Question: When developing unit process data sets as deliverables of LCA work, why is the calculation of LCI results required?

Because it serves, together with subsequent characterisation, to quantify the overall completeness and approximate the overall uncertainty of the data set per impact category.

## Why LCI Results Calculation is Required When Developing Unit Process Data Sets

When developing unit process data sets as LCA deliverables, calculating **LCI (Life Cycle Inventory) results** is required for several important reasons:

### 1. **Validation and Quality Assurance**
- Calculating LCI results allows the practitioner to verify that the unit process data set is **mass and energy balanced** correctly
- It helps detect errors, inconsistencies, or missing flows within the unit process before delivery

### 2. **Verification of Completeness**
- Running the LCI calculation confirms that all relevant elementary flows (emissions, resource extractions) are **properly accounted for** across the supply chain connected to the unit process
- It ensures no significant flows have been omitted

### 3. **Compliance with ISO 14044 Requirements**
- ISO 14044 requires that LCI results be calculated and reported as part of a complete LCA study, meaning unit processes must be functional within a **complete system boundary**

### 4. **Enabling Peer Review and Transparency**
- LCI results provide a **traceable and verifiable output** that reviewers and clients can assess against benchmarks or comparable data sets

### 5. **Demonstrating Fitness for Purpose**
- Calculating results confirms the unit process data set **performs correctly** when integrated into a product system, making it usable by others (e.g., in background databases)

### 6. **Identifying Hotspots**
- Even at the unit process development stage, LCI results reveal which flows or upstream processes are most significant, informing **data quality priorities**

---

In essence, the LCI calculation serves as a **functional test** of the unit process data set, ensuring it is complete, balanced, and fit for use in broader LCA studies.

The calculation of LCI results is required when developing unit process data sets as deliverables of LCA work because **it serves, together with subsequent characterisation, to quantify the overall completeness and approximate the overall uncertainty of the data set per impact category**. If normalisation and weighting are included in the definition of the cut-off rules, these are also to be applied.

*(Source 1: ILCD Handbook: General Guide for LCA (2010), p. 273)*

According to the ILCD Handbook, when developing unit process data sets as deliverables of LCA work, the calculation of LCI results is required because **it serves, together with subsequent characterisation, to quantify the overall completeness and approximate the overall uncertainty of the data set per impact category**. If normalisation and weighting are included in the definition of the cut-off rules, these are also to be applied.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.273)*


Question: When a functional unit cannot generally be given for materials and other application-unspecific products, what should be provided instead?

Only the reference flow that includes the main technical specification of the product should be provided.

When a functional unit cannot generally be given for materials and other application-unspecific products, a **declared unit** should be provided instead.

The declared unit is a quantified unit of a product for use as a reference unit in an EPD (Environmental Product Declaration) for products where a functional unit cannot be determined because the product's ultimate application and function are not known at the time of the LCA study. It simply describes the amount of product being assessed (e.g., 1 kg of material, 1 m² of material at a specified thickness) without referencing a specific function or performance level.

For materials and other application-unspecific products where a functional unit cannot generally be given, **only the reference flow that includes the main technical specification of the product should be provided**. In this case, the reference flow is also the **declared unit**, but not the functional unit.

*(Hauschild et al., LCA: Theory and Practice — 37 LCA Cookbook, p.975, item 7:1)*

When a functional unit cannot generally be given for materials and other application-unspecific products, **only the reference flow that includes the main technical specification of the product should be provided**. In this case, the reference flow is also the **declared unit**, but not the functional unit.

*(Hauschild et al., LCA: Theory and Practice — 37 LCA Cookbook, p.975)*


Question: Which types of activities should in principle be inventoried in a system, depending on the included life cycle stages and the system boundary?

Activities such as mining, processing, manufacturing, use, repair and maintenance, transport, waste treatment, and other purchased services linked to the analysed system.

# Activities to be Inventoried in an LCA System

## Core Principle
The system boundary defines which unit processes are included, and **all activities within that boundary must be inventoried** to ensure completeness.

---

## Activities by Life Cycle Stage

### 1. **Raw Material Extraction (Cradle)**
- Mining, drilling, harvesting of natural resources
- Land use and transformation
- Primary processing of raw materials

### 2. **Material Processing & Manufacturing**
- Processing of intermediate materials
- Energy conversion and supply
- Manufacturing/fabrication of the product
- Auxiliary material production

### 3. **Transport & Distribution**
- Transport between all life cycle stages
- Warehousing and storage operations
- Packaging production and use

### 4. **Use Phase**
- Direct energy/water consumption during use
- Consumables and auxiliary inputs
- Maintenance and servicing activities
- Repair and refurbishment

### 5. **End-of-Life (Grave)**
- Collection and transport
- Recycling processing
- Waste treatment (incineration, landfill)
- Reuse activities

---

## Cross-Cutting Activities (all stages)
- **Energy production** (electricity, heat generation)
- **Water supply and treatment**
- **Infrastructure** (buildings, machinery) — if relevant
- **Human labor** — typically excluded but debated
- **Capital goods** — included if significant

---

## Key Considerations for System Boundary
| Boundary Type | Included Stages |
|--------------|-----------------|
| Cradle-to-gate | Extraction → Manufacturing |
| Cradle-to-grave | Extraction → End-of-life |
| Cradle-to-cradle | Includes recycling loops |
| Gate-to-gate | Single process/site only |

---

## Principle of Completeness
Activities should be included when they contribute **meaningfully to environmental impacts**; cut-off criteria (e.g., mass, energy, or environmental relevance thresholds) are applied to exclude negligible processes, but these must be **documented and justified**.

Based on the sources provided, the types of activities that should in principle be inventoried in a system include:

- **Mining**
- **Processing**
- **Manufacturing**
- **Use, repair and maintenance**
- **Transport**
- **Waste treatment**
- **Other purchased services** such as cleaning and legal services, marketing
- **Production and decommissioning of capital goods**
- **Operation of premises** such as retail, storage, administration offices
- **Staff commuting and business travel**

This applies to all activities under normal and abnormal operating conditions related to the analysed system, while **excluding accidents, spills and the like**.

Any exclusion of individual processes or activity types must be justified using cut-off criteria.

*(Sources: ILCD Handbook, p.155; Hauschild et al., LCA Cookbook, p.1008)*

Based on the sources, in principle all processes operated in consequence of the analysed decision should be inventoried. Depending on the system boundary, these activities include:

- **Mining**
- **Processing**
- **Manufacturing**
- **Use, repair and maintenance**
- **Transport**
- **Waste treatment**
- **Other purchased services** such as cleaning and legal services, marketing
- **Production and decommissioning of capital goods**
- **Operation of premises** such as retail, storage, administration offices
- **Staff commuting and business travel**

Any exclusion of individual processes or activity types must be justified using cut-off criteria.

This is stated in two consistent sources:

- **Hauschild et al., LCA: Theory and Practice — 37 LCA Cookbook, p.1008**
- **ILCD Handbook: General Guide for LCA (2010), p.155**


Question: When a unit process inventory item has missing qualitative information, under what condition should the respective flow be created and used in the regular inventory?

Only if it is a product or waste flow; little specified elementary flows (e.g., "Metals to air") shall not be kept in the regular inventory and must be documented in another way.

When a unit process inventory item has missing qualitative information, the respective flow should be created and used in the regular inventory **only if the missing qualitative information is not essential for characterizing the flow's environmental relevance or impact** — more specifically, when the flow can still be reasonably identified and quantified, and the missing qualitative data (such as chemical composition, physical state, or geographic/temporal context) does not prevent its proper linkage to an impact assessment method or does not materially affect the accuracy of the inventory result.

In practical ecoinvent/ISO terms, the condition is typically:

**The flow should be created and included in the regular inventory when the available quantitative and qualitative information is sufficient to uniquely identify the substance/flow and assign it to the correct compartment/category, even if some ancillary qualitative descriptors are absent.** If the missing information makes it impossible to distinguish the flow from others or to correctly characterize its impact, it should instead be treated as an unspecified or proxy flow, or flagged for further data collection rather than introduced into the regular inventory.

Based on the context provided, the respective flow should be created and used in the regular inventory **only if it is a product or waste flow**.

*(Source 1, p.209; Source 2, p.213)*

Based on the sources, when a unit process inventory item has missing qualitative information, the respective flow should be created and used in the regular inventory **only if it is a product or waste flow**.

Little specified elementary flows (e.g., "Metals to air") shall **not** be kept in the regular inventory; instead, this information shall be documented in another way — either as clearly marked flows (e.g., "missing important" or "missing unimportant") that are excluded from aggregation, or documented exclusively in the descriptive information of the data set (e.g., as attached lists).

*(ILCD Handbook: General Guide for LCA (2010), p. 213; also p. 209)*


Question: At which process step can burdens plausibly be allocated to secondary goods, and why?

Burdens can plausibly be allocated only at the process step where a valuable secondary good is produced (Pn), because a waste cannot itself carry any treatment burden and it is inappropriate to attribute all preceding waste treatment processes to the eventually produced secondary good.

