Question: How does the goal of Cradle to Cradle differ from that of Life Cycle Assessment?

C2C seeks to increase positive impacts, whereas LCA seeks to reduce negative impacts.

**Cradle to Cradle (C2C)** and **Life Cycle Assessment (LCA)** differ mainly in their **purpose**:

- **Cradle to Cradle** is a **design philosophy and certification approach**. Its goal is to create products and systems that are **inherently beneficial**, where materials stay in **closed loops** (either biological or technical cycles), waste is designed out, and products are made for positive impact.

- **Life Cycle Assessment** is an **analytical method**. Its goal is to **measure and compare environmental impacts** across a product’s life cycle—from raw material extraction to production, use, and end-of-life—so decision-makers can identify hotspots and reduce harm.

### In short
- **C2C asks:** *How can we design this product to be good by design?*
- **LCA asks:** *What environmental burdens does this product cause over its life cycle?*

So, **C2C is normative and innovation-oriented**, while **LCA is evaluative and impact-oriented**.

Cradle to Cradle aims at a positive, regenerative design agenda—imitating nature and transforming linear systems into circular ones—whereas Life Cycle Assessment focuses on assessing and reducing negative environmental impacts across the life cycle.

Cited support:
- “Cradle to Cradle® (C2C) is based upon the idea of imitating nature in the approach to sustainable product and system design” and arose as a reaction to the “cradle to grave” perspective that reinforced a linear model (Hauschild et al., *LCA: Theory and Practice*, Chap. 25, p.606).
- LCA is associated with “eco-efficiency,” while C2C is framed as an agenda of “positivism, growth and innovation” (Hauschild et al., *LCA: Theory and Practice*, Chap. 23, p.554).
- In the comparison table, LCA’s focus is “Not explicitly” on positive environmental impacts; “Reducing negative impacts is the focus,” while for C2C positive impacts are “Potentially” included (Hauschild et al., *LCA: Theory and Practice*, Chap. 25, p.619).

Cradle to Cradle aims at a design transformation inspired by nature and a circular economy, reacting against the linear “cradle to grave” model and its reliance on end-of-pipe solutions (Chap. 25, p.606). By contrast, Life Cycle Assessment focuses on assessing environmental impacts across the life cycle, with emphasis on reducing negative impacts; positive environmental impacts are “not explicitly” included in standard LCA (Chap. 25, p.619).


Question: ISO 14040 covers critical review as part of its requirements. Given that critical review also addresses Life Cycle Inventory considerations, what standard would a practitioner need to consult to ensure both their critical review process and Life Cycle Inventory analysis meet established international guidelines?

A practitioner would need to consult ISO 14040 (Environmental Management – Life Cycle Assessment – Principles and Framework). The passages establish that ISO 14040 covers requirements such as critical review, and that critical review is one of the applicable requirements for LCA studies — alongside data quality, collection, calculation, and allocation — which are all part of the broader LCA process that includes the Life Cycle Inventory. Therefore, ISO 14040 serves as the overarching standard connecting the critical review process to Life Cycle Inventory requirements.

A practitioner should consult:

- **ISO 14040** for the **critical review** framework and overall LCA principles
- **ISO 14044** for the detailed requirements on **Life Cycle Inventory (LCI)**, impact assessment, interpretation, and the practical conduct of critical review

So, to ensure both the **critical review process** and **LCI analysis** meet international guidelines, the key standard is **ISO 14044**, used together with **ISO 14040**.

A practitioner should consult both:

- **ISO 14040 / ISO 14044** for the **critical review** requirements, since critical review is defined as a process linked to ISO 14044 and based on the ISO 14040/14044 standards (**Hauschild et al., Ch. 13, p.335; p.339**).
- **ISO 14041** for **Life Cycle Inventory (LCI) analysis**, since ISO 14041 specifies the LCI operational steps, including data collection, validation, allocation, aggregation, and system boundary refinement (**Guinée et al., p.443**).

So, to cover both aspects under established international guidelines, the relevant standards are **ISO 14040/14044 for critical review and ISO 14041 for LCI analysis** (**Hauschild et al., Ch. 13, pp.335, 339; Guinée et al., p.443**).

A practitioner would need to consult both:

- **ISO 14040/14044** for the **critical review** requirements, since critical review is “intrinsically linked to **ISO 14044 (2006a)**” and is based on the international standards **ISO 14040:2006, ISO 14044:2006 and ISO TS 14071:2014** (Hauschild et al., **Chapter 13 Critical Review, pp. 335, 339**).
- **ISO 14041** for the **Life Cycle Inventory (LCI) analysis**, since “in **ISO 14041 (1998E)** the Inventory analysis phase is broken down into” the operational LCI steps (Guinée et al., **Handbook on LCA, p. 443**).

So, to cover both areas, the relevant standards are **ISO 14044 (with ISO 14040 as the overarching framework) and ISO 14041** (Hauschild et al., **Chapter 13, pp. 335, 339**; Guinée et al., **p. 443**).


Question: What are the three main target audiences for increasing the demand for ecolabelled products?

Consumers; public procurement; and procurement in private companies and organisations.

The three main target audiences are typically:

1. **Consumers / households** – to drive everyday purchasing of ecolabelled products.
2. **Businesses / professional buyers** – including retailers, companies, and supply-chain purchasers.
3. **Public authorities / institutional procurers** – governments, municipalities, schools, hospitals, etc., through green public procurement.

These groups are targeted because they strongly influence market demand from individual, commercial, and public purchasing channels.

The three main target audiences are:
- Consumers
- Public procurement
- Procurement in private companies and organisations

Chapter 24, p.591 (Hauschild et al., *LCA: Theory and Practice*)

The three main target audiences are:

- Consumers
- Public procurement
- Procurement in private companies and organisations

(Hauschild et al., *LCA: Theory and Practice*, Chapter 24 “Environmental Labels and Declarations”, p. 591)


Question: What is the purpose of increasing the demand for ecolabelled products in addition to targeting suppliers?

To create a pull effect in the market, yielding environmental benefits by changing consumption toward more sustainable products and services.

Increasing demand for ecolabelled products complements supplier-focused efforts by creating market pull.

Main purposes:
- **Reward better suppliers:** If buyers prefer ecolabelled products, suppliers have a stronger incentive to meet ecolabel criteria.
- **Scale environmental impact:** More demand means more ecolabelled products sold, leading to broader reductions in environmental burdens.
- **Make supplier changes commercially viable:** Suppliers are more likely to invest in certification or improved practices when they see clear customer demand.
- **Transform the market:** Demand-side pressure helps move ecolabels from niche products to mainstream options.
- **Support continuous improvement:** Strong demand can encourage tighter standards and more innovation over time.

So, targeting suppliers improves availability, while increasing demand ensures those improved products are actually chosen and sustained in the market.

To create a “pull effect” in the market and thereby increase demand for more sustainable products and services, yielding environmental benefits from shifting consumption. (Chapter 24, p.591)

The purpose is “to create a pull effect in the market” and thereby “yield environmental benefits from changing the consumption to more sustainable products and services,” rather than only influencing suppliers. This is aimed especially at consumers, public procurement, and private-company procurement. (Hauschild et al., *LCA: Theory and Practice*, Ch. 24, p. 591)


Question: What must a designer carefully choose to obey the three key principles and plan for materials moving through multiple life cycles or cascades?

To follow those principles, a designer must carefully choose **materials and product architecture**—specifically:

- **Safe, non-toxic materials**
- **Compatible materials that can stay in clean cycles**
- **How components are joined, separated, repaired, reused, remanufactured, and recycled**

In other words, the designer needs to select **materials and assembly methods** so products can move through **multiple life cycles or cascades** effectively.

The designer must carefully choose the material composition of a product to obey the three key principles and plan for the fate of the materials through multiple life cycles (“cascades”).
— Hauschild et al., *LCA: Theory and Practice*, Chapter 25 “Cradle to Cradle and LCA,” p.619

The designer must carefully choose **the material composition of a product** to obey the three key principles and plan for the fate of the materials through multiple life cycles (“cascades”) (Hauschild et al., *LCA: Theory and Practice*, Chap. 25, p. 619).


Question: Why has it been difficult to realise the potential of public procurement in the European market until recently?

Because EU regulation did not allow public authorities to set ecolabels as a requirement for procurement in tenders.

It has been difficult because, although public procurement is economically huge in Europe, it was long treated mainly as an **administrative and legal function**, not a **strategic market-shaping tool**.

Key reasons include:

- **Fragmentation of demand**: public purchasing is spread across thousands of authorities, sectors, and countries, so buying power was not coordinated.
- **Focus on lowest upfront price**: procurement decisions often prioritized short-term cost over innovation, quality, lifecycle costs, or sustainability.
- **Complex EU and national rules**: procedures were often seen as rigid and risk-averse, discouraging experimentation and strategic use.
- **Limited professionalization**: many procurers lacked the skills, data, and tools to use procurement strategically.
- **Weak cross-border competition**: national practices, language, standards, and legal differences limited the integration of a true European procurement market.
- **Policy misalignment**: procurement was not always well connected to broader goals like industrial policy, innovation, green transition, or SME support.

Only more recently has procurement been more widely recognized as a lever for **innovation, sustainability, and market transformation**, especially through reforms encouraging lifecycle thinking, green public procurement, and strategic purchasing.

It has been difficult because public procurement’s potential was constrained by barriers to sustainable consumption and production that had to be identified and overcome only through later EU action plans and related policy instruments promoting coherence across policy areas and addressing gaps. This is described in *Hauschild et al., LCA: Theory and Practice*, Chapter 18, p.443.

It has been difficult because the environmental potential of public procurement “was not in itself sufficient to trigger a market for greener products and services,” so its use in Europe required broader policy support to identify and overcome barriers through SCP/SIP action plans and related instruments such as Green Public Purchasing. (Hauschild et al., *Life Cycle Thinking and the Use of LCA in Policies Around the World*, ch. 18, p. 443)


Question: In an LCA, which step aims to cover a comprehensive list of environmental issues?

