off rules."*

Additionally, from **Source 4 (Hauschild et al., LCA: Theory and Practice — 10 Life Cycle Impact Assessment, p.193)**, it is noted that if a single weighting set cannot reflect the values of all relevant stakeholders, **several sets of weighting factors may have to be applied**, representing the preferences of the most important stakeholder groups. This implies that multiple weighting sets could be used, but not that a chosen set is arbitrarily changed mid-study.

The context does not explicitly describe a circumstance where a weighting set may be **changed** mid-study. What the sources do indicate is that the weighting set must be consistent with the goal and scope definition (Source 4, p.193) and must align with the intended application of the study (Source 2, p.994). A change would only be warranted if the goal and scope of the study itself changed.

Based on the retrieved context, the circumstance under which a chosen weighting set may be changed during the course of an LCA study relates to **sensitivity analysis**. Specifically, the weighting method is identified as one of the key methodological choices that should be subjected to sensitivity analysis, and the consequences of altering that choice on the results should be calculated.

As stated in Guinée et al.:

> "This checklist includes those (model) choices known to be of major influence on the results of the study: product system specification…; allocation rules; characterisation method; **weighting method**. The consequences of altering the choices vis-à-vis these issues on the results of the LCA should be calculated."
> *(Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards (2002), p.640)*

Additionally, the ILCD Handbook notes that among the methodological choices in an LCA study, the **normalisation basis and weighting set** may be varied as part of scenario or sensitivity investigations:

> "LCI method approaches (and normalisation basis and weighting set, if included)… Even within an LCIA methodology there may be choices to make"
> *(ILCD Handbook: General Guide for LCA (2010), p.378)*

Furthermore, if different stakeholder groups hold different values, **several sets of weighting factors** may need to be applied, effectively changing the weighting set depending on the stakeholder perspective being considered *(Hauschild et al., 10 Life Cycle Impact Assessment, p.193)*.


Question: What are the three approaches illustrated for solving the multifunctionality problem in a process?

Subdivision of the black box unit process, substitution of the not required co-functions (system expansion), and allocation of the inventory to the co-functions.

The three approaches illustrated for solving the multifunctionality problem in a process (as outlined in LCA methodology, particularly in ISO 14044 and guidelines like those from ILCD or ecoinvent) are:

1. **System expansion (substitution)** – Expanding the system boundary to include the additional functions provided by the co-products, thereby crediting the system for avoiding the production of those co-products from alternative sources.

2. **Subdivision (partitioning by physical causality)** – Subdividing the process into sub-processes that can be attributed individually to each function/product, if the process data allow it.

3. **Allocation (partitioning)** – Allocating (distributing) the environmental burdens of the process among the multiple co-products based on a chosen allocation key (e.g., mass, energy content, economic value).

These three approaches are listed in **ISO 14044** in a hierarchical order of preference (system expansion first, then subdivision, then allocation).

Based on the sources provided, the three approaches illustrated for solving the multifunctionality problem in a process are:

1. **Subdivision** of the black box unit process
2. **Substitution/System expansion** of the not required co-functions
3. **Allocation** of the inventory to the co-functions

These three approaches are referenced in the ILCD Handbook figures listed on **p.16 (Source 5)**, specifically:

- *Figure 8*: Solving the multifunctionality problem by **subdivision** of the black box unit process (p.76)
- *Figure 9*: Solving the multifunctionality problem by **substitution** of the not required co-functions (p.78)
- *Figure 11*: Solving the multifunctionality problem by **allocation** of the inventory to the co-functions (p.79)

This is also consistent with **Hauschild et al., p.121 (Source 2)**, which states: *"the preferred solution is subdivision of the concerned process, and if this is not possible, system expansion and, as a last resort, allocation."*

Based on the retrieved sources, the three approaches illustrated for solving the multifunctionality problem in a process are:

1. **Subdivision** – The preferred solution, which involves subdividing the multifunctional black box unit process into its individual operations (ILCD Handbook, p.76; Hauschild et al., p.121).

2. **System expansion** (also referred to as **substitution**) – Used when subdivision is not possible; it involves expanding the system boundary to include or substitute the co-functions not required by the reference flow (ILCD Handbook, p.78–79; Hauschild et al., p.121).

3. **Allocation** – Used as a last resort when neither subdivision nor system expansion is feasible; it involves sharing the environmental burden of the concerned process between its co-functions according to defined criteria (ILCD Handbook, p.80; Hauschild et al., p.121).

These three approaches are explicitly listed in the ISO hierarchy as described in **Hauschild et al., LCA: Theory and Practice, Chapter 9, p.121**, and illustrated in **ILCD Handbook, pp. 76–80 (Figures 8, 9, 10, 11)**.


Question: In the context of LCA studies, what does the term "comparative study" cover?

It covers both assertive and non-assertive studies that compare alternatives.

In LCA, a **comparative study** (sometimes called a **comparative assertion** study) refers to an LCA conducted to **compare two or more product systems, processes, or options** that fulfill the same function (i.e., share the same functional unit), with the purpose of identifying which option has lower environmental impacts.