## Allocation of Burdens to Secondary Goods

Burdens (environmental impacts) can plausibly be allocated to secondary goods at the **end-of-life (waste treatment / recycling) process step**.

### Why This Step?

At end-of-life, a process typically handles a **primary function** (waste treatment, disposal) while simultaneously producing a **secondary output** (recovered materials, energy, scrap metals, etc.). Two rationales support allocation here:

1. **The secondary good has economic value** – The recycled/recovered material displaces virgin material production, creating a real incentive and market. It is therefore reasonable to assign a share of the processing burden to it, since the process would not be operated (or optimized) without the value of that secondary output.

2. **The process serves two purposes simultaneously** – Waste treatment both disposes of waste *and* produces usable secondary materials. Neither function is entirely "free"; the burden is jointly caused.

### Common Approaches

| Approach | Logic |
|----------|-------|
| **System expansion** (preferred by ISO 14044) | Avoid allocation by crediting the secondary material with avoided burdens of the displaced primary production |
| **Physical allocation** (e.g., mass, energy content) | Split burdens proportionally between primary waste treatment function and secondary material output |
| **Economic allocation** | Split by market value of the secondary good relative to the service |

### Key Point
ISO 14044 discourages arbitrary allocation and recommends **system expansion** first; but when allocation is unavoidable, end-of-life recycling processes are the classic context where allocating *some* burden to the secondary (recovered) good is physically and economically defensible, because the secondary good is a genuine co-product of that step.

Based on Source 1 (ILCD Handbook, p.373), burdens can plausibly be allocated to secondary goods **only at the process step where a valuable secondary good is produced (Pn)** — that is, the final step where the treated waste crosses the "zero market value" border.

The reasoning given is twofold:

1. The waste or end-of-life product is **generated by the first system**, and a waste *per se* cannot carry any burden of treatment.
2. It is considered **inappropriate to attribute all preceding waste treatment processes** (P1 through Pn-1) to the eventually produced secondary good.

Therefore, allocation of burdens to secondary goods can only be justified at that specific process step (Pn) where value is created, not throughout the earlier treatment steps. The procedure requires first modelling the waste/end-of-life management processes until the treated waste crosses the "zero market value" border, and then applying the two-step allocation procedure at that point.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.373)*

Based on the ILCD Handbook, burdens can plausibly be allocated to secondary goods **only at the process step where a valuable secondary good is actually produced (Pn)**.

The reasoning is twofold:

1. The waste or end-of-life product is generated by the first system, and **a waste per se cannot carry any burden of treatment**.
2. It is considered **inappropriate to attribute all preceding waste treatment processes** (P1 through Pn-1) to the eventually produced secondary good.

Therefore, the procedure requires first modelling the waste/end-of-life management and treatment processes until the treated waste crosses the **"zero market value" border**, and only subsequently applying the two-step allocation procedure at that final process step (Pn) where the valuable secondary good emerges.

*(ILCD Handbook: General Guide for LCA (2010), p. 373)*


Question: In an LCA intended to compare two or more products, what is the consequence of not basing the comparison on a valid functional unit that reflects the service provided?

Seriously misleading results may occur, because the functional unit must give an unambiguous definition of the service or function the products provide, and the reference flows must be based on it.

## Consequence of Not Using a Valid Functional Unit in Comparative LCA

If a comparison is not based on a valid functional unit that reflects the service provided, the comparison becomes **invalid and potentially misleading**, specifically:

### Core Problem: Comparing "Apples to Oranges"
The systems being compared will not be delivering **equivalent function or service**, meaning any environmental conclusions drawn are fundamentally flawed.

### Specific Consequences

1. **Biased results** – One product may appear environmentally superior simply because it delivers *less* service per unit analyzed, not because it is genuinely more efficient.

2. **Incorrect decision-making** – Stakeholders (consumers, policymakers, businesses) may make suboptimal or counterproductive choices based on misleading data.

3. **Underestimation or overestimation of impacts** – If quantities are not normalized to equivalent service delivery, total life cycle impacts will not be comparable.

4. **Loss of study validity** – Per ISO 14044, the functional unit must be clearly defined and measurable; failure to do so undermines the scientific and methodological integrity of the study.

5. **Potential for greenwashing** – Results could be selectively reported to favor a particular product without a legitimate basis for comparison.

### Classic Example
Comparing **1 kg of plastic bag** vs. **1 kg of cotton bag** without accounting for the number of uses each provides — the functional unit should reflect *carrying goods a defined number of times*, not just mass.

> **Bottom line:** Without a valid functional unit, the LCA comparison is scientifically meaningless and cannot reliably support conclusions about relative environmental performance.

Based on the context provided, failing to base a comparison on a valid functional unit that reflects the service provided can lead to **seriously misleading results**.

As stated in the ILCD Handbook:

> "When the functional unit does not reflect the service provided or the reference flows are not based on a functional unit, **seriously misleading results may occur**."

The functional unit must give an unambiguous definition of the service or function that the compared products must provide, and only from this definition can the reference flows of the products be properly determined.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 366)*

Based on the retrieved context, failing to base comparisons on a valid functional unit that reflects the service provided can lead to **seriously misleading results**.

As stated in the ILCD Handbook:

> "When the functional unit does not reflect the service provided or the reference flows are not based on a functional unit, **seriously misleading results may occur**."

The handbook further illustrates this with a concrete example: "The chassis of a television set can be made from plastic type A, from metal M or from bio-based material B" — where without a proper functional unit defining the equivalent service, the comparison would be invalid.

Additionally, for comparisons to be meaningful, "the functional unit must give an unambiguous definition of the service or function that the compared products must provide," upon which the reference flows of the products can then be determined.

**(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 366)**


Question: Which section of the document covers solving multifunctionality of processes in attributional modelling?

In the context of LCA methodology documents (such as the ILCD Handbook or ISO 14044), the section covering **solving multifunctionality of processes in attributional modelling** is typically found in the section on **system boundary definition and allocation**, often referred to in the ILCD Handbook as:

**Section on "Multifunctionality and allocation"** — specifically dealing with the hierarchy of approaches:
1. Subdivision/disaggregation
2. System expansion (avoided burden)
3. Allocation based on physical relationships
4. Allocation based on economic value

In the **ILCD Handbook (EC, 2010)**, this is addressed in **Section 7.3** (or the equivalent subsection on multifunctionality under inventory modelling).

If you are referring to a **specific document**, please clarify the title, as the exact section numbering varies by source (e.g., ISO 14044, ILCD Handbook, EPA guidelines, ecoinvent documentation).

Based on the context provided, solving multifunctionality of processes in attributional modelling is covered in **chapter 7.4.2.2** (as referenced in Source 2, p.75 of the ILCD Handbook), which provides "more details on subdivision, partial subdivision, and virtual subdivision."

Additionally, the topic is addressed under the broader **chapter 7** (Life Cycle Inventory analysis), specifically in the section on **"Solving multifunctionality"** as noted on **p.255** of the ILCD Handbook (Source 1), which references the ISO hierarchy detailed in **chapter 6.5.3**.

Based on the context, the guidance on solving multifunctionality in attributional modelling is covered in **chapter 7.4** (specifically referenced as chapter 7.4.2.2 for subdivision details) of the ILCD Handbook. The topic is explicitly addressed starting at **page 255** of the ILCD Handbook: General Guide for LCA (2010), which states:

> "Note that the following chapter provides guidance on solving multifunctionality in attributional modelling only, as the corresponding task in consequential modelling has been addressed already in the chapter 7.2.4 on identifying and describing processes."

Additionally, the process identification procedures for attributional modelling are covered in **chapter 7.2.3** (p. 154, 159, 162) of the ILCD Handbook.


Question: What term describes a process in which additional demand does not change market direction and does not result in additional or reduced capacity of affected processes or systems?

The term you're describing is **"marginal demand"** in the context of LCA — more specifically, this concept is referred to as **"non-marginal"** or, more precisely, the situation describes a **"non-affected"** or **"inframarginal"** condition.

However, in LCA methodology, the specific term used is:

**"Average/non-marginal"** — but the most precise answer here is that this describes a **"constrained market"** or, in consequential LCA terminology, a process/supplier that is **"non-determining"** (i.e., not the marginal supplier).

More specifically, in the context of consequential LCA and market modeling, when additional demand **does not change market direction and does not result in additional or reduced capacity**, this is described as a situation where the technology or process is operating under **"constrained conditions"** — and the relevant concept is that it is **not the marginal technology**.

The precise term most commonly used in this context (particularly in ecoinvent and consequential LCA methodology) is:

**"Constrained market"** — where the marginal supplier is a **constrained/non-expandable** technology, meaning demand shifts to another supplier rather than expanding capacity.

The term specifically describing the condition where additional demand causes **no change** in capacity is a **"non-responsive"** or **"inelastic"** supply situation.

**"Short-term marginal"** processes/systems.

*Source: European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.166*

"Short-term marginal" is the term that describes a process in which additional demand does not change market direction and does not result in additional or reduced capacity of affected processes or systems.

(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.166)


Question: What three elements must a goal definition clearly state to avoid misleading results interpretation in an LCA study?