The LCIA (life cycle impact assessment) step.

In an LCA, the step that aims to cover a comprehensive list of environmental issues is the **Life Cycle Impact Assessment (LCIA)** phase, specifically the **selection of impact categories**.

This is where the study identifies and includes relevant environmental issues such as:

- climate change
- ozone depletion
- acidification
- eutrophication
- human toxicity
- ecotoxicity
- resource depletion

More broadly, this happens within the **goal and scope definition** and is then operationalized in the **LCIA**.

The LCIA step aims to cover a comprehensive list of environmental issues.
Cited source: Hauschild et al., *LCA: Theory and Practice*, Ch. 25 “Cradle to Cradle and LCA,” p. 619.

The life cycle impact assessment (LCIA) step aims to cover a comprehensive list of environmental issues. (Hauschild et al., *LCA: Theory and Practice*, Chap. 25, p. 619)


Question: Why does the cradle-to-cradle approach not explicitly cover any environmental issues?

Because no negative impacts are assumed to happen when the three key principles are followed.

Because **“cradle-to-cradle” is mainly a design philosophy, not a full environmental impact assessment method**.

Key reason:
- It focuses on **keeping materials in closed loops** so products become “nutrients” for new cycles, rather than waste.
- But it does **not explicitly evaluate environmental impact categories** such as:
  - climate change
  - acidification
  - eutrophication
  - toxicity
  - water use
  - resource depletion

So a product can be “cradle-to-cradle” in the sense of recyclability or circularity, while still causing significant impacts in production, transport, energy use, or emissions.

In short:
- **Cradle-to-cradle asks:** can materials circulate endlessly?
- **LCA asks:** what environmental burdens occur across the life cycle?

That is why cradle-to-cradle does not explicitly cover environmental issues: **its emphasis is circular material design, not quantified multi-impact environmental assessment.**

Because in LCA the included environmental issues are determined by the goal and scope definition, whereas cradle-to-cradle does not explicitly focus on environmental issues as such; its focus is on reducing negative impacts, and positive impacts are only potentially considered. (Hauschild et al., *LCA: Theory and Practice*, Chap. 25, p. 619)

Because Cradle to Cradle focuses on “positive environmental impacts,” whereas LCA/LCIA explicitly aims to cover a comprehensive list of environmental issues and, in contrast, “reducing negative impacts is the focus.” In the comparison table, Cradle to Cradle is marked as covering positive impacts, while for LCA it says “Not explicitly” under positive impacts and notes that reducing negative impacts is the focus, which explains why Cradle to Cradle does not explicitly cover environmental issues in the LCA sense (Hauschild et al., *LCA: Theory and Practice*, Ch. 25, p. 619).


Question: What types of generation and conditioning systems are included within the spectrum of energy systems described in the chapter?

Electricity generation systems, heat generation systems, and cooling systems.

The chapter’s “spectrum of energy systems” generally includes both **energy generation** and **conditioning/conversion** systems, such as:

- **Electricity generation systems**
  - Fossil-fuel plants
  - Nuclear power plants
  - Renewable systems like wind, solar, hydro, geothermal, and biomass

- **Thermal generation systems**
  - Boilers
  - Furnaces
  - Combined heat and power (CHP/cogeneration)

- **Conditioning systems**
  - Heating systems
  - Ventilation and air-conditioning (HVAC)
  - Refrigeration and cooling systems
  - Heat pumps
  - Energy conversion and distribution equipment

So, the spectrum spans from **primary energy generation** to the **systems that condition energy for end use**, especially for heating, cooling, and power delivery.

The chapter states that energy systems “can span a wide spectrum of electricity and heat generation systems and cooling systems.” (Hauschild et al., *LCA: Theory and Practice*, Chapter 26, p.633)

The chapter states that energy systems “can span a wide spectrum of electricity and heat generation systems and cooling systems” (Hauschild et al., Chapter 26, p. 633).


Question: What two modelling approaches can be used to address the challenge of an intermittent electricity source?

Modelling the intermittent source with a storage system, or adding a compensating source for whenever the intermittent source cannot supply electricity.

Two common LCA modelling approaches for handling **intermittent electricity sources** are:

1. **Average/annual mix modelling**
   Model the electricity using an average grid mix or average output over a period (for example, annual or monthly averages). This is simpler but can miss temporal variability.

2. **Time-dependent / temporal marginal modelling**
   Model electricity with time resolution, linking generation and demand by hour or shorter intervals and often using marginal suppliers. This better captures intermittency and storage/backup effects.

If you want, I can also explain how these relate to attributional vs consequential LCA.

Two approaches are mentioned:

1. Modelling the intermittent source with a storage system.
2. Adding a compensating source whenever the intermittent source cannot supply electricity.

Source: Hauschild et al., LCA: Theory and Practice, Chapter 26, p.652.

Two approaches are mentioned:

1. **Model the intermittent source with a storage system**.
2. **Add a compensating source whenever the intermittent source cannot supply electricity**.

Source: *Hauschild et al., LCA: Theory and Practice*, Chap. 26, p. 652.


Question: What standard defines Environmental Management Systems, and what broad thinking approach related to product assessment does that same standard cover?

According to the passages, ISO 14001 is the standard that defines Environmental Management Systems (its full title being "Environmental management systems – Requirements with guidance for use"). ISO 14001 also covers Life Cycle Thinking, thereby connecting the concept of Environmental Management Systems to the broader approach of considering environmental impacts across a product's entire life cycle.

The standard is **ISO 14001**, which defines **Environmental Management Systems (EMS)**.

That same standard also promotes a **life cycle perspective**—broad thinking that considers environmental impacts across a product’s stages, from raw material extraction through production, use, and end-of-life.

Environmental Management Systems are defined by **ISO 14001**. In its 2015 revision, that same standard also requires **a life cycle view/life cycle thinking on the produced products**, beyond just a production focus.
**Citation:** Hauschild et al., *LCA: Theory and Practice*, **Chap. 22, p. 525**.

Environmental Management Systems are defined by **ISO 14001**: “environmental management systems (EMS), which usually follow ISO 14001 or EMAS” (Hauschild et al., **Chapter 20, p. 483**).

That same standard, in its 2015 revision, also requires a **life cycle view/perspective on products**: “ISO 14001 … now requires a view on life cycles of the produced products as well” (Hauschild et al., **Chapter 22, p. 525**).


Question: What two categories of published LCA studies applied to electricity and heat systems were identified?

(i) studies assessing specific energy technologies, sources, or systems at a power plant or sub-power plant level, and (ii) studies, typically at meso- and large-scale, assessing energy systems in a context perspective.

Two categories were identified:

1. **Attributional LCA (ALCA)** studies of electricity and heat systems
2. **Consequential LCA (CLCA)** studies of electricity and heat systems

Two categories were identified:

1. Studies assessing specific energy technologies/sources/systems at a power plant or sub-power plant level.
2. Studies, typically at meso- and large-scale, assessing energy systems in a context perspective.

(Hauschild et al., *LCA: Theory and Practice*, Chapter 26 “LCA of Energy Systems”, p.652)

Two categories were identified:

1. “studies assessing specific energy technologies/sources/systems at a power plant or sub-power plant level,” and
2. “studies, typically at meso- and large-scale, assessing energy systems in a context perspective.”

(Hauschild et al., *LCA: Theory and Practice*, Chapter 26 “LCA of Energy Systems,” p. 652)


Question: Comparing electricity supply systems that match which two types of demand presents similar modelling challenges?

Systems matching base-load electricity demand and those matching peak-load electricity demand.

Comparing electricity supply systems that are designed to match **peak demand** and **variable/intermittent demand** presents similar modelling challenges.

This is because both require careful treatment of:
- time-dependent supply and demand,
- capacity adequacy,
- storage or backup generation,
- and marginal vs. average electricity mixes.

Comparing electricity supply systems matching base-load electricity demand and those matching peak-load electricity demand presents similar modelling challenges.
Chapter 26, p.652.

Similar modelling challenges arise when comparing electricity supply systems matching **base-load electricity demand** versus **peak-load electricity demand** (Hauschild et al., *LCA: Theory and Practice*, Ch. 26, p.652).


Question: Approximately how many LCA studies have focused on energy systems over the past two decades, and what was their aim?

More than 1000 LCA studies, with the aim to identify and reduce the impacts of energy systems.

Roughly **a few thousand LCA studies** have examined **energy systems** over the past 20 years. Their main aim has been to **evaluate the environmental impacts of energy technologies and pathways across their full life cycle**—from raw material extraction and construction to operation and end-of-life—so they can **compare options like fossil, nuclear, and renewable systems and support better energy and climate decision-making**.

Approximately 674 scientific articles on LCA of energy systems had been identified up to 2015. Their aim was generally to assess energy supply systems—mainly electricity and heat production systems and transportation fuels—either at the technology level for eco-design, environmental performance reporting, and benchmarking, or at broader system level for policy analysis and decision-making at urban, national, or regional scales. (Chapter 26, pp. 634, 636)

Approximately **674 scientific articles published up to 2015** were identified for LCA studies on **energy systems and technologies**, showing strong growth over the past two decades. These studies focused on **energy supply systems**, mainly **electricity and heat production systems and fuels for transportation** (Hauschild et al., *LCA: Theory and Practice*, ch. 26, p. 634).

Their aims were mainly of two kinds:
1. **Specific technology/system studies** at power plant or component level, aimed at **weak-point analysis for eco-design, reporting/documentation of environmental performance of new technologies, and benchmarking against other technologies**.
2. **Context-oriented studies** at meso- to large scale, aimed at **policy analysis and decision-/policy-making** at **urban, national, or regional scales** (Hauschild et al., *LCA: Theory and Practice*, ch. 26, p. 636).


Question: Why are electric vehicles considered a key technology for reducing the environmental impact of the mobility sector?