Key aspects:

- **Same functional unit**: The systems being compared must deliver equivalent function/performance.
- **Purpose**: To support decision-making (e.g., product design, procurement, policy) by ranking alternatives on environmental grounds.
- **Disclosure**: Under ISO 14044, if a comparative study is intended for **public disclosure** (a "comparative assertion disclosed to the public"), it is subject to **mandatory critical review** by an independent panel of experts, to ensure scientific credibility and prevent misleading claims.
- **Scope**: Can cover competing products (e.g., plastic vs. glass packaging), technologies, materials, energy systems, or waste management routes.

The stricter requirements for publicly disclosed comparative studies reflect the potential for such studies to influence consumer or policy choices, making transparency and rigor especially important.

Based on the context provided, the term "comparative study" covers **both assertive and non-assertive studies that compare alternatives**.

As stated in the ILCD Handbook: General Guide for LCA (2010), p.140:

> "The term 'comparative study' covers in this document both cases, i.e. both assertive and non-assertive studies that compare alternatives."

[Source 1: European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.140]

Based on the context, the term "comparative study" covers both **assertive and non-assertive studies that compare alternatives** (European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.140).


Question: When normalisation is applied in LCIA, how are normalised LCIA results calculated, and for what level is the calculation performed separately?

Normalised LCIA results are calculated by dividing the LCIA results by the normalisation basis, done separately for each impact category (for midpoint level approaches) or each area of protection (for endpoint level approaches).

## Normalisation in LCIA

### Calculation of Normalised Results

Normalised LCIA results are calculated by **dividing the characterised impact category indicator result by a normalisation reference (reference value)**:

$$N_k = \frac{S_k}{NR_k}$$

Where:
- **N_k** = normalised result for impact category *k*
- **S_k** = characterised indicator result for impact category *k*
- **NR_k** = normalisation reference (reference value) for impact category *k*

### Normalisation Reference

The normalisation reference typically represents the **total impact of a reference system** (e.g., a person, a region, or the world) for the same impact category — for example, the total annual emissions or resource use of a country or the entire world, expressed per capita or in absolute terms.

### Level at Which Calculation is Performed Separately

The normalisation calculation is performed separately **for each impact category** (i.e., at the **impact category level**).

Each impact category has its own normalisation reference value, so the division is done independently for every individual impact category. This ensures that results across different impact categories are expressed on a comparable, dimensionless scale, while still maintaining the category-by-category structure.

Normalised LCIA results are calculated by **dividing the LCIA results by the normalisation basis**, performed **separately for each impact category** (for midpoint level related approaches) or **area of protection** (for endpoint level related approaches).

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.281)*

Normalised LCIA results are calculated by **dividing the LCIA results by the normalisation basis**, performed **separately for each impact category** (for midpoint level related approaches) or **area of protection** (for endpoint level related approaches).

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 281)*


Question: When inventorying CO2 release caused by land use and land transformation, which emission factors should be used unless more accurate, specific data is available?

The most recent IPCC CO2 emission factors.

When inventorying CO₂ release caused by **land use and land transformation**, the following emission factors should be used as defaults (unless more accurate, specific data is available):

## Default Emission Factors

### Land Transformation
- The **IPCC default values** for changes in carbon stocks associated with land-use change are the standard reference, particularly from the **IPCC Guidelines for National Greenhouse Gas Inventories**.

### Specifically in LCA Context (e.g., ecoinvent / ISO standards)
The commonly referenced default approach uses:

- **Soil organic carbon (SOC) reference values** by climate region and soil type (from IPCC)
- For **above-ground biomass**: IPCC Tier 1 default biomass carbon stock values by vegetation/land-use type and region

### Key Sources Referenced in LCA
- **IPCC 2006 Guidelines** (or 2019 Refinements) — Tier 1 default carbon stock factors for different land-use categories
- **ecoinvent** methodology uses country/region-specific carbon stock data based on these IPCC defaults
- The **PAS 2050** and **GHG Protocol Land Sector** guidance also defer to IPCC Tier 1 defaults

## Summary
**IPCC Tier 1 default carbon stock change factors** (distinguishing soil carbon and biomass carbon, by land-use type, climate zone, and region) should be used as the fallback emission factors when site-specific measured data is unavailable.

Would you like more detail on a specific standard or methodology?

The most recent IPCC CO2 emission factors should be used unless more accurate, specific data is available.

*(Source 5, p.221, chapter 7.4.3.6.3; also confirmed in Source 1, p.224, and Source 3, p.234)*

Based on the retrieved passages, the most recent **IPCC CO2 emission factors** should be used when inventorying CO2 release caused by land use and land transformation, unless more accurate, specific data is available.

As stated in the ILCD Handbook (p. 221): *"For CO2 release caused by land use and land transformation, the use of the most recent IPCC CO2 emission factors shall be used, unless more accurate, specific data is available. Detailed provisions and table with the current IPCC factors: see chapter 7.4.4.1 and annex 13."*

This is also reinforced on p. 224: *"For CO2 release from or binding in soil organic carbon (SOC) caused by land use and land transformation, the use of the most recent IPCC CO2 emission factors shall be used, unless more accurate, specific data is available."*