The comparative character of the study (including any assertions about environmental superiority or equality intended for publication), the reasons for carrying out the study including the decision-context, and who commissioned the study.

In an LCA study, a goal definition must clearly state:

1. **The intended application** – the specific purpose or use for which the study is being conducted (e.g., product improvement, comparative assertion, policy support)

2. **The intended audience** – who the results are directed at (e.g., internal decision-makers, general public, regulatory bodies), as this influences the level of detail, transparency, and critical review required

3. **The reasons for carrying out the study** – the motivation or context behind the study, which helps frame how results should be interpreted and communicated

These three elements are required by ISO 14040/14044 to ensure transparency and prevent misuse or misinterpretation of LCA results.

Based on Source 1 (European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.365), the goal definition must be very clear on three elements to avoid misleading results interpretation:

1. **The comparative character of the LCA study** (e.g., comparing fuel-type A and fuel-type B), including whether assertions about environmental superiority or equality are made and foreseen to be published.

2. **The reasons to carry out the study, including the decision-context** (e.g., supporting governmental decisions on the introduction of new fuel-types).

3. **Who commissioned the study** (e.g., the National Ministry for Transportation).

Based on Source 1 (ILCD Handbook, p.365), a goal definition must be very clear on three elements to avoid misleading results interpretation:

1. **The comparative character of the LCA study** — including whether assertions about environmental superiority or equality are made and if these are foreseen to be published (e.g., "Comparison of the environmental impacts associated with fuel-type A and fuel-type B for use in private cars in Country X")

2. **The reasons to carry out the study, including the decision-context** (e.g., "Support governmental decisions on the introduction of new fuel-types for private cars in Country X")

3. **Who commissioned the study** (e.g., "The National Ministry for Transportation in Country X")

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.365)*


Question: What distinguishes Situation C1 from Situation C2 in life-cycle assessment?

Whether existing benefits outside the analysed system (such as recycling credits) are considered—in Situation C1 they are considered, while in Situation C2 they are not.

In life-cycle assessment (LCA), particularly within the context of **system expansion and substitution** (as described in ISO 14044 and related guidance documents, including work by Weidema and others on multi-output processes), **Situation C1** and **Situation C2** refer to different circumstances for handling co-production or waste treatment allocation:

---

## Situation C1 vs. Situation C2

These situations are described in the context of **determining whether outputs are co-products or wastes**, and how to handle system boundaries accordingly:

### **Situation C1**
- The co-product (or secondary output) **can replace an existing product** on the market (i.e., there is a marginal supplier that is displaced).
- System expansion is straightforward: the system is **credited** for avoiding the production of the substituted product.
- The determining factor is that the **substitute has a clearly identifiable alternative production route**.

### **Situation C2**
- The co-product **cannot be assumed to substitute** a specific existing product, or the market situation is such that the co-product **creates its own demand** (e.g., it is a new product with no direct substitute).
- System expansion is more complex or less applicable, and **allocation by physical or economic parameters** may be more appropriate.
- The distinguishing factor is the **lack of a clearly displaced alternative product**.

---

**In essence**, the key distinction is whether a **substitutable alternative production route exists** (C1) or not (C2), which determines whether system expansion/substitution credit is applicable.

If you are referring to a specific publication or framework, please clarify, as terminology can vary by source.

Based on the provided sources, the key distinction between Situation C1 and Situation C2 is whether interactions with other systems are included in the model.

**Situation C1** accounts for interactions the analysed system has with other systems — for example, crediting existing avoided burdens from recycling. It is used for life cycle-based monitoring that includes indirect effects and existing interactions with background systems (Hauschild et al., p.969; ILCD Handbook, p.43).

**Situation C2** describes an existing system **in isolation**, without accounting for interactions with other systems. It is only used when specifically prescribed by the commissioner's goal of the study (Hauschild et al., p.969; ILCD Handbook, p.71).

A further modelling difference is that for **Situation C2**, multifunctionality **shall always be solved via allocation**, whereas Situation C1 follows the same modelling approach as Situation A (which may use substitution) (ILCD Handbook, p.9).

Both situations are retrospective/accounting in nature and cannot be directly used to inform forward-looking decisions such as purchase decisions or "what if" policy scenarios (ILCD Handbook, p.44).

**Sources:** Hauschild et al., p.969; ILCD Handbook, pp. 8–9, 43–44, 71.

Based on the retrieved sources, Situation C1 and C2 are both sub-types of Situation C ("Accounting"), but they differ in the following key ways:

**Situation C1** describes an existing system **and accounts for interactions it has with other systems** (e.g. crediting existing avoided burdens from recycling). It models the "normal" full life cycle of products, including existing/past interactions between systems. Multifunctionality is handled via **system expansion/substitution** (similar to Situation A). (Hauschild et al., *37 LCA Cookbook*, p.969; ILCD Handbook, p.44)

**Situation C2** describes an existing system **in isolation, without accounting for interactions with other systems** — characterized as "accounting without interactions." Multifunctionality in Situation C2 **shall always be solved via allocation**, applying the detailed allocation guidance provided. (Hauschild et al., *37 LCA Cookbook*, p.969; ILCD Handbook, p.9)

Additionally, from the decision tree perspective, **C1 is the default** unless C2 is specifically prescribed by the commissioner's goal of the study. (Hauschild et al., *7 Goal Definition*, p.71)

In short, the key distinction is whether **interactions with other systems are included in the model**: yes for C1, no for C2 — with corresponding differences in how multifunctionality is handled.


Question: When applying the LCI modelling and method approaches, which aspects differ between Situations A, B, and C, given that the inventory of a unit process is basically identical across them?

What differs is which processes are within the system boundary—especially in the background system—and how the processes are combined to represent the life cycle model and how multifunctionality is solved.

## Key Differences Between Situations A, B, and C in LCI Modelling

When the physical inventory of a unit process is essentially the same, the differences between Situations A, B, and C lie in the **system boundary definition and how co-products/multifunctionality are handled**, particularly regarding **allocation and substitution approaches**. These situations come from the ISO 14044 / ILCD framework for handling multifunctional processes.

---

### Situation A
- The process delivers **one functional output** (no co-products or waste issues)
- No multifunctionality problem exists
- The inventory is directly attributable to the single function
- **No allocation needed**

---

### Situation B
- The process delivers **multiple co-products** (multifunctionality)
- The system can be **expanded** or co-products can be handled by **subdivision**
- Preference is given to **system expansion / substitution** (avoided burden approach)
- If subdivision is not possible, allocation by **physical or economic relationships** is applied

---

### Situation C
- Involves **waste treatment** or processes where one input is a waste (negative economic value)
- The question of **which function bears the burden** differs from Situation B
- The waste-generating system may be credited, or the treatment process carries its own burdens
- Allocation reasoning differs because one "product" is actually a **waste to be treated**

---

### Summary Table

| Aspect | Situation A | Situation B | Situation C |
|--------|------------|------------|------------|
| Multifunctionality | None | Co-products | Waste treatment |
| Allocation needed | No | Yes (or system expansion) | Yes (specific rules for waste) |
| System boundary | Simple | Expanded or partitioned | Waste-specific boundary |
| Substitution credit | N/A | Possible | Specific to waste handling |

The **core inventory data** may be identical, but the **attribution of burdens and credits** changes the final LCI results depending on which situation applies.

Based on the provided sources, when applying LCI modelling and method approaches, the aspects that differ between Situations A, B, and C — given that the unit process inventory is basically identical across them — are:

1. **Which processes are included within the system boundary**, especially in the background system
2. **How the processes are combined to represent the life cycle model**
3. **How multifunctionality is solved**

As stated in Source 1 (ILCD Handbook, p.87):
> "What differs is which processes are within the system boundary, especially in the background system...and how the processes are combined to represent the life cycle model and how multifunctionality is solved."

This is further confirmed in Source 2 (ILCD Handbook, p.8):
> "The main difference between Situation A, B and C lies hence in the selection of the processes that are included in the system boundary and how the life cycle is modelled by connecting them."

Additionally, some specific additional information may be required depending on the Situation, such as **market size and the amount of products involved**, but the core unit process inventories remain essentially the same across all three Situations (ILCD Handbook, p.8 and p.87).

Based on the retrieved passages, while the inventory of a unit process is basically identical across Situations A, B, and C, the aspects that **differ** between them are:

1. **Which processes are included within the system boundary** (especially in the background system), and
2. **How the processes are combined to represent the life cycle model**, and
3. **How multifunctionality is solved**.

As stated in Source 1 (ILCD Handbook, p.87):
> "What differs is which processes are within the system boundary, especially in the background system...and how the processes are combined to represent the life cycle model and how multifunctionality is solved."

This is further reinforced in Source 2 (ILCD Handbook, p.8):
> "The main difference between Situation A, B and C lies hence in the selection of the processes that are included in the system boundary and how the life cycle is modelled by connecting them."

Additionally, some specific **additional information** is required depending on the Situation context (e.g., the amount of products involved and the size of the respective market), and for Situation B specifically, processes affected by large-scale changes must be modelled as **the expected mix of long-term marginal processes** (Source 6, ILCD Handbook, p.92).