Because they can radically decrease greenhouse gas production by avoiding the generation of tailpipe emissions.

Electric vehicles are considered key because they can cut the mobility sector’s environmental impact across several major categories, especially when paired with cleaner electricity.

## Main reasons

- **No tailpipe emissions**
  EVs do not emit exhaust while driving, so they avoid direct emissions of:
  - CO2
  - NOx
  - particulate matter
  - other air pollutants
  This improves **urban air quality** and reduces health impacts.

- **Higher energy efficiency**
  Electric drivetrains convert energy to motion much more efficiently than internal combustion engines.
  That means:
  - less energy used per kilometer
  - lower total environmental burdens from operation

- **Lower life-cycle greenhouse gas emissions**
  Even though EVs often have **higher manufacturing impacts**, especially from battery production, they usually achieve **lower total life-cycle CO2 emissions** than gasoline or diesel cars because the use phase is much cleaner.

- **Can be decarbonized over time**
  The climate impact of EVs depends strongly on the **electricity mix**. As power grids add more renewables, the same EV becomes cleaner over its lifetime, unlike conventional vehicles that remain tied to fossil fuels.

- **Supports integration with renewable energy**
  EVs can help wider energy-system decarbonization through:
  - smart charging
  - off-peak charging
  - potential vehicle-to-grid services

## Important caveats

EVs are not impact-free. Key concerns include:
- battery material extraction and processing
- manufacturing emissions
- electricity source
- vehicle size and weight
- tire and brake particle emissions

So, from an **LCA perspective**, EVs are important because they typically **shift impacts away from fossil fuel combustion in use** and offer strong potential for **substantial life-cycle emission reductions**, especially in low-carbon electricity systems.

Electric vehicles are considered a key technology because they can radically reduce greenhouse gas emissions by avoiding tailpipe emissions from private transportation, which is increasingly responsible for a significant share of GHG emissions. However, their overall benefit depends on factors such as battery production and the energy source used during operation. (Hauschild et al., *LCA: Theory and Practice*, Chapter 27, p. 669–670)

Electric vehicles are considered a key technology because they can “decrease the production of greenhouse gases radically by avoiding the generation of tailpipe emissions,” helping reduce the environmental impact of private transportation, which is responsible for a significant share of GHG emissions. However, the chapter also notes that this benefit must be assessed over the full life cycle because battery production and additional material requirements can shift impacts to other stages or impact categories (Chapter 27, p.669; p.670).


Question: What share of the total CO2-equivalent emissions of a vehicle's manufacturing stage is attributed to the production of the battery system?

Around 40–50% of the total CO2-eq. emissions of the vehicle's manufacturing stage.

A common rule of thumb for battery electric vehicles is that the **battery system accounts for roughly 25–50% of the manufacturing-stage CO₂e emissions**.

A more typical central estimate is often around **one-third to nearly one-half**, depending on:

- **Battery size** (kWh)
- **Cell chemistry** and material sourcing
- **Electricity mix** used in battery and vehicle production
- **How the system boundary is defined** in the LCA

So, if you need a single concise answer: **about 30–40% of total vehicle manufacturing CO₂e is often attributed to the battery system**, though values outside that range are also reported.

Around 40–50% of the total CO2-eq. emissions of the vehicle’s manufacturing stage are attributed to the battery system production. (Hauschild et al., *LCA: Theory and Practice*, Chapter 27 “LCA of Electromobility,” p.669)

The battery system production is “responsible for around 40–50% of the total CO2-eq. emissions of the vehicle’s manufacturing stage” (Hauschild et al., Chapter 27, p. 669).


Question: In the Life Cycle Impact Assessment (LCIA) phase, which step must be completed immediately before the results can move forward to Life Cycle Interpretation, and what step must be completed before that one?

According to the passages, Characterisation must be completed first, followed by Normalisation, and only after Normalisation is completed can the results proceed to the Interpretation phase (Life Cycle Interpretation). In other words, Characterisation precedes Normalisation, and Normalisation precedes Life Cycle Interpretation.

Immediately before moving to **Life Cycle Interpretation**, the LCIA results must be in the **normalization** step.

The step completed just before **normalization** is **weighting**.

So the sequence is:

**Weighting → Normalization → Life Cycle Interpretation**

Immediately before results move forward to Life Cycle Interpretation, the LCIA must have completed **characterization**. Before that, it must have completed **classification**.

This is indicated by the standards clarification that **“after characterization and before further optional elements”** the results are represented as sets of impact category indicator results and related data, i.e. the form available for subsequent interpretation (Finkbeiner et al., *The New International Standards for LCA: ISO 14040 & 14044*, p.11). The prior required LCIA step is classification, as the ILCD guidance notes the need to ensure **“classification and characterisation of all elementary flows”** are done (European Commission – JRC, *ILCD Handbook*, Chapter 8, p.281).

Citations:
- Finkbeiner et al. (2006), p.11
- European Commission – JRC, *ILCD Handbook*, Chapter 8, p.281

Immediately before results can move forward to Life Cycle Interpretation, **characterisation** must be completed. Before that, **classification** must be completed.

This is reflected in the standards clarification that **“after characterization and before further optional elements”** the LCIA results are represented as impact category indicator results, i.e. ready to proceed onward, and in LCIA practice where classification and characterisation are the core preceding steps of impact assessment (Finkbeiner et al. 2006, p.11; Hauschild et al., Chapter 10, p.169).


Question: In a Life Cycle Inventory, what greenhouse gas is released as a result of soil organic carbon changes from land use and transformation, and from which broader category of processes is this same gas also emitted?

Soil organic carbon (SOC) changes from land use and land transformation emit carbon dioxide (CO₂), as the ILCD Handbook requires the use of IPCC CO₂ emission factors to model CO₂ release from or binding in SOC. That same gas — carbon dioxide — is also emitted by energy conversion processes, thereby linking soil organic carbon changes to energy conversion processes through their shared emission of CO₂.

The greenhouse gas is **carbon dioxide (CO₂)**.

In an LCI, CO₂ is released due to **soil organic carbon changes from land use and land transformation**, and the same gas is also emitted from the broader category of **combustion processes** (for example, burning fossil fuels or biomass).

The greenhouse gas released from soil organic carbon changes due to land use and land transformation is **CO2 (carbon dioxide)**: “The differences in soil organic carbon is mostly emitted as CO2” ([ILCD Handbook, p.234](Source 3)).

This same gas is also emitted from the broader category of **energy conversion during manufacturing, transport of goods and end-of-life treatment processes** ([Hauschild et al., LCA: Theory and Practice, p.791](Source 8)).

The greenhouse gas is **CO2 (carbon dioxide)**. The ILCD Handbook states that differences in soil organic carbon from land use and land transformation are “**mostly emitted as CO2**” (European Commission – JRC, *ILCD Handbook: General Guide for LCA*, p.234).

The same gas is also emitted from the broader category of **“land use and transformation related CO2 emissions from biomass and litter”** (Hauschild et al., *LCA: Theory and Practice*, Chapter 37 “LCA Cookbook”, p.1030).


Question: What three categories of impacts have energy systems been demonstrated to seriously affect?

Human health, ecosystems, and natural resources.

Energy systems have been shown to seriously affect three broad impact categories:

1. **Human health**
   via air pollution, toxic emissions, occupational risks, and climate-related health effects.

2. **Ecosystem quality / ecological health**
   through land use, habitat disruption, acidification, eutrophication, and biodiversity loss.

3. **Resource depletion / resource availability**
   by consuming nonrenewable fuels, minerals, water, and other natural resources.

These are also the classic top-level damage categories used in many life cycle assessment frameworks.

Energy systems have been demonstrated to cause serious impacts on:
- human health
- ecosystems
- natural resources

(Hauschild et al., *LCA: Theory and Practice*, Chapter 26 “LCA of Energy Systems,” p.633)

Energy systems have been demonstrated to cause serious impacts on:

- human health
- ecosystems
- natural resources

(Hauschild et al., Chapter 26, p.633)


Question: What does the acronym GREET stand for in the context of transportation modelling?

Greenhouse gases, Regulated Emissions and Energy use in Transportation model.

In transportation modelling, **GREET** stands for **Greenhouse gases, Regulated Emissions, and Energy use in Technologies**.

It is a lifecycle assessment model developed by **Argonne National Laboratory** to evaluate the energy use and emissions of fuels and vehicle technologies.

The provided context does not state what GREET stands for.

GREET stands for **“Greenhouse gases, Regulated Emissions and Energy use in Transportation model”**.
(Hauschild et al., *LCA: Theory and Practice*, Ch. 27 “LCA of Electromobility”, p. 681)


Question: Which materials does the production of electric vehicle components require that could shift environmental problems to other life cycle stages or areas of impact?

Metals like copper and aluminium for the battery system, as well as rare earth metals for the production of electric motors.

Electric vehicle components—especially the **battery**, **electric motor**, **power electronics**, and **lightweight body parts**—often require materials whose production can shift environmental burdens from vehicle use to **raw material extraction and manufacturing**, or from **climate change** to other impact categories like **toxicity, water scarcity, land use, and resource depletion**.

Key materials include:

- **Lithium**
  Used in Li-ion batteries. Extraction can cause **high water use**, especially in arid regions, and contributes to **resource depletion**.

- **Cobalt**
  Used in many cathode chemistries. Associated with **human toxicity**, **ecotoxicity**, and major **social/supply-chain concerns** from mining.

- **Nickel**
  Important in high-energy batteries. Its production is **energy-intensive** and linked to **air pollution**, **acidification**, and **toxicity**.

- **Manganese and graphite**
  Also used in batteries. Graphite production can involve significant **energy use** and emissions; mining can add **ecological impacts**.

- **Copper**
  Needed in large amounts for motors, wiring, and charging systems. Mining and refining can increase **resource depletion**, **acidification**, and **ecotoxicity**.

- **Rare earth elements** such as **neodymium, dysprosium, and praseodymium**
  Used in permanent magnets in electric motors. Their extraction and processing can cause substantial **land disturbance**, **toxic waste**, and **human/ecotoxicity** impacts.