**Citations: ILCD Handbook, pp. 8, 87, and 92.**


Question: In life-cycle assessment, how is a market defined, distinguishing it from geographical concepts like countries or regions?

A market is the unit that allows buyers and sellers to exchange any type of goods and services, and it often has a different delimitation than geographical concepts such as countries or regions.

In LCA, a **market** is defined primarily by the conditions under which products (goods or services) are exchanged and substituted for one another, rather than by administrative or geographical boundaries.

Key distinguishing characteristics:

## Definition of a Market in LCA

A market is essentially **a set of suppliers and consumers connected by the possibility of substitution** — where one supplier's output can replace another's for the same functional purpose. It is defined by:

1. **Fungibility/substitutability**: Products within a market are interchangeable for a given function. Electricity on a synchronized grid is the classic example — consumers cannot distinguish between suppliers.

2. **Physical or contractual connectivity**: Suppliers and consumers must actually be able to transact, meaning there must be infrastructure (pipelines, grids, transport routes) or trade relationships linking them.

3. **Marginal supply logic**: The market determines which supplier is **marginal** (i.e., responds to changes in demand), which is critical for consequential LCA.

## How This Differs from Geography

| Concept | Basis |
|---|---|
| Country/Region | Administrative or political boundaries |
| Market | Substitution possibilities and connectivity |

- A **single country** may contain **multiple distinct markets** (e.g., isolated regional grids)
- A **single market** may span **multiple countries** (e.g., the European electricity grid, North American natural gas pipelines)
- Two physically adjacent areas may belong to **different markets** if no substitution pathway exists between them

## Practical Implication

This distinction matters especially in **consequential LCA**, where identifying the correct market determines which technology or supplier is marginal and thus which process actually responds to a change in demand. Using a country boundary as a proxy for a market can introduce significant error if the actual substitution space is broader or narrower than national borders.

In LCA, a market is defined as **"the unit that allows buyers and sellers to exchange any type of goods and services"** (European Commission – JRC, ILCD Handbook, p.128).

This definition is explicitly distinguished from strict geographical or political boundaries such as countries or regions in several important ways:

1. **Markets may be geographically equal to, smaller than, or larger than a country** — they do not automatically align with national borders (ILCD Handbook, p.128–129).

2. **Market boundaries are not exact**, as imports and exports occur across market borders. A useful delimitation is that no *relevant* amounts of such cross-border flows occur, or that they are accounted for when modelling consumption mixes (ILCD Handbook, p.128).

3. **Markets are shaped by multiple factors** beyond geography, including:
   - Political factors (legislation, standards, taxes, subsidies)
   - Cultural recognition by producers and service providers
   - Natural geographical barriers (islands, large distances, climate)
   - Transportation costs relative to product value (Hauschild et al., *LCA: Theory and Practice*, Chapter 9, p.137)

4. Markets can also be **differentiated temporally** (e.g., intraday or seasonal segmentation), not just geographically (ILCD Handbook, p.128).

Thus, while countries or regions are administrative/geographical constructs, markets in LCA are defined by **economic exchange relationships**, which may or may not align with political or geographical boundaries.

Based on the retrieved passages, in LCA a market is defined as **"the unit that allows buyers and sellers to exchange any type of goods and services"** (European Commission – JRC, ILCD Handbook, p.128).

This definition deliberately distinguishes markets from strictly geographical concepts like countries or regions in several important ways:

1. **Markets may be geographically equal to, smaller than, or larger than a country** — natural geographical aspects (islands, large distances, transport barriers, climate) can isolate markets, while political and cultural factors (legislation, competition rules, standards, taxes, subsidies) shape their boundaries (ILCD Handbook, p.128).

2. **The geographical scope of a market is typically not exact**, as imports and exports occur across market borders. A useful working delimitation is that no *relevant* amounts of such cross-border flows occur, or that they are explicitly considered when modelling consumption mixes (ILCD Handbook, p.128).

3. **Market spatial extent varies by product**: some markets are very local (high transport cost relative to product value), while others are global. For example, electrolytic raw copper in Europe is traded on the London Metal Exchange, making it a de facto European average market with no meaningful national sub-markets (ILCD Handbook, p.129; Hauschild et al., *8 Scope Definition*, p.106; *9 Life Cycle Inventory Analysis*, p.137).

4. Markets can also be differentiated **temporally** and by **customer segments**, further separating the market concept from purely geographical notions (ILCD Handbook, p.128).


Question: In modelling reuse, recycling, and energy recovery, between what two things is allocation strictly performed?

Allocation is performed between the two co-functions that the reused, recycled, or recovered good performs—once for the primary product and once for further products as the secondary good—rather than between the first and second life cycles.

In modelling reuse, recycling, and energy recovery, allocation is strictly performed between the **previous life cycle** (or the product system providing the recyclable material) and the **subsequent life cycle** (or the product system using the recovered material/energy).

In other words, allocation is performed between the **first use** (or supplying system) and the **second use** (or receiving system) of the material or energy.

Allocation is strictly performed not between the first and second life cycle, but between the **two co-functions** that the reused, recycled, or recovered good performs — once for the primary product and once for further products as the secondary good.

*(ILCD Handbook: General Guide for LCA, 2010, p. 345)*

Based on the ILCD Handbook, allocation is strictly performed **not between the first and second life cycle**, but between the **two co-functions** that the reused, recycled, or recovered good performs — once for the **primary product** and once for **further products as the secondary good**.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.345)*


Question: In end-of-life recycling models, which process steps have their related inventories assigned to the analysed system?

The process steps that condition, modify, transport, etc. the end-of-life products or waste until the valuable function (e.g. a recycled metal bar) is available in a quality and at a place where it supersedes an alternative production are within the system boundary, so their inventories are assigned to the analysed system.

In end-of-life (EoL) recycling models, the process steps whose inventories are assigned to the analysed system depend on the specific recycling approach used, but the general principle is:

## Process Steps Assigned to the Analysed System

### Collection & Sorting/Pre-processing
- **Collection** of end-of-life products
- **Sorting and dismantling**
- **Pre-processing / shredding / separation**

These steps are consistently assigned to the system producing the waste (the analysed system), as they are necessary to handle the material at end of life.

### Recycling/Reprocessing (partially, depending on model)
- In some models (e.g., the **Recycled Content method / cut-off approach**), the reprocessing step is **not** assigned to the analysed system — the system "cuts off" at the point of waste generation.
- In other models (e.g., **End-of-Life recycling credit / avoided burden approach**), the reprocessing **and** the credit for avoided primary production are assigned to the analysed system.

## Summary by Common Model

| Model | Steps assigned to analysed system |
|---|---|
| **Cut-off (recycled content)** | Collection, sorting, pre-processing (up to scrap handover) |
| **Avoided burden / EoL credit** | Collection, sorting, pre-processing, reprocessing **minus** credit for substituted primary material |
| **Closed-loop substitution (EN 15978 / ISO 21930)** | Collection, sorting, reprocessing, with substitution credit |

The **key boundary** is typically at the point where the waste material becomes a **secondary raw material** (the "end of waste" point), after which responsibility may shift to the next system.

Based on the context provided, in end-of-life recycling models, the total inventory assigned to the analysed system includes **all processes up to the level of the quality of the primary material, energy carrier or part as obtained also later via recycling, plus all recycling and waste treatment steps** (including the repeated recycling processes and the disposal that contribute to the total inventory).

However, it explicitly **excludes** any of the processes from the manufacture and use of the products made from the material, energy carrier or part, because those processes are not physically related to the production of the later reused/recycled/recovered material, energy carrier, or part.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.1, Source 6)*

Based on the retrieved passages, in end-of-life recycling models, the total inventory assigned to the analysed system includes:

- **All repeated recycling processes**, and
- **The disposal** contribution to the total inventory.

Specifically, this total inventory includes **all processes up to the level of the quality of the primary material, energy carrier or part** as obtained also later via recycling, **plus all recycling and waste treatment steps**.

It does **not** include any of the processes from the manufacture and use of the products made from the material, energy carrier or part, because those processes are not physically related to the production of the later reused/recycled/recovered material, energy carrier, or part.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.1 [Source 6])*


Question: Why are errors of below one order of magnitude considered worse, and what are two sources of such errors?

They are worse because they can more easily pass unnoticed while still making the data and conclusions invalid. Two sources are the differing regional handling of the "." and "," decimal separators, and unit conversion errors from using different unit systems (e.g., Imperial to SI).

## Errors Below One Order of Magnitude in LCA

### Why They Are Considered Worse

Errors below one order of magnitude (i.e., errors less than a factor of 10) are considered **more insidious and dangerous** than larger errors because:

- **Large errors are obvious** — mistakes of multiple orders of magnitude are typically caught during review, sanity checks, or comparison with literature values, as they produce clearly unrealistic results.
- **Small-to-moderate errors are plausible** — errors within one order of magnitude fall within a range that *looks reasonable*, making them much harder to detect. They can pass unnoticed through quality checks while still significantly distorting results and conclusions.