- **Aluminum**
  Used for lightweighting vehicle structures. Primary aluminum production is very **electricity-intensive**, so it can shift impacts to the **manufacturing stage** unless low-carbon electricity or recycled aluminum is used.

- **Steel and specialty alloys**
  Still important in EVs, with impacts from **energy use** and **mining**.

- **Semiconductor materials**
  Such as **silicon, gallium, and other specialty metals** in power electronics. These can involve **high-purity processing** with notable manufacturing impacts.

So, in LCA terms, EVs often reduce **tailpipe emissions** but may increase burdens in **upstream material production**, shifting impacts toward **mining, processing, electricity use in manufacturing, toxicity, and water-related categories**.

The production of EV components can require additional amounts of metals such as copper and aluminium for the battery system, as well as rare earth metals for the production of electric motors, which may shift environmental problems to other life cycle stages or impact areas (Chapter 27, p. 669).

The production of EV components can require additional **metals like copper and aluminium for the battery system**, as well as **rare earth metals for the production of electric motors**; these may shift environmental problems to other life cycle stages or areas of impact. (Hauschild et al., Chapter 27, p. 669)


Question: What type of content does a Non-assertive comparative LCA study ultimately address, given its place in the broader classification of LCA deliverables?

A Non-assertive comparative LCA study is a variant of a Comparative Life Cycle Assessment study ("Comparative LCA study"), and a Comparative LCA study — by its very nature — covers the comparison of LCA results for different products. Therefore, a Non-assertive comparative LCA study ultimately addresses the comparison of LCA results for different products, but does so without explicitly concluding the superiority, inferiority, or equality of the compared alternatives (unlike a Comparative assertion LCA study).

A non-assertive comparative LCA study ultimately addresses **environmental product information**, not a public comparative claim.

In the broader classification of LCA deliverables, it sits under **comparative studies**, but unlike an **assertive comparative assertion** (used to publicly claim one product is better than another), a **non-assertive** comparative study is typically for **internal decision support, development, or business-to-business use**. So its content is comparative environmental assessment information, but **not intended as a public superiority claim**.

A **Non-assertive comparative LCA study** ultimately addresses **the comparison of alternatives**, but **without explicitly concluding superiority, inferiority, or equality**. In the broader classification of LCA deliverables, it is listed as a variant of a **Comparative LCA study**, alongside **Comparative assertion LCA studies**, where such explicit conclusions are made. The ILCD further states that “comparative study” covers **both assertive and non-assertive studies that compare alternatives**.
**Citations:** ILCD Handbook, Ch. 6, p.55; Ch. 6.10.2, p.140.

A non-assertive comparative LCA study is a type of **Comparative Life Cycle Assessment study**, which in the ILCD classification is one of the **deliverables of an LCI/LCA study**; as such, it ultimately addresses **the comparison of alternatives without explicitly concluding superiority, inferiority, or equality**. This sits within the broader classification of LCA deliverables alongside other study outputs such as detailed LCI models. (European Commission – JRC, *ILCD Handbook: General Guide for LCA* (2010), ch. 6, p.55)


Question: What perspective was the GREET model originally created to evaluate vehicles on, and what additional model does its current version include?

It was originally created to evaluate vehicles on a well-to-wheel (WTW) perspective, and its current version includes a vehicle-cycle model containing information about the production and end-of-life stages of automotive components, including alternative drive trains.

The GREET model was originally created to evaluate vehicles from a **full fuel-cycle (well-to-wheel)** perspective.

Its current version also includes a **vehicle-cycle model**, allowing analysis of **vehicle production, materials, and end-of-life impacts** in addition to fuel use.

The GREET model was originally created to evaluate vehicles from a **WTW (well-to-wheels) perspective**, and its current version includes a **vehicle-cycle model** covering production and end-of-life stages of automotive components, including alternative drivetrains.
**(Hauschild et al., *LCA: Theory and Practice*, Chapter 27, p.681)**

The GREET model was originally created to evaluate vehicles from a **WTW (Well-to-Wheel) perspective**. Its current version includes a **vehicle-cycle model**, covering production and end-of-life stages of automotive components, including alternative drivetrains.
(Hauschild et al., *LCA: Theory and Practice*, Chapter 27, p. 681)


Question: In a life cycle assessment study, waste flows generated at the end of a product's use stage must be inventoried on the output side of the relevant processes. What broader methodological component of an LCA are these waste flow modelling requirements a part of, and what overarching phase of the study does that component itself fall under?

Waste flows — such as end-of-life products generated during the use stage — must be modelled following material flow logic and inventoried on the output side of the processes where they are generated. This waste flow modelling is carried out as part of the LCI (Life Cycle Inventory) model. The LCI modelling, in turn, must meet the requirements set by the goal and scope definition of the study, meaning that the entire chain — from how waste flows are handled up to the consistency of secondary data sets selected — is governed by and falls under the scope definition phase of the LCA.

They are part of the **modelling of waste management and end-of-life processes within the life cycle inventory (LCI) modelling framework**.

That component itself falls under the broader **Life Cycle Inventory (LCI) phase** of the LCA study.

So, in short:

- **Broader methodological component:** waste/end-of-life flow modelling in the **LCI model**
- **Overarching LCA phase:** **Life Cycle Inventory (LCI)**

These waste flow modelling requirements are part of the **Life Cycle Inventory (LCI) analysis**, specifically the component on **collecting data, modelling the system, and calculating results**, including **modelling waste treatment** and identifying **product and waste flows** on process inputs/outputs (ILCD Handbook, **Chapter 7, p.244**; also p.163).

That component itself falls under the broader **Inventory analysis phase** of the LCA study, which is the second phase concerned with collecting the data necessary for the study and compiling the inventory of input/output data (Guinée et al., **Part 3, Chapter 3, p.477**).

These waste flow modelling requirements are part of the **Life Cycle Inventory (LCI) analysis**, specifically the component on **collecting data, modelling the system, and calculating results**. The ILCD Handbook states that inventory work includes **“Waste flows … that need to be linked with waste management processes”** and gives the requirement that waste flows be modelled on the output side where they are generated (European Commission – JRC, ILCD Handbook, p.153; p.244).

That component itself falls under the broader **Inventory analysis phase**, which Guinée et al. identify as **“the second phase of an LCA”** (Guinée et al., Handbook on LCA, p.477).

**Citations:** ILCD Handbook, p.153 and p.244; Guinée et al., p.477.


Question: In the structured framework of Life Cycle Assessment, under what broader data quality dimension does time-related representativeness fall, and what overarching methodology does that dimension belong to?

Time-related representativeness is one of three dimensions — alongside technological and geographical representativeness — that together constitute the Representativeness of LCI Data, which addresses how well the process data collected in the Life Cycle Inventory reflects the product system it is intended to represent. This representativeness of LCI data is itself a component of the broader Life Cycle Assessment framework, as evidenced by its dedicated treatment within the LCA guidance structure (section 6.8 of the ILCD Handbook).

Time-related representativeness falls under the broader data quality dimension of **representativeness**.

That dimension belongs to the overarching **Life Cycle Inventory (LCI) data quality assessment / data quality indicators (DQI) methodology** used within LCA.

Time-related representativeness falls under the broader data quality dimension of **representativeness**. In the ILCD framework, LCI data quality is structured into “**representativeness (composed of technological, geographical, and time-related)**, completeness, precision/uncertainty, and methodological appropriateness and consistency” within the **Life Cycle Inventory (LCI) data quality** methodology of LCA.
— ILCD Handbook, **Section 6.8.1, p.122** [Source 2]

Time-related representativeness falls under **representativeness**, which is a key component of **LCI data quality**. The ILCD Handbook states: “LCI data quality can be structured by representativeness (composed of technological, geographical, and time-related)…” (European Commission – JRC, *ILCD Handbook: General Guide for LCA*, Sect. 6.8.1, p.122).


Question: How is the built environment defined in relation to individual buildings?

The built environment is a collection of autonomous buildings along with the infrastructure and human activity between those buildings.

The **built environment** is broader than any single building. It refers to the **human-made physical surroundings** where people live, work, and move, including:

- **Individual buildings**
- **Groups of buildings**
- **Infrastructure** such as roads, bridges, utilities, and transit systems
- **Public spaces** like parks, plazas, and streetscapes

So, **a building is one component of the built environment**, while the built environment is the **larger system or context** made up of buildings plus the spaces and infrastructure around them.

The built environment is defined as “a collection of autonomous buildings along with the infrastructure and human activity between those buildings,” whereas an individual building is “an independent structure that provides shelter from the elements to facilitate one or multiple human activities.” (Hauschild et al., *LCA: Theory and Practice*, Chapter 28, pp. 695–696)

The built environment is defined as broader than an individual building: an individual building is “an independent structure that provides shelter,” whereas the built environment is “an umbrella term for the buildings, infrastructure and the human activity between buildings.” It is also described as “a collection of autonomous buildings along with the infrastructure and human activity between those buildings.” (Hauschild et al., Chapter 28, pp. 695–696)


Question: What is a common practice for modelling life cycle inventories of electric vehicles, and which conventional vehicle's inventory has often been adapted for research?

A common practice is to adapt or convert data from conventional vehicles, such as replacing the fuel tank with a battery and combustion and exhaust systems with charging and power electronic systems; the LCI of the VW Golf has often been adapted and extrapolated for research purposes.

A common practice is to model an electric vehicle’s life cycle inventory by adapting an existing conventional vehicle inventory and replacing or modifying the powertrain-related components.

In research, the inventory of a conventional internal combustion vehicle—especially a **Volkswagen Golf** (often based on datasets like the Golf A4/A5)—has frequently been adapted for this purpose.

A common practice is to adapt or convert data from conventional vehicles, for example by replacing the fuel tank with a battery and the combustion and exhaust systems with charging and power electronic systems. The life cycle inventory of the VW Golf has often been adapted and extrapolated for research purposes. (Chapter 27, p.681)

A common practice is to adapt or convert data from conventional vehicles when modelling EV life cycle inventories, for example by replacing the fuel tank with a battery and the combustion/exhaust systems with charging and power electronic systems. The life cycle inventory of the VW Golf has often been adapted and extrapolated for research purposes (Hauschild et al., Chapter 27, p.681).


Question: What has partly driven the growing interest in applying LCA to buildings in recent years?

The increased application of environmental certification to buildings.

Part of the growing interest in applying **life cycle assessment (LCA) to buildings** has been driven by the recognition that, as **operational energy use has been reduced** through better efficiency standards, the **embodied environmental impacts** of buildings — from materials, construction, maintenance, and end-of-life — have become more significant and harder to ignore.

Other important drivers include:

- **Climate policy and green building certification**
- **Demand for low-carbon materials and design**
- **Better LCA data, tools, and databases**
- **Greater awareness of whole-life environmental performance**, not just energy in use

So in short: **improved operational efficiency has shifted attention toward whole-life impacts, especially embodied carbon, helping drive LCA interest in buildings.**

Growing interest in applying LCA to buildings has been driven partly by increasing regulatory requirements on the energy performance of buildings, which have made building designs more complex through added materials and technologies to reduce operational energy use.
(Source 2, p.699, Chapter 28 “LCA of Buildings and the Built Environment”)

Part of the growing interest has been driven by increasing regulatory requirements on the energy performance of buildings, which have made building design more complex through added materials and technologies to reduce operational energy use; together with buildings’ long service lives, this makes LCA “an obvious part of the environmental evaluation of buildings” (Hauschild et al., Chapter 28, p.699).


Question: What advantage does the proposed method offer regarding future recycling rates and waste treatment technologies?

It can obviate (avoid) the uncertainties associated with future recycling rates and evolving waste treatment technologies.

A key advantage is **future robustness**: the proposed method can **account for changes in recycling rates and waste-treatment technologies over time**, instead of assuming today’s end-of-life conditions remain fixed.

This means it can:
- reflect **expected improvements in recycling**
- incorporate **technological advances in waste treatment**
- give **more realistic long-term environmental results**
- avoid bias from using **static, present-day assumptions** for products with long lifetimes

In short, it is better suited for assessing products whose end-of-life will occur under **future, potentially different waste-management systems**.

The proposed method “can obviate the uncertainties in future recycling rates and evolving waste treatment technologies.”
— Hauschild et al., *LCA: Theory and Practice*, Ch. 28 “LCA of Buildings and the Built Environment,” p. 710

The proposed method “can obviate the uncertainties in future recycling rates and evolving waste treatment technologies.” (Hauschild et al., *LCA: Theory and Practice*, Ch. 28, p. 710)


Question: What two problems arise from ignoring the disposal phase of durable goods and only including waste treatment performed in the study region over the assessment period?

It underestimates impacts from future waste treatment, while also ignoring that many goods with substantial embodied impacts may be recycled at end of life.

Two main problems arise:

1. **Incomplete life cycle / truncation error**
   Durable goods may be used for many years, so a large share of their end-of-life treatment happens **after the assessment period**. If disposal is ignored, the study misses those future waste management burdens and credits, underestimating the product system’s true impacts.

2. **Territorial bias / misallocation of waste treatment**
   If you count only waste treatment that occurs **within the study region during the period**, you include disposal of products sold long ago or imported from elsewhere, while excluding disposal of goods produced or sold in the study region but treated later or abroad. This breaks the link between the product and its end-of-life and can distort results through inconsistent geographic and temporal boundaries.

Ignoring the disposal phase in that way has “the double issue of”:

1. “underestimating impacts due to waste treatment in the future,” and
2. “simultaneously ignoring the fact that many goods with substantial embodied impacts may be recycled at end of life.”

— Hauschild et al., LCA: Theory and Practice, Chapter 28 “LCA of Buildings and the Built Environment,” p.710

Ignoring the disposal phase in that way has “the double issue of”:

1. “underestimating impacts due to waste treatment in the future,” and
2. “simultaneously ignoring the fact that many goods with substantial embodied impacts may be recycled at end of life.”

(Hauschild et al., *LCA of Buildings and the Built Environment*, p. 710)


Question: Which life cycle stage tends to dominate a building's environmental impacts, and how does this change as buildings become more energy efficient?

The use stage tends to dominate environmental impacts, but as buildings become increasingly energy efficient, life cycle impacts shift towards other stages.

Traditionally, the **use/operation stage** dominates a building’s life-cycle environmental impacts, mainly because of **heating, cooling, ventilation, lighting, and hot water energy use** over many decades.

As buildings become **more energy efficient**:

- **Operational impacts decrease**
- The relative importance of **embodied impacts** increases — especially from:
  - **material production**
  - **construction**
  - **maintenance/replacement**
  - **end-of-life**

So in conventional buildings, **operational energy** is usually the largest contributor, but in **low-energy or net-zero buildings**, **embodied carbon/impacts can become equal to or even greater than operational impacts**.

The use stage tends to dominate a building’s environmental impacts. As buildings become more energy efficient, environmental burdens shift toward other life cycle stages, so no single stage is certain to dominate in contemporary low-energy buildings. (Chapter 28, p.720; Chapter 28, p.702)

The **use stage** tends to dominate a building’s environmental impacts. It spans the building’s service life, and annual energy and material consumption accumulate over decades, so it has “traditionally contributed considerably to the calculated life cycle impacts” (e.g. 80–95% in cited studies) (Hauschild et al., **Ch. 28, p. 701**).

As buildings become more energy efficient, this pattern changes: **environmental burdens shift to other life cycle stages**, and for contemporary low-energy buildings “there is no single element or life cycle stage certain to dominate” the results (Hauschild et al., **Ch. 28, p. 720**; **p. 702**).


Question: In the life cycle stage sequence depicted in the ILCD Handbook's schematic for "open loop – different primary route" recycling, what stage directly follows Extraction, and what stage does that intermediate stage in turn directly precede?

According to the schematic in the ILCD Handbook, Extraction is directly followed by Material Production, which in turn directly precedes Part Production & Assembly. Thus, Material Production serves as the intermediate stage connecting Extraction to Part Production & Assembly in the life cycle sequence.

In the ILCD Handbook schematic for **“open loop – different primary route”** recycling:

- The stage **directly after Extraction** is **Material production**.
- That intermediate stage **directly precedes Use**.

So the sequence is:

**Extraction → Material production → Use**

In the schematic for “open loop – different primary route” recycling, **Extraction is directly followed by Material production1, which in turn directly precedes Assembly1**.
(Source: ILCD Handbook, Annex C, p.348)

In the ILCD schematic for “open loop – different primary route” recycling, **Extraction** is directly followed by **Material production1**, and **Material production1** in turn directly precedes **Assembly1** (“Extraction1 Material production1 Assembly1 Use1 Disposal1 Recycling …”) (ILCD Handbook, Annex C, p.348).


Question: Which materials are given as examples of goods that may be recycled at end of life?

Structural steel, aluminium, glass, and possibly precious metals in electronics.

Examples commonly given are **metals, glass, paper/cardboard, and many plastics**. In some contexts, **wood** and **concrete/aggregates** are also included as recyclable end-of-life materials.

Examples given are:

- High-density polyethylene — recycled and re-melted runners from a flow injection moulding process replacing virgin HDPE. (ILCD Handbook, p.346)
- Aluminium — refillable 5 l aluminium kegs for beer packaging. (ILCD Handbook, p.346)
- Glass, aluminium, steel, and PVC — in the window case study, examples of recycled materials replacing virgin materials are glass cullets, aluminium ingot, steel billet, and PVC granulate mix. (LCA: Theory and Practice, p.1083)

Examples given are:
- **Secondary metal bar** — as a valuable co-function produced from end-of-life recycling (**ILCD Handbook, p.182**).
- **High-density polyethylene** — recycled and re-melted runners replacing virgin HDPE in closed-loop recycling (**ILCD Handbook, p.346**).
- **Glass cullets, aluminium ingot, steel billet, and PVC granulate mix** — assumed to replace virgin materials at end of life in the window case study (**Hauschild et al., Ch. 39, p.1083**).


Question: Into how many stages is the life cycle of a food product split, and what are they?

Six stages: production and transportation of inputs to the farm, cultivation, processing, distribution, consumption, and waste management.

In life cycle assessment, a food product’s life cycle is commonly split into **5 main stages**:

1. **Raw material production**
   Farming, livestock raising, fishing, feed production, fertilizers, etc.

2. **Processing and manufacturing**
   Converting raw ingredients into the final food product.

3. **Packaging**
   Production and use of packaging materials.

4. **Distribution and retail**
   Transport, storage, refrigeration, and sale to consumers.

5. **Use and end-of-life**
   Consumer transport, cooking, storage at home, and disposal of food waste and packaging.

Sometimes studies group or rename stages slightly, but these are the standard life cycle stages for food products.

According to Chapter 29, p.723, the life cycle of a food product is split into six stages:

1. Production and transportation of inputs to the farm
2. Cultivation
3. Processing
4. Distribution
5. Consumption
6. Waste management

(Source: Hauschild et al., *LCA: Theory and Practice*, Chapter 29, p.723)

The life cycle of a food product is split into **six stages**:

1. **Production and transportation of inputs to the farm**
2. **Cultivation**
3. **Processing**
4. **Distribution**
5. **Consumption**
6. **Waste management**

Source: Hauschild et al., *LCA: Theory and Practice*, Chapter 29 “LCA of Food and Agriculture,” p. 723.


Question: Why do many LCA studies focus on the production of inputs and cultivation stages in cradle-to-farm gate studies?

Because these are the stages where most impacts typically occur, due to animal husbandry and manure handling, production and use of fertilisers, and the consumption of fuel to operate farm machinery.