In other words, they are "worse" not in absolute magnitude but because they are **invisible errors** that silently undermine the reliability of the study.

---

### Two Common Sources of Such Errors

1. **Incorrect or imprecise activity data** — Using proxy data, outdated figures, or data from a different geography/technology that differs from the actual system by a factor of 2–5 (e.g., using average grid electricity instead of the actual energy mix used by a facility).

2. **System boundary errors / missing processes** — Omitting processes or life cycle stages (e.g., upstream raw material extraction or end-of-life treatment) that each contribute modestly but cumulatively shift results by a factor of 2–10 without triggering obvious implausibility.

Errors below one order of magnitude are considered worse because **they can much more easily pass unnoticed, while still rendering the data and conclusions invalid**.

Two sources of such errors are:

1. **The use of "." and "," as decimal separators**, which are handled differently in different regions and countries.
2. **Unit conversion errors** related to using different unit systems (e.g., Imperial system to SI).

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.203)*

Based on Source 1 (ILCD Handbook, p.203), errors of below one order of magnitude are considered worse because **they can much more easily pass unnoticed, while still rendering the data and conclusions invalid**.

Two sources of such errors identified in the same passage are:

1. **The use of "." and "," as decimal separators**, which are handled differently in different regions and countries.
2. **Unit conversion errors** related to using different unit systems (e.g., Imperial system to SI).

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.203)*


Question: In which part of an LCA data set should the documentation of review findings be placed, and why?

It belongs to the "Review" part, because it does not relate to the documentation of the object of the data set.

## Placement of Review Findings in an LCA Data Set

Review findings should be documented in the **administrative information** section (or "data set information / review" section) of an LCA data set — for example, in the `<review>` field within the **ecospold2** format or the equivalent structure in **ILCD format** (`<dataSetInformation>` → `<reviewers>` / `<review>`).

### Why This Placement?

1. **Transparency and traceability**: Administrative information is the designated location for provenance, quality, and validation metadata. Placing review findings here ensures users can immediately assess the data set's credibility and review status without confusing it with the underlying process or flow data.

2. **Separation of concerns**: LCA data set formats distinguish between:
   - *Technical content* (process inputs/outputs, exchanges, characterization factors)
   - *Administrative/quality metadata* (who created it, when, under what review)

   Review findings belong to the latter category.

3. **Conformance with standards**: Both **ISO 14044** and data format standards (ILCD, ecospold) explicitly provide dedicated fields for review information in the administrative section, ensuring interoperability and consistent interpretation across tools and databases.

4. **User guidance**: Decision-makers and practitioners typically check administrative metadata first to judge data quality; locating review findings there supports informed data selection.

In summary, the administrative information section is the correct location because it is structurally designated for quality and validation metadata, keeping technical data separate while ensuring full transparency.

Based on the ILCD Handbook, the documentation of review findings should be placed in the **"Review" part** of an LCA data set, and **not** in the documentation section.

As stated in the ILCD Handbook (p.336):

> "The documentation of the review findings belongs to the 'Review' part, since it does not relate to the documentation of the object of the data set."

The rationale is clear: review findings concern the **review process itself**, not the substance or content of what the data set describes. Since documentation is meant to capture information about the object of the data set (supporting transparency and reproducibility of the inventory), review findings are categorically distinct and therefore belong under the "Review" part of the data set structure.

Based on Source 4 (ILCD Handbook, p.336):

The documentation of review findings should be placed in the **"Review" part** of an LCA data set — not in the documentation section — because "it does not relate to the documentation of the object of the data set."

This is further supported by the broader framework described in Source 2 (ILCD Handbook, p.334), which distinguishes "Review" as a separate capture of "all review aspects" from "Documentation," which covers the extent and detail of information needed to support transparency and reproducibility of the data set itself.

*(ILCD Handbook: General Guide for LCA (2010), p.336)*


Question: What does Situation A refer to in the context of LCA decision support?

Situation A refers to decision support directly or indirectly related to informing the purchase of products already offered in the market, or to informing the design/development of products foreseen to enter the market, where the product can be assumed to be produced only as a consequence of the decision being supported by the LCI/LCA study.

In the context of LCA decision support, **Situation A** refers to a decision situation involving **changes within an existing system** — typically a **marginal or small-scale change** where the decision affects only part of the production system without fundamentally restructuring it.

More specifically, Situation A (as described by Weidema and others in the context of consequential LCA and decision support frameworks) refers to situations where:

- The decision concerns a **small change** relative to the total market/system
- **Marginal suppliers** (i.e., the suppliers most sensitive to changes in demand) are the relevant ones to model
- The system is essentially **constrained** or operating within existing capacity

This is contrasted with **Situation B**, which involves **large-scale or structural changes** that affect the entire system or market, where average or transformational data may be more appropriate.

The distinction is important for determining which type of LCI data (marginal vs. average) and which modeling approach (attributional vs. consequential) is most appropriate for the decision at hand.

Situation A refers to **"Micro-level decision support"** — it applies when an LCA is used to support decisions where the consequences on the background system are **none or small-scale**. It covers decision support directly or indirectly related to informing the purchase of products already offered in the market, or informing the design/development of products foreseen to enter the market. In this context, the product can be assumed to be produced only as a consequence of the decision being supported by the LCA study.

Situation A applies to applications such as:
- Identification of Key Environmental Performance Indicators (KEPI) for Ecodesign/simplified LCA
- Weak point analysis of a specific product
- Detailed Ecodesign/Design-for-recycling

In general, Situation A is best suited for analysing **short-term effects** at an operational level (e.g., comparison of two specific products).

*(Sources: Hauschild et al., LCA: Theory and Practice — 37 LCA Cookbook, p.967–968; European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.39; Hauschild et al., LCA: Theory and Practice — 27 LCA of Electromobility, p.676)*

Based on the retrieved sources, **Situation A** in LCA refers to **"Micro-level decision support"** — specifically, decision support directly or indirectly related to informing the purchase of products already offered in the market, or informing the design/development of products foreseen to enter the market. It applies when there are **none or small-scale consequences** on processes of the background system or other systems, and when the study is intended to support decisions on alternatives with better or worse environmental performance.

As stated in the ILCD Handbook:
> "Situation A refers to decision support directly or indirectly related to inform the purchase of products that are already offered in the market. Or to inform the design / development of products that are foreseen to entering the market. Accordingly, the product can be assumed to be produced only as consequence of the decision to be supported by the LCI/LCA study."
*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.39)*

Situation A covers applications such as:
- Identification of Key Environmental Performance Indicators (KEPI)
- Weak point analysis of a specific product
- Detailed Ecodesign/Design-for-recycling

*(Hauschild et al., LCA: Theory and Practice — 37 LCA Cookbook, p.967)*


Question: In life-cycle assessment, what does the term "cut-off" refer to?

The omission of not relevant life cycle stages, activity types (e.g. investment goods, storage), specific processes and products (e.g. re-granulating of internally recycled polymer production waste before re-melting), and elementary flows from the system model.

In life cycle assessment (LCA), **"cut-off"** refers to a criterion or rule used to decide which processes, flows, or life cycle stages can be excluded from the system boundary without significantly affecting the results.

Specifically, it involves setting thresholds (based on **mass, energy, or environmental relevance**) below which inputs or outputs are omitted from the study. For example, if a material contributes less than 1% of the total mass and is not considered environmentally significant, it may be "cut off" (excluded) from the inventory.

It also refers specifically to the **"cut-off approach"** (or cut-off allocation method) used in handling **recycled materials**: under this convention, the original producer of a material bears no credit or burden for recycling at end-of-life, and the user of recycled/secondary material receives it "burden-free" (i.e., the upstream burdens of primary production are cut off). This is one of the most common approaches in databases like ecoinvent.

"Cut-off" refers to the omission of not relevant life cycle stages, activity types (e.g. investment goods, storage), specific processes and products (e.g. re-granulating of internally recycled polymer production waste before re-melting) and elementary flows from the system model. Cut-offs are quantified in relation to the percentage of environmental impacts that is approximated to be excluded via the cut-off (e.g. "95%" relates to cutting off about 5% of the total environmental impact (or of a selected impact category)).

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.102)*

Based on the retrieved passages, in life cycle assessment, **"cut-off" refers to the omission of not relevant life cycle stages, activity types (e.g. investment goods, storage), specific processes and products, and elementary flows from the system model.**

Cut-offs are quantified in relation to the percentage of environmental impacts that is approximated to be excluded (e.g. "95%" relates to cutting off about 5% of the total environmental impact or of a selected impact category). Cut-offs are typically introduced because of data deficiency and general time and resource constraints on data retrieval, and can only be justified if the omitted elements are insignificant to the outcome of the LCI/LCA study.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.102–103; Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards (2002), p.444)*


Question: In the context of consequential modelling within LCA, what issue is addressed in the section on solving multifunctionality of processes?

Solving the multifunctionality of processes in consequential modelling.

In consequential LCA, the section on solving multifunctionality of processes addresses the issue of **how to handle processes that deliver more than one function (co-products or by-products)** — i.e., how to determine which other processes in the background system are affected when demand for one of the functions changes.

Specifically, the core problem is: when a process produces multiple outputs (e.g., a refinery producing both gasoline and diesel, or a slaughterhouse producing meat and hide), and you only need one of those outputs for your study, you must decide **which processes are displaced or expanded** as a consequence of changing demand for that one function.

The key issues addressed include:

1. **Identifying whether co-products are constrained by the system** (i.e., whether increasing one output necessarily increases the other) — distinguishing between **constrained/coupled** and **unconstrained** co-production.
2. **Determining the appropriate substitution/displacement approach** — identifying which alternative process supplies the same function in the market, so that the displaced process can be credited or debited.
3. **Avoiding allocation** (which is a attributional approach) in favor of **system expansion or substitution**, consistent with the consequential paradigm.
4. **Handling waste treatment** and whether a process is a supplier or receiver of a function.

The fundamental principle is that multifunctionality is resolved by identifying the **marginal supplier** of each co-product and modeling the **economic consequences** of changes in demand, rather than mathematically partitioning impacts between co-products.

In the context of consequential modelling within LCA, the section on solving multifunctionality addresses the identification of **relevant consequences and related processes** for cases of multifunctionality. Specifically, it covers multifunctionality in Situations A, B, and C1, processes affected by "big" changes (large-scale consequences) in Situation B, and "assumption scenarios" in Situation B where consequential modelling is included.

Notably, the ILCD Handbook explains that in consequential modelling, solving multifunctionality is addressed at the stage of **identifying and describing processes** (rather than as a subsequent step as in attributional modelling), because this step directly affects which processes are to be included in the model.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 255 and p. 164)*

Based on the context provided, in consequential modelling within LCA, the section on solving multifunctionality addresses the **identification and description of processes** — specifically, that in consequential modelling, solving multifunctionality directly affects which processes are to be included in the model. Unlike attributional modelling where solving multifunctionality is a subsequent step after process identification, in consequential modelling this step is integrated into the earlier phase of identifying and describing processes, as it determines the very composition of the system model.

As stated in the ILCD Handbook:

> "Note that the following chapter provides guidance on solving multifunctionality in attributional modelling only, as the corresponding task in consequential modelling has been addressed already in the chapter 7.2.4 on identifying and describing processes. This was necessary as in consequential modelling this step directly affects the processes to be included in the model, i.e. is not a subsequent step as in attributional modelling."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 255)*


Question: What two situations can cause an LCA study to produce misleading conclusions?

When elements of the goal and scope definition are performed in a way that leads to misleading results, and when the results are interpreted in a way that is not in accordance with the goal of the study or how the analysis was scoped.

In Life Cycle Assessment (LCA), two key situations that can cause misleading conclusions are:

1. **Incorrect or inappropriate system boundary definition** – If the system boundaries are drawn too narrowly (cut-off errors) or inconsistently, important upstream or downstream processes may be excluded, leading to an incomplete picture of the true environmental burdens. This can make a product or process appear more (or less) environmentally favorable than it actually is.

2. **Poor or unrepresentative inventory data (data quality issues)** – If the life cycle inventory (LCI) data used are inaccurate, outdated, geographically inappropriate, or not representative of the actual processes being studied, the results will be skewed. This can lead to incorrect conclusions about which product or system has lower environmental impacts.

These two issues—flawed scope/boundaries and poor data—are widely recognized as the primary sources of misleading LCA results.

Based on the context provided, two situations that can cause an LCA study to produce misleading conclusions are:

1. **Narrowing the scope/omitting relevant impact categories**: When a study is defined too narrowly (e.g., as only a carbon footprint study or energy flow analysis), serious misleading may occur by omitting some of the impacts that the system has. This is particularly problematic when two technologies that differ in their pattern of environmental impacts are being compared. *(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.368)*

2. **Transferring conclusions beyond their valid context**: When conclusions drawn from a specific country or situation are applied to another country or context where the underlying conditions (e.g., wastewater treatment practices, appliance efficiency) are not representative, the conclusions will most likely not be valid. *(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.375)*

Based on the retrieved passages, two situations that can cause an LCA study to produce misleading conclusions are:

1. **Limiting the scope/impact categories covered**: When an LCA focuses only on certain environmental flows (e.g., only water and energy use) while omitting other relevant impacts, misleading results can occur — especially when comparing two technologies that differ in their pattern of environmental impacts. For example, focusing only on water and energy use when comparing high pressure cleaners A and B would favour Cleaner B, but would be misleading if detergent-related impacts are significant (ILCD Handbook, p. 368).

2. **Results or conclusions being applied beyond the scope of the specific study**: Misinterpretations occur when recommendations are used beyond the scope of the specific LCA study or beyond what is supported by the outcomes, particularly when the target audience has a limited technical or methodological understanding (ILCD Handbook, p. 304).


Question: How can relevant specific emissions that escape previous assessment steps, such as particle or dioxin emissions, mostly be identified?

By including all legally regulated emissions for that or similar process types, or through expert judgement drawing on know-how for these or similar processes.

## Identifying Specific Emissions Escaping Previous Assessment Steps

Relevant specific emissions such as **particle emissions** or **dioxin emissions** that escape earlier assessment steps can mostly be identified through:

### **Site-Specific Measurements / Direct Emission Measurements**
- Stack measurements and monitoring at emission sources
- Continuous or periodic emission monitoring programs
- Ambient air quality measurements near facilities

### **Key Approaches:**

1. **Literature and Database Review**
   - Reviewing substance-specific emission factors from scientific literature
   - Consulting specialized databases (e.g., EMEP/EEA emission inventory guidebooks)

2. **Material/Substance Flow Analysis**
   - Tracking specific substances through the production chain to identify where they may escape accounting

3. **Regulatory Emission Inventories**
   - National/regional pollutant release and transfer registers (e.g., E-PRTR in Europe)
   - Industry-reported emission data

4. **Characterization Factor Databases**
   - Consulting impact assessment databases that flag substances with high characterization factors but low reporting frequency

5. **Expert Knowledge & Process Knowledge**
   - Engaging process engineers or industry experts familiar with specific emission sources
   - Technology-specific emission profiles

### **Practical Note**
In LCA, these emissions are often captured through **site-specific data collection** or **primary data gathering** when generic background databases fail to represent specific process conditions adequately.

The key principle is that **direct measurement** at the process level remains the most reliable method for capturing such otherwise overlooked emission categories.

Relevant specific emissions that escape previous assessment steps can mostly be identified by **including all legally regulated emissions for that or similar process types**, or are **identified by expert judgement, drawing on know-how for these or similar processes**.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.292)*

According to the ILCD Handbook, relevant specific emissions that escape previous assessment steps (such as particle emissions in fuel oil heating processes, or dioxin emissions in scrap melting and waste incineration processes) can mostly be identified by **including all legally regulated emissions for that or similar process types**, or are **identified by expert judgement, drawing on know-how for these or similar processes**.

(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.292)


Question: What distinguishes Situation C1 from Situation C2 in life-cycle inventory accounting?

In Situation C1, existing interactions with other systems (such as recycling benefits or avoided production for co-products) are included in the LCI model, whereas Situation C2 accounts for the analysed system in isolation.

In life-cycle inventory (LCI) accounting, the distinction between **Situation C1** and **Situation C2** relates to how **waste processing** and **recyclability** are handled at the end of a product's life — particularly in the context of the **European Commission's Product Environmental Footprint (PEF)** / **EF (Environmental Footprint)** methodology and related ISO/CEN frameworks for circular economy allocation.

---

### **Situation C1 – Waste processing with no recyclable material recovered**
In C1, the material undergoes **waste treatment/processing** (e.g., incineration, landfill) **without recovery of a secondary material or energy that displaces a primary equivalent**. The burden of waste processing is borne by the product system. There is no credit given because nothing of value is recovered to substitute for a virgin/primary input elsewhere.

---

### **Situation C2 – Waste processing that yields a recyclable/recoverable output**
In C2, the waste processing step **produces a secondary material or energy** that can substitute for a primary material or energy source elsewhere in the economy. Here, the system must account for:
- The **burden** of the waste treatment process itself, AND
- A **credit** (avoided burden) for the secondary material/energy that displaces primary production.

The allocation formula (often the **circular footprint formula, CFF**) is applied to split burdens and credits between the supplying product system and the receiving (next use) system.

---

### **Key Distinction**
| | C1 | C2 |
|---|---|---|
| Output of waste processing | No recoverable secondary material/energy | Recoverable secondary material or energy |
| Credit applicable? | No | Yes (avoided primary production) |
| CFF allocation | Not applicable (pure end-of-life burden) | Applied to share burdens/credits |

In essence, **C1 is a pure waste/disposal situation**, while **C2 involves value recovery**, triggering allocation between the current product system and future users of the recovered material.

Based on the provided sources, the key distinction between Situation C1 and C2 is:

**Situation C1 ("Accounting with interactions")** accounts for an existing system **including** its interactions with other systems — for example, crediting avoided burdens from recycling or indirect effects under Environmental Management Systems. It applies system expansion/substitution to handle multifunctionality, independently of the absolute amount involved (Hauschild et al., p.969; ILCD Handbook, p.9).