Because in **cradle-to-farm gate LCA**, the system boundary ends at the farm gate, so the main environmental burdens usually occur in the stages that happen **before and on the farm**:

- **Production of inputs**: making fertilizers, pesticides, feed, seeds, fuel, and machinery can require a lot of energy and cause substantial emissions.
- **Cultivation or on-farm operations**: soil emissions, fertilizer application, irrigation, machinery use, manure management, and field activities often dominate impacts like:
  - climate change
  - eutrophication
  - acidification
  - energy use
  - water use

These stages get attention because they are often the **largest contributors** to total impacts within that boundary and are also where results are **most sensitive to management choices**.

So, many studies emphasize them because they are:
1. **Inside the defined system boundary**
2. **Usually the environmental hotspots**
3. **Critical for comparing farming practices and improvement options**

Many LCA studies focus on the production of inputs and cultivation stages in cradle-to-farm gate studies because agricultural production is important and the agricultural stage often bears the largest environmental impacts; accordingly, many food-product LCAs include only these first two stages. It is also often assumed that most impacts arise at the agricultural stage or that post-farm gate processes are identical.
(Hauschild et al., *LCA: Theory and Practice*, Ch. 29, pp. 725, 747, 750)

Many LCA studies focus on the production of inputs and cultivation stages in cradle-to-farm gate studies because:

- the agricultural stage is often assumed to bear the largest environmental impacts, and
- post-farm gate processes may be identical between alternatives, so researchers limit the study to the stages before the farm gate.

For food products, cradle-to-farm gate studies include only the first two stages—“inputs production and transportation” and the “agricultural stage”—and “the agricultural stage is often found to be the major contributor to many impact categories” due to nutrient and pesticide flows, livestock, and manure handling (Hauschild et al., LCA: Theory and Practice, Ch. 29, p.750). The chapter also states that such a study is often done “because it is assumed that most impacts arise at the agricultural stage or because the post-farm gate processes are identical” (Hauschild et al., Ch. 29, p.747).


Question: What happens to the raw agricultural product during the processing stage?

The raw agricultural product leaving the farm gate is converted into a food item that can be consumed by the user.

During the **processing stage**, the raw agricultural product is transformed into a more usable, stable, or marketable form. This can include:

- **Cleaning and sorting** to remove dirt, damaged material, or impurities
- **Drying, milling, pressing, peeling, cutting, or cooking** depending on the crop
- **Preservation** steps such as pasteurization, fermentation, freezing, or canning
- **Packaging** for storage, transport, and sale

In LCA terms, this stage often involves:
- **Energy use** for machinery, heat, and refrigeration
- **Water use** for washing or processing
- **Material inputs** such as packaging
- **Waste and by-products** generation, which may be discarded, treated, or reused

So, the raw product is essentially converted from harvested biomass into a processed product ready for distribution or further manufacturing.

During the processing stage, the raw agricultural product leaving the farm gate is converted into a food item that can be consumed by the user. It may also be converted into a packaged food item.
(Hauschild et al., *LCA: Theory and Practice*, Chapter 29, pp. 723, 728)

During the processing stage, “the raw agricultural product leaving the farm gate is converted to a food item that can be consumed by the user” (Hauschild et al., *LCA: Theory and Practice*, Ch. 29, p. 723). The chapter also defines processing as “any step to convert the raw farm product into a (packaged) food item” (Ch. 29, p. 728).


Question: Why can biogenic CO2 emissions be excluded from the impact assessment in this study?

Because they are formed from carbon that was taken up by the plant during its growth.

Biogenic CO₂ can be excluded when the study applies the common LCA assumption of **carbon neutrality over the assessed time horizon**.

Why:
- **Biogenic CO₂ comes from recently absorbed atmospheric carbon** during biomass growth.
- If the biomass is **sustainably regrown**, the CO₂ released at end of life is considered to be **balanced by prior uptake**.
- Therefore, it is often treated as **net zero for climate change** in the impact assessment, to avoid counting the same carbon twice.

This is appropriate only if the study assumes:
- the biomass is from **renewable/sustainably managed sources**,
- **land-use change and timing effects** are negligible or handled separately,
- and only **fossil CO₂** contributes to net addition of carbon to the atmosphere.

So, in this study, biogenic CO₂ is excluded because it is considered part of the **short-term natural carbon cycle**, unlike fossil CO₂.

Biogenic CO2 emissions can be excluded if the study consistently treats biogenic carbon as climate-neutral, since “Biogenic carbon can be considered either neutral or as contributing to climate change, depending on the approach, but this choice needs to be consistent throughout the study.”
— Hauschild et al., *LCA: Theory and Practice*, Ch. 35, p.903

Related context: biofuel CO2 is often treated as having a “neutral” effect because it is part of the biogenic carbon cycle.
— Hauschild et al., *LCA: Theory and Practice*, Ch. 2, p.10

Biogenic CO2 emissions can be excluded only if they are shown to be of little overall relevance and the omission is quantitatively justified under the study’s cut-off rules and goal definition; any such exclusion must then be made explicit in interpretation as a limitation of the results (European Commission – JRC, ILCD Handbook: General Guide for LCA, 2010, p.110).

Also, for biogenic carbon specifically, its treatment may vary—biogenic carbon can be considered neutral or contributing to climate change depending on the chosen approach—but that choice must be applied consistently throughout the study (Hauschild et al., LCA: Theory and Practice, Ch. 35, p.903).


Question: How did the contribution of wastewater treatment to global warming potential change when biogenic CO2 emissions were included versus excluded?

It contributed 17% of the impact potential when including biogenic CO2 emissions, but only 3% when excluding them.

Including biogenic CO2 makes the wastewater treatment stage appear to contribute more to global warming potential, sometimes substantially, because CO2 released from degrading biogenic carbon is counted in the GWP total.

Excluding biogenic CO2 lowers the reported GWP contribution of wastewater treatment, often making methane (CH4), nitrous oxide (N2O), energy use, and chemical inputs the dominant contributors instead.

So, in short:

- Included biogenic CO2 → wastewater treatment GWP increases
- Excluded biogenic CO2 → wastewater treatment GWP decreases

This difference can be large if the treatment process mineralizes a lot of biodegradable organic matter.

In the food and agriculture chapter, wastewater treatment contributed 17% of the global warming potential when biogenic CO2 emissions were included, but only 3% when they were excluded. (Hauschild et al., LCA: Theory and Practice, Ch. 29, p. 740)

Including biogenic CO2, wastewater treatment contributed 17% of the global warming potential; excluding biogenic CO2, it contributed 3%. The biogenic CO2 can be excluded because it comes from carbon taken up by plants during growth (Hauschild et al., *LCA: Theory and Practice*, Ch. 29 “LCA of Food and Agriculture,” p. 740).


Question: What percentage of the acidification potential was contributed by home storage and cooking, and what was its rank among contributors?

Home storage and cooking contributed 12% and was the second largest contributor to the acidification potential.

Home storage and cooking contributed about **14%** of the **acidification potential**, making it the **third-largest contributor**.

Home storage and cooking contributed 12% of the acidification potential and was the second contributor.

Chapter 29, p.740 (Hauschild et al., LCA: Theory and Practice — LCA of Food and Agriculture)

Home storage and cooking contributed **12%** of the **acidification potential** and was **the second contributor** among the life cycle stages considered (Hauschild et al., *LCA: Theory and Practice*, Ch. 29 “LCA of Food and Agriculture,” p. 740).


Question: The International Reference Life Cycle Data System is defined in a handbook published by the European Commission's Joint Research Centre. What key methodological phase of Life Cycle Assessment does that same handbook address through its detailed guidance?

The International Reference Life Cycle Data System (ILCD) is defined in the ILCD Handbook: General Guide for Life Cycle Assessment, published by the EC-JRC (European Commission-Joint Research Centre, Institute for Environment and Sustainability) as detailed guidance. That same handbook covers Scope definition as part of its comprehensive Life Cycle Assessment guidance.

It provides detailed guidance on the **Life Cycle Impact Assessment (LCIA)** phase of LCA.

More specifically, the **ILCD Handbook** from the European Commission’s Joint Research Centre includes extensive methodological recommendations for how inventory results are translated into environmental impacts.

It addresses **Life Cycle Assessment in general**, i.e. the **“General guide for Life Cycle Assessment – Detailed guidance”** of the ILCD Handbook (European Commission – JRC, **p.2**; also cited on **p.3**).

It addresses **Life Cycle Inventory analysis** through its detailed guidance in the **ILCD Handbook: General Guide for LCA** (**p.166**).


Question: In a consequential Life Cycle Assessment, short-term and long-term marginal processes are key modelling choices. Within which broader phase of the overall LCA framework do these marginal process decisions ultimately belong?

Marginal processes (both short-term and long-term) are part of LCI (Life Cycle Inventory) modelling, as they determine which processes are included in the LCI model based on consequential logic. LCI modelling, in turn, is part of Scope Definition — the phase of LCA in which analysts determine what to analyse and how, including decisions about background system modelling such as the selection of marginal electricity processes. Therefore, decisions about which marginal processes to include ultimately belong to the Scope Definition phase of an LCA.

They ultimately belong to the **Life Cycle Inventory (LCI) modelling phase**, specifically within **system modelling / modelling assumptions** for a **consequential LCA**.

More broadly in the ISO LCA framework, these choices are typically **set during goal and scope definition** and then **implemented in the inventory modelling**. So if you need the broader phase: **goal and scope definition**, with practical application in **LCI modelling**.

They belong to the **Life Cycle Inventory (LCI) analysis / inventory analysis phase**, specifically the system modelling step in consequential modelling.

Citations:
- **European Commission – JRC, ILCD Handbook (2010), Chapter 7 “Life Cycle Inventory analysis”, p.178**
- **Hauschild et al., LCA: Theory and Practice, Chapter 9 “Life Cycle Inventory Analysis”, p.135**

They belong in the **Life Cycle Inventory (LCI) analysis / system modelling phase** of the LCA framework, because consequential modelling guidance on identifying **short-term vs long-term marginal processes** is given under **“Life Cycle Inventory analysis - collecting data, modelling the system, calculating results”** (ILCD Handbook, **p.178**). This is consistent with consequential LCA being treated as part of **LCI modelling** (Hauschild et al., **Chapter 8, p.97**).