**Situation C2 ("Accounting without interactions")** describes an existing system **in isolation**, without accounting for any interaction with other systems. Multifunctionality in C2 is always solved via **allocation** rather than substitution (Hauschild et al., p.969; ILCD Handbook, p.9).

As stated in the ILCD Handbook (p.9): *"For Situation C2, the life cycle is equally modelled as in Situation A, but multifunctionality shall always be solved via allocation."*

C1 is the default unless C2 is specifically prescribed by the commissioner's goal of the study (Hauschild et al., p.71).

Based on the sources, the key distinction between Situation C1 and Situation C2 is whether interactions with other systems are included in the accounting:

**Situation C1 — "Accounting with interactions"** describes an existing system while accounting for its interactions with other systems (e.g., crediting existing avoided burdens from recycling). It covers applications such as monitoring environmental impacts of a nation, industry sector, or product group, corporate environmental reporting, and development of LCI results data sets. Multifunctionality is solved via **substitution/system expansion**, as in Situation A, independently of the absolute size of the system (Hauschild et al., *37 LCA Cookbook*, p. 969; ILCD Handbook, p. 9).

**Situation C2 — "Accounting without interactions"** describes an existing system **in isolation**, without accounting for interactions with other systems. It applies to accounting studies where the goal definition explicitly excludes any interaction with other systems. Multifunctionality shall **always be solved via allocation** (Hauschild et al., *37 LCA Cookbook*, p. 969; ILCD Handbook, p. 9).

Importantly, C1 is the default — *"C1 is used unless C2 is specifically prescribed by the commissioner's goal of the study"* (Hauschild et al., *7 Goal Definition*, p. 71).


Question: What principle should guide the level of differentiation of flow data sets in an inventory relative to LCIA methods?

The differentiation of flow data sets should be no finer than supported by state-of-the-art LCIA methods and no coarser than required to capture differences in the LCIA results, keeping the number of flows as low as reasonably possible without relevantly affecting impact assessment.

The principle that should guide the level of differentiation of flow data sets in an inventory relative to LCIA methods is **consistency** (or correspondence) between the inventory and the impact assessment method — specifically, the inventory flows should be differentiated **to the same degree (but not more) as the LCIA characterization factors can distinguish between them**.

More precisely:

- If an LCIA method applies **different characterization factors** to a substance depending on certain properties (e.g., emission compartment, geographic region, temporal profile, chemical species), then the inventory flows should be **differentiated accordingly** to capture those distinctions.
- Conversely, if the LCIA method assigns the **same characterization factor** regardless of a particular distinction (e.g., it does not differentiate between emissions to urban air vs. rural air), there is **no benefit** in differentiating the inventory flows to that level — it adds complexity without affecting results.

This principle avoids both **under-differentiation** (losing information that LCIA methods could use) and **over-differentiation** (creating unnecessary complexity with no impact on results). It ensures that the granularity of elementary flow data sets is **fit for purpose** relative to the characterization factors available.

The level of differentiation of flow data sets in an inventory should be guided by the principle of **compatibility** between the collected elementary flows and the LCIA methods to be applied. Specifically, if spatially differentiated LCIA methods are chosen, spatial information for elementary flows (e.g., nation name, watershed ID, or GIS grid cell coordinates) must be collected in the inventory in a manner compatible with those methods. Conversely, if spatially generic LCIA methods are used, such differentiation may not be necessary.

*(Hauschild et al., LCA: Theory and Practice — 8 Scope Definition, p.113)*

Based on the context, the principle that should guide the level of differentiation of flow data sets in an inventory relative to LCIA methods is that the spatial information collected for elementary flows in the life cycle inventory analysis must be **compatible** with the LCIA methods chosen.

Specifically, if spatially differentiated LCIA methods are used, it is important to collect spatial information for the elementary flows (e.g., name of nation, watershed ID, or grid cell defined by GIS coordinates) that is compatible with these methods. Many popular LCIA methods are still spatially generic, but spatially differentiated methods have increased in numbers and quality over the years.

Additionally, the practitioner is responsible for ensuring that inventory elementary flows are correctly linked with the LCIA factors, supported by using the **same nomenclature and flow data sets** across inventory and impact assessment.

*(Hauschild et al., LCA: Theory and Practice — 8 Scope Definition, p.113; European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.277)*


Question: In life cycle inventory analysis, where can confidential information be placed so that only critical reviewers can access it under confidentiality?

In a separate "confidential report" that is made accessible only to the critical reviewers under confidentiality.

In life cycle inventory analysis, confidential information can be placed in a **confidential annex** (or confidential appendix) to the LCA report. This annex is made available only to critical reviewers (third-party reviewers) under confidentiality agreements, while the main report accessible to the public or other stakeholders contains only non-confidential information.

This approach is consistent with ISO 14044 guidelines, which allow for the protection of sensitive business data (such as proprietary process data, trade secrets, or commercially sensitive inventory data) while still enabling a rigorous and transparent critical review process.

Confidential information can be placed in a **separate "confidential report"** that is made accessible only to the critical reviewers under confidentiality.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.204 and p.318; Hauschild et al., LCA: Theory and Practice, p.1000 and p.144)*

Based on the sources provided, confidential information can be placed in a **separate "confidential report"** that is made accessible only to the critical reviewers under confidentiality.

As stated in the ILCD Handbook: "To ensure the necessary transparency for review, confidential information can be documented in a separate 'confidential report' that is made accessible only to the critical reviewers under confidentiality" (ILCD Handbook, p.204).

This is further confirmed in the reporting provisions: "VI) MAY - Confidential report: If prepared, the confidential report shall contain all those data and information that is confidential or proprietary and cannot be made externally available. It shall however be made available to the critical reviewers under confidentiality" (ILCD Handbook, p.318).

Additionally, from Hauschild et al.: "Confidential information can be documented in a separate, complementary report that is not published but only made available to the reviewers under confidentiality" (LCA Cookbook, p.1000).

Similarly, for company internal confidential data, the LCA practitioner may report "any confidential data of importance to the study in a special appendix to the report that is only accessible to a selected group of people (typically including members of a peer review panel)" (Hauschild et al., Chapter 9, p.144).


Question: In life-cycle assessment, what condition causes the provision of an additional good or service to fall under Situation B rather than Situation A?

When the annually provided amount is larger than the average replacement rate of the installed capacity of the superseded alternative good or service.

In LCA, the distinction between **Situation A** and **Situation B** (as defined in ISO 14044 and elaborated in guidance documents like the ILCD Handbook) hinges on whether the background system can respond to a change in demand:

- **Situation A** applies when the **background (market) system is able to respond** to the additional demand — i.e., there is a marginal supplier or unconstrained capacity, so the additional good or service is provided by an **unconstrained, expandable process**. The system can deliver more output without being limited by a fixed capacity constraint.

- **Situation B** applies when the **background system is constrained** and **cannot increase its total output** to meet the additional demand. The supply of the co-product or good is **fixed** (e.g., by a fixed-output process or a constrained market), so obtaining more of it means **diverting it from another use** — i.e., it displaces or substitutes for what that diverted supply would otherwise have provided. The additional provision therefore causes a substitution effect rather than an expansion of production.

In short, the condition that places the situation in **Situation B** is that the **production volume of the process providing the good is fixed (constrained)**, so an increased demand for one of its outputs cannot be met by expanding production but only by reallocating output away from another user, triggering a substitution/displacement effect.

Based on the sources provided, the condition that causes a provision to fall under **Situation B** rather than Situation A is when **the consequences of the analysed decision alone are large enough to overcome related thresholds and/or other constraints, resulting in large-scale consequences in the installed production capacity outside the foreground system**.

More specifically, this occurs when the annual additional demand or supply triggered by the analysed decision **exceeds the capacity of the annually replaced installed capacity** of the additionally demanded or supplied process, product, or broader function.

As stated in the ILCD Handbook:

> "Where a study cannot initially be clearly assigned to either Situation A or B...the guiding criteria shall be whether the consequences of the analysed decision alone are big enough to overcome related thresholds and/or other constraints and result in large-scale consequences in the installed production capacity outside the foreground system. Then: Situation B. If not: Situation A."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.48)*

Additionally, regarding multifunctionality specifically: if no functionally equivalent alternative processes exist, or they are not operated to a sufficient extent, "the study is in fact a Situation B type study, as this implies large-scale consequences on other systems."

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p.91)*

Based on the retrieved passages, a study falls under **Situation B** rather than Situation A when **the consequences of the analysed decision alone are big enough to overcome related thresholds and/or other constraints and result in large-scale consequences in the installed production capacity outside the foreground system**.

Specifically, this occurs when the annual additional demand or supply triggered by the analysed decision **exceeds the capacity of the annually replaced installed capacity** of the additionally demanded or supplied process, product, or broader function — meaning new or decommissioned production infrastructure is added or removed outside the foreground system.

As stated in the ILCD Handbook:

> "Where a study cannot initially be clearly assigned to either Situation A or B… the guiding criteria shall be whether the consequences of the analysed decision alone are big enough to overcome related thresholds and/or other constraints and result in large-scale consequences in the installed production capacity outside the foreground system. Then: **Situation B**. If not: Situation A."