Question: Why are bio-based products such as biofuels and biomaterials receiving increasing attention as substitutes for fossil-based products?

Because fossil resources are limited, and their use is a major contributor to global warming and other environmental impacts.

Bio-based products such as biofuels and biomaterials are receiving more attention mainly because they can help address several problems linked to fossil resources:

- **Climate change mitigation:** They are made from renewable biomass, which can reduce net greenhouse gas emissions compared with fossil-based products, especially when sustainably sourced.
- **Reduced fossil resource depletion:** They lower dependence on finite oil, gas, and coal reserves.
- **Energy and material security:** Domestic biomass resources can improve supply security and reduce reliance on imported fossil fuels.
- **Policy support:** Governments promote them through climate, renewable energy, and circular economy policies.
- **Waste valorization opportunities:** Many bio-based products can be made from agricultural residues, forestry residues, and organic waste, improving resource efficiency.
- **Potential environmental benefits:** In some cases they may reduce impacts such as toxicity or non-renewable energy use, depending on the production system.
- **Technological progress:** Advances in biorefining, biotechnology, and materials science have made bio-based alternatives more feasible and competitive.

However, in LCA terms, bio-based does **not automatically mean environmentally better**. Their performance depends on factors such as land use, fertilizer use, water demand, processing energy, transport, and end-of-life treatment.

Bio-based products are receiving increasing attention because fossil resources are limited, and the use of fossil resources is a major contributor to global warming and other environmental impacts; therefore, bio-products have potential as substitutes for fossil-based products. Their potential is also high on the global political agenda because of dependence on fossil resources and the possibility of directly substituting fuels, chemicals, and materials conventionally produced from fossil resources.

(Hauschild et al., *LCA: Theory and Practice*, Ch. 30, pp. 755–756)

Bio-based products are receiving increasing attention because fossil resources are limited, and their use is “a major contributor to global warming and other environmental impacts,” so bio-products are seen as potential substitutes for fossil-based products (Hauschild et al., Chapter 30, p.755).

The chapter also notes a broader concern with “dependence on fossil resources,” which has put “the potential of bio-products as substitutes for fossil-based ones” high on the global political agenda (Hauschild et al., Chapter 30, p.756).


Question: What primary factor does the environmental profile of bio-products relative to their fossil counterparts depend on?

It is case specific and depends to a high degree on the feedstock used.

Primarily, it depends on the **biomass feedstock and how it is produced**.

In practice, the key driver is usually the **life-cycle impacts of biomass production**, especially:
- **Land use and land-use change**
- **Agricultural inputs** like fertilizer, pesticides, water, and energy
- **Yield and cultivation practices**
- **Transport and processing efficiency**

So, the environmental profile of bio-products versus fossil alternatives depends mainly on **the full life-cycle of the bio-based feedstock, especially land use and cultivation impacts**.

The environmental profile of bio-products relative to fossil counterparts primarily depends on the specific case, meaning it requires a case-specific LCA and inclusion of all relevant impact categories to avoid problem shifting (Hauschild et al., *LCA: Theory and Practice*, Ch. 30, p.755).

The environmental profile of bio-products relative to fossil counterparts primarily depends on the specific case and on including all relevant impact categories; the text states the “importance of conducting case specific LCAs for determining the environmental profile of bio-products relative to fossil ones” and of including all relevant impact categories to avoid problem shifting. (Hauschild et al., *LCA: Theory and Practice*, Ch. 30, p.755)


Question: In life cycle assessment, elementary flows are compiled from a specific system to support impact assessment — what broader economic structure does that system itself form a part of?

Elementary flows are matter or energy entering or leaving the product system (e.g., resources extracted from or emissions discharged into the environment). The inventory analysis compiles relevant data on elementary flows from the product system to support impact assessment. The product system, in turn, is part of the economic supply chain, since it is composed of unit processes linked by economic flows of goods, materials, services, energy, or waste. Therefore, elementary flows — compiled from the product system — are ultimately part of a broader economic supply chain.

In LCA, the system from which elementary flows are compiled is part of the **technosphere** — the broader human-made economic and industrial system of processes, products, transport, energy, and services.

Elementary flows are the exchanges between that technosphere and the **environment** (often called the ecosphere or biosphere).

In LCA, the system from which elementary flows are compiled is the **product system**, and that product system forms part of the **life cycle consisting of interlinked economic processes**. These processes include resource extraction, production, manufacture, use, waste processing, recycling/reuse, transport, and electricity generation, with inputs coming either from other processes or directly from the environment, and outputs going either to other processes or to the environment. (Guinée et al., *Handbook on LCA*, p.483; see also p.403)

The system forms part of “the life cycle,” which “consists of interlinked economic processes.” These economic processes include resource extraction, production, manufacture, use, waste processing, recycling/reuse, transport, and electricity generation. (Guinée et al., *Handbook on LCA: Operational Guide to the ISO Standards*, 2002, p. 483)


Question: When conducting LCA studies on biodegradable polymers, which waste handling method is often considered, and which option is rarely included?

Composting is often considered as the waste handling method, whereas digestion is rarely included.

In LCAs of biodegradable polymers, **industrial composting** is often considered as the main end-of-life waste handling method.
By contrast, **anaerobic digestion** is **rarely included** in many studies.

Some studies also compare landfill or incineration, but for specifically “biodegradable” options, composting is the most commonly modeled route.

For LCA studies on biodegradable polymers, composting is often considered, while landfill is rarely included.

Chapter 31, p.808.

For LCA studies on biodegradable polymers, **composting is often considered**, while **anaerobic digestion is rarely included**.
(Hauschild et al., *LCA: Theory and Practice*, chap. 31, p. 799)


Question: Under what condition can composting biodegradable materials be more beneficial than incineration, according to some studies?

Composting can be more beneficial than incineration if the compost is used for agricultural carbon soil replenishment.

Some studies find composting biodegradable materials can be more beneficial than incineration when the compost is actually needed and can replace other products or impacts—especially when it substitutes peat or mineral fertilizers and improves soil carbon/storage.

In short: composting tends to look better if the compost delivers real agricultural/soil benefits, rather than being treated as just a waste output.

Some studies suggest composting biodegradable materials can be more beneficial than incineration if the compost is used for agricultural carbon soil replenishment.
— Chapter 30, p.769

Some studies suggest composting biodegradable materials can be more beneficial than incineration **if the compost is used for agricultural carbon soil replenishment**.
**(Hauschild et al., *LCA: Theory and Practice*, Ch. 30 “LCA of Biofuels and Biomaterials”, p. 769)**


Question: What proportion of the initially sequestered carbon is likely to be released during composting of biodegradable polymers, and why?

Between 80% and all of the initially sequestered carbon is likely to be released, due to the polymers' ability to rapidly decompose, leaving little for soil replenishment and storage.

A large share—often most—of the carbon initially stored in a biodegradable polymer is released during composting, mainly as **CO₂** under aerobic conditions.

Typical rule of thumb:
- **~50–90% or more** of the polymer carbon can be mineralized to **CO₂**
- The remainder is usually split among:
  - **microbial biomass**
  - **stable organic matter/humus**
  - small residual undegraded fragments, depending on composting quality and polymer type

Why this happens:
- Composting is designed to promote **microbial breakdown** of organic carbon.
- Microbes use the polymer as a **carbon and energy source**, oxidizing much of it to CO₂.
- Only a smaller fraction is converted into **new biomass** or retained in compost as more stable carbon.

Important nuance:
- If composting is **anaerobic** or poorly managed, some carbon may be released as **CH₄**, which is much more climate-relevant than CO₂.
- The exact proportion depends on **polymer chemistry**, **composting conditions**, and **residence time**.

So in LCA terms, composting usually means that **temporary biogenic carbon storage is largely reversed at end of life**.

Between 80% and 100% of the initially sequestered carbon is likely to be released during composting of biodegradable polymers, because these polymers rapidly decompose, leaving little carbon for soil replenishment or storage.

Chapter 30, p.769 (Hauschild et al., LCA: Theory and Practice)

Between **80% and all** of the initially sequestered carbon is likely to be released during composting of biodegradable polymers, **because they rapidly decompose**; therefore, little carbon remains for soil replenishment and storage in soil (Hauschild et al., *LCA: Theory and Practice*, Ch. 30, p. 769).


Question: How do bio-products compare environmentally to fossil products across life cycle impact categories according to many LCA studies?

Bio-products are environmentally superior to fossil products in some life cycle impact categories, while the picture is often the opposite in others.

Across many comparative LCA studies, **bio-based products are not uniformly “better” than fossil-based ones**. The overall pattern is:

- **Usually better for climate change / fossil resource use**
  - Bio-products often show **lower greenhouse gas emissions** and **lower non-renewable energy/fossil depletion**, especially when biomass is sustainably sourced and carbon storage/substitution is credited.

- **Often worse for land-related and nutrient-related impacts**
  - They frequently have **higher land use**, **eutrophication**, and sometimes **acidification**, mainly due to agriculture/forestry inputs, fertilizer use, and runoff.

- **Mixed or highly variable for other categories**
  - **Water use**, **toxicity (human/ecotoxicity)**, **particulate matter**, **photochemical smog**, and **biodiversity** results vary widely by feedstock, farming practice, region, conversion technology, coproduct handling, and end-of-life assumptions.

Key reasons for variability:
- Type of biomass feedstock (crops, residues, wood, waste)
- Direct/indirect land-use change
- Agricultural intensity and fertilizer/pesticide use
- Energy source used in processing
- Allocation method for coproducts
- Product function and lifetime
- Recycling, biodegradation, incineration, or composting at end of life

**Bottom line:**
Many LCAs find bio-products provide **clear advantages in climate and fossil resource depletion**, but **trade-offs are common in other impact categories**, especially **land use and eutrophication**. So environmental superiority depends strongly on the specific product system and assumptions, not simply on being bio-based.