*(ILCD Handbook: General Guide for LCA (2010), p. 48)*

Additionally, regarding multifunctionality specifically: if no functionally equivalent alternative processes exist (or they are not operated to a sufficient extent), "the study is in fact a Situation B type study, as this implies large-scale consequences on other systems."

*(ILCD Handbook: General Guide for LCA (2010), p. 91)*


Question: When aggregating unit processes to LCI results, how should product and waste flows be handled if background data of sufficient quality is not available for them?

These flows shall remain in the aggregated inventory, making the data set a "partly terminated system," and the user must be explicitly informed in a prominent place that these parts still need to be completed or the gap considered in further use and interpretation.

When background data of sufficient quality is not available for product or waste flows during aggregation of unit processes to LCI results, those flows should be **left as unresolved (open) flows in the LCI result** rather than being omitted or arbitrarily estimated.

Specifically:

- **Product flows** that cannot be linked to a background process should be retained as **elementary-flow-like residuals** or listed as unresolved intermediate flows, clearly documented as such, so downstream users are aware the supply chain is incomplete.
- **Waste flows** that cannot be connected to a treatment process should similarly be **carried forward as unresolved waste flows**, not simply dropped, because dropping them would imply the waste disappears without environmental consequence.

The key principle is **transparency and completeness of documentation**: unresolved flows must be explicitly reported so that:
1. Users understand the incompleteness of the system boundary.
2. The missing data can be identified and filled in later if better background data become available.
3. No implicit assumption (zero impact, or arbitrary substitution) is silently introduced into the result.

This approach is consistent with guidance in standards such as **ISO 14044** and practical LCI database construction guidelines (e.g., ecoinvent documentation), which require that unlinked flows be flagged rather than silently discarded.

When aggregating unit processes to LCI results, if background data of sufficient quality is not available for product and waste flows, **these flows shall remain in the aggregated inventory**, making the data set a "partly terminated system." The user of such data shall be explicitly informed in a prominent place that these parts of the system need to be still completed or the gap be considered in further use and interpretation.

*(Source 1: European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 210)*

When aggregating unit processes to LCI results, if background data of sufficient quality is not available for certain product and waste flows, **these flows shall remain in the aggregated inventory** — i.e., making the data set a "partly terminated system." The user of such data shall be explicitly informed in a prominent place that these parts of the system need to be still completed, or that the gap be considered in the further use and interpretation of results.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 210)*


Question: When combining data sets from different sources, what reference elementary flows should be used to ensure compatible inventories and avoid multiple occurrences of the same flows in joint or aggregated inventories?

## Reference Elementary Flows for Compatible LCA Inventories

When combining datasets from different sources, you should use **a common, shared list of reference elementary flows** to ensure compatibility. The key recommendations are:

### Recommended Reference Flow Lists

1. **ILCD Elementary Flow List** (European Commission/JRC)
   - Widely used in European contexts
   - Used as basis for EF (Environmental Footprint) methods

2. **Federal LCA Commons Elementary Flow List (FEDEFL)**
   - Developed by US EPA
   - Used in US government LCA databases (USLCI, etc.)

3. **ecoinvent Elementary Flow List**
   - Proprietary but widely adopted
   - Used within the ecoinvent database ecosystem

### Key Principles to Avoid Duplicate Flows

- **Use unique identifiers (UUIDs)** for each elementary flow, not just names
- **Standardize naming conventions** (substance name, compartment, sub-compartment)
- **Map flows to a common reference list** before aggregation using flow mapping/correspondence tables (e.g., the GLAD flow mapping tool)
- **Agree on compartment definitions** (e.g., "emission to air, unspecified" vs. "emission to air, lower stratosphere")

### Practical Approach

Use **flow mapping tables** (correspondence files) to translate source-specific flows to the target reference list before combining datasets. Tools like **OpenLCA**, **SimaPro**, and the **GLAD project** provide mapping support.

The **ILCD format** and **JSON-LD** exchange formats facilitate this by embedding flow UUIDs, reducing ambiguity when merging inventories.

The **ILCD reference elementary flows** should be used wherever possible and relevant when combining data sets from different sources. This ensures compatible inventories and avoids multiple occurrences of the same flows in joint or aggregated inventories.

*(Source 1: European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 153)*

Based on the context, the **ILCD reference elementary flows** should be used wherever possible and relevant when combining data sets from different sources. This ensures compatible inventories and avoids multiple occurrences of the same flows in joint/aggregated inventories.

*(European Commission – JRC, ILCD Handbook: General Guide for LCA (2010), p. 153)*


Question: What environmental topic did Finnveden's 2008 editorial in the International Journal of Life Cycle Assessment address regarding electricity production?

It addressed electricity production in consequential assessments in a world with CO2 caps.

Finnveden's 2008 editorial in the International Journal of Life Cycle Assessment addressed the question of how to handle electricity in LCA, specifically the issue of which electricity values or factors to use when modeling electricity production and consumption — particularly the debate around using average versus marginal electricity data/emission factors in life cycle assessment studies.

The provided context does not contain information about a 2008 editorial by Finnveden in the International Journal of Life Cycle Assessment regarding electricity production. The sources only reference Finnveden's works from 1996–1999.

The provided context does not contain information about a 2008 editorial by Finnveden in the International Journal of Life Cycle Assessment regarding electricity production. The context only references Finnveden's works from 1996–1999 (Source 1, p.648), none of which is a 2008 editorial on electricity production.


Question: Why are accidents and accident-type leakages and spills excluded from the normal life cycle inventory, and what related emissions are nevertheless included?

They are excluded because they are fundamentally different in nature from the production- or operation-related normal and abnormal operating conditions that LCA relates to; however, fugitive emissions through sealings and other "engineered losses" are included in LCA.

## Exclusion of Accidents from LCI

### Why Accidents Are Excluded

Accidents and accident-type leakages/spills are excluded from the normal life cycle inventory for several methodological reasons:

1. **Stochastic vs. deterministic nature**: Accidents are probabilistic events with highly uncertain occurrence rates, making them fundamentally different from the continuous, predictable flows that characterize normal operations
2. **High variability**: The magnitude of emissions from accidents varies enormously and unpredictably between facilities, locations, and circumstances
3. **Comparability**: Including accident probabilities would make inventories difficult to compare across systems, as risk assessments depend on local conditions, safety management, and regulatory context
4. **Scope clarity**: LCI focuses on *normal operating conditions* — the routine, reproducible material and energy flows that can be measured or modeled with reasonable certainty
5. **Separate risk assessment domain**: Accident risks are addressed through dedicated **risk assessment** methodologies (e.g., quantitative risk assessment, HAZOP), which are considered a complementary but distinct tool from LCA

---

### Related Emissions That *Are* Included

Despite excluding accidents, the following **routine/normal losses** are included:

- **Diffuse/fugitive emissions** during normal operation (e.g., valve leaks, evaporation losses)
- **Routine maintenance-related releases**
- **Small, continuous leakages** that are an inherent part of normal process operation
- **Emissions during start-up and shut-down** of processes (where these are regular, predictable events)

These are included because they are **systematic, foreseeable, and quantifiable** as part of normal operations, even if not intentional.

Accidents and accident-type leakages and spills are excluded from the normal life cycle inventory because **they are fundamentally different in nature from the production or operation-related normal and abnormal operating conditions that LCA relates to**. Additionally, accident modelling necessarily requires dealing with frequencies and cause-effect chains to assign them to the causing unit processes, making them methodologically distinct from standard LCI approaches. Work on "Life Cycle Accident Assessment" remains under methodological development.

However, **fugitive emissions through sealings and other "engineered losses"** are nevertheless included in the LCA, as these are considered part of normal operating conditions rather than accidental events.

Furthermore, use-phase related impacts that products exert **via an emission to the ecosphere** (e.g., smoke emissions to the environment, wastewater discharge) are also included, even for products such as food, healthcare products, or tobacco — though the direct health impacts these products exert within the technosphere are not covered.

*(ILCD Handbook: General Guide for LCA, 2010, p. 95)*

Accidents and accident-type leakages and spills are excluded from the normal life cycle inventory because they are **fundamentally different in nature from the production or operation-related normal and abnormal operating conditions** that LCA relates to. Additionally, accident modelling necessarily requires dealing with frequencies and with cause-effect chains to assign them to the causing unit processes, making them methodologically distinct from standard LCI approaches. Work on this "Life Cycle Accident Assessment" is still under methodological development (ILCD Handbook, p.95).

Nevertheless, **fugitive emissions through sealings and other "engineered losses"** are still included in the LCA, as these are considered part of normal operating conditions rather than accidents (ILCD Handbook, p.95).

As further clarified on the same page: "LCA only accounts for impacts related to normal and abnormal operation of processes and products, but not covering e.g. impacts from accidents, spills, and similar." Use-phase related impacts that products exert **via an emission to the ecosphere** (e.g., smoke emissions to the environment, wastewater discharge) are however to be included (ILCD Handbook, p.95).