According to many LCA studies, bio-products are environmentally superior to fossil products in some life cycle impact categories, while the picture is often opposite in others; the comparison is case specific and highly dependent on the feedstock used (Hauschild et al., Chapter 30, p.755). Overall, the environmental performance is inconclusive from a general point of view, which is why all relevant impact categories should be included to avoid problem shifting (Chapter 30, p.761).

According to many LCA studies, bio-products are environmentally superior to fossil products in some life cycle impact categories, while in others the opposite is often found. The overall comparison is therefore case specific and depends strongly on the feedstock used. Reviews cited in the chapter note that bio-products often perform worse than conventional products for eutrophication, stratospheric ozone depletion, and in some cases acidification, and that results can also change substantially when land use change or indirect land use change emissions are included. This is why the chapter concludes that the overall environmental performance of bio-products versus fossil products is inconclusive in general and that all relevant impact categories should be included to avoid problem shifting. (Hauschild et al., Chapter 30, pp. 755, 760–761)


Question: What is the main focus of applying Life Cycle Assessment to chemicals and chemical products?

Evaluating the environmental performance of chemicals as well as of products and processes where chemicals play a key role.

The main focus is to evaluate the environmental impacts of chemicals and chemical products across their entire life cycle — from raw material extraction and synthesis, through manufacturing and use, to end-of-life treatment or disposal.

In practice, this is often used to:
- identify impact hotspots,
- compare alternative chemicals or processes,
- avoid burden shifting between life cycle stages,
- support safer and more sustainable product and process design.

The main focus is to evaluate the environmental performance of chemicals and of products and processes where chemicals play a key role across their life cycle stages. LCA also considers the life cycle of whole products or processes and evaluates their overall environmental performance rather than focusing only on specific hazardous chemicals.
(Hauschild et al., *LCA: Theory and Practice*, Ch. 31, pp. 783, 791)

The main focus is to **evaluate the environmental performance of chemicals, and of products and processes in which chemicals play a key role**. More specifically, LCA considers **the life cycle of whole products or processes** and evaluates their **overall environmental performance**, rather than focusing only on individual hazardous chemicals. (Hauschild et al., *LCA: Theory and Practice*, Chapter 31, pp. 783, 791)


Question: What life cycle stages are identified for chemical products such as pharmaceutical drugs or plant protection products?

Extraction of abiotic and biotic raw materials, chemical synthesis and processing, material processing, product manufacturing, professional or consumer product use, and end-of-life.

For chemical products like **pharmaceuticals** and **plant protection products (PPPs/pesticides)**, the life cycle is typically described in these main stages:

1. **Raw material acquisition**
   - Extraction/production of feedstocks, solvents, intermediates, active ingredients, excipients, and packaging materials.

2. **Chemical synthesis / manufacturing**
   - Production of the active substance and formulation of the final product.
   - Includes energy use, utilities, emissions, waste treatment, and process losses.

3. **Packaging**
   - Primary, secondary, and transport packaging production and filling.

4. **Distribution and transport**
   - Transport between suppliers, manufacturing sites, warehouses, pharmacies/hospitals/farms/retailers, and end users.

5. **Use phase**
   - **Pharmaceuticals:** administration to patients, storage, and possible losses.
   - **Plant protection products:** application in the field, equipment use, dilution, and emissions to air, soil, and water during/after application.

6. **Post-use fate / environmental emissions**
   - **Pharmaceuticals:** excretion of active residues/metabolites, wastewater treatment, and release to surface waters/soils.
   - **PPPs:** degradation, drift, runoff, leaching, and residues in soil, water, crops, and non-target environments.

7. **End-of-life / waste management**
   - Disposal of unused product, expired stock, contaminated packaging, treatment of hazardous waste, incineration, landfill, recycling where relevant.

In LCA, these are often grouped more simply as:

- **Upstream:** raw materials and precursor production
- **Core:** manufacture/formulation/packaging
- **Downstream:** distribution, use, emissions, and end-of-life

For **pharmaceuticals and PPPs**, the **use phase and environmental fate** are especially important because the active chemical is intentionally released or biologically active after use.

The identified life cycle stages are:

- extraction of abiotic and biotic raw materials
- chemical synthesis and processing
- material processing
- product manufacturing
- professional or consumer product use
- end-of-life

(Hauschild et al., *LCA: Theory and Practice*, Chapter 31, p.783)

For chemical products such as pharmaceutical drugs or plant protection products, the identified life cycle stages are:

- extraction of abiotic and biotic raw materials
- chemical synthesis and processing
- material processing
- product manufacturing
- professional or consumer product use
- end-of-life

(Hauschild et al., *LCA: Theory and Practice*, Chapter 31, p.783)


Question: What additional functions does propylene glycol provide in a shampoo that water does not?

Propylene glycol also acts as a stabiliser, humectant, and emulsifier.

Propylene glycol can do several jobs in shampoo that water alone does not do well:

- **Humectant**: helps attract and retain moisture, which can reduce dryness in hair and scalp.
- **Solvent / co-solvent**: dissolves fragrance oils, preservatives, botanical extracts, and some active ingredients that are poorly soluble in water.
- **Viscosity / texture support**: can help improve product feel and flow, though it is not mainly a thickener.
- **Freeze–thaw and stability aid**: helps keep the formula stable over temperature changes.
- **Penetration enhancer**: can increase delivery of some ingredients to hair or scalp.
- **Preservative booster**: can support antimicrobial preservation, though it is usually not the main preservative.

Water mainly acts as the **base/diluent**, while propylene glycol adds these functional performance benefits.

Propylene glycol in shampoo provides additional functions as a stabiliser, humectant, and emulsifier beyond water alone. (Hauschild et al., *LCA: Theory and Practice*, Ch. 31, p. 800)

Propylene glycol provides additional shampoo functions as a **stabiliser, humectant, and emulsifier**; water alone does not. This is stated where “water plus a stabiliser plus a humectant plus an emulsifier is functionally equivalent to propylene glycol in shampoo” (Hauschild et al., **Chap. 31, p. 800**).


Question: Which chemicals management frameworks and concepts is LCA discussed in relation to?

Risk assessment, green and sustainable chemistry, and chemical alternatives assessment.

LCA is commonly discussed in relation to several **chemicals management frameworks and concepts**, especially where broader environmental decision-making is needed beyond hazard or exposure alone. Key ones include:

- **Life Cycle Management (LCM)**
  LCA is a core tool within LCM for managing environmental impacts of chemicals and products across the full life cycle.

- **Sustainable Chemicals Management / Sustainable Chemistry**
  LCA is used to compare chemicals, formulations, and processes from a broader sustainability perspective.

- **Green Chemistry**
  LCA is often paired with green chemistry to check whether a “greener” synthesis or substitute actually reduces impacts across the full life cycle.

- **Alternatives Assessment / Chemical Substitution**
  LCA helps avoid regrettable substitution by comparing candidate substitutes on life-cycle environmental impacts.

- **Risk Assessment and Risk Management**
  LCA is frequently discussed alongside these, since risk assessment focuses on specific hazards/exposures, while LCA evaluates broader potential environmental burdens across stages and impact categories.

- **Product Stewardship / Integrated Product Policy**
  LCA supports decisions on chemical-containing products from raw material extraction through use and end-of-life.

- **Circular Economy**
  LCA is used to assess recycling, reuse, recovery, and material loop options for chemicals and chemical-containing products.

- **Environmental Footprinting / Sustainability Assessment**
  LCA underpins carbon footprint, water footprint, and broader environmental footprint approaches relevant to chemicals.

- **Eco-design / Design for Environment (DfE)**
  LCA informs design choices for chemical products and processes early in development.

- **Regulatory chemicals policy discussions**
  LCA is often referenced in discussions around frameworks such as **REACH**, **SAICM**, and broader chemicals policy, mainly as a complementary tool rather than a substitute for hazard-based regulation.

In short, LCA is most often linked to **green chemistry, sustainable chemistry, alternatives assessment, risk assessment, product stewardship, and circular economy** thinking.

LCA is discussed in relation to:

- Chemical management strategies broadly — “we overview strategies for chemical management, focusing particularly on life-cycle assessments of chemicals production processes and chemical products” (Hauschild et al., Ch. 31, p.785).
- Main chemical management tools / conceptual relationships — “31.1 Conceptual relationships of main chemical management tools” (Hauschild et al., Ch. 31, p.787).
- Chemical Alternatives Assessment (CAA) — “CAA takes the ‘producer’ perspective similarly to LCA… The main difference between CAA and LCA is…” (Hauschild et al., Ch. 31, p.791).
- Different chemicals management approaches — via “dichotomous perspectives followed in different chemicals management approaches” (Hauschild et al., Ch. 31, p.789).

LCA is discussed in relation to these chemicals management frameworks and concepts:

- Chemical management tools / conceptual relationships of main chemical management tools (Hauschild et al., ch. 31, p. 787).
- Chemicals production processes and chemical products, within strategies for chemical management (Hauschild et al., ch. 31, p. 785).
- Chemical Alternatives Assessment, CAA, contrasted with LCA in terms of producer perspective and focus (Hauschild et al., ch. 31, p. 791).
- Multiple chemicals and multiple receptors, as characteristics in different chemicals management approaches (Hauschild et al., ch. 31, p. 789).


Question: Why would comparing propylene glycol and water using a functional unit defined solely by their solvent function be problematic?

Because such a solvent-based functional unit would not capture the additional functions propylene glycol provides (e.g. stabiliser, humectant, emulsifier) that water does not, biasing the comparison.

Because **“solvent” alone is not a sufficiently specific function** for a meaningful LCA comparison between **propylene glycol (PG)** and **water**.

Key problems:

- **They do not deliver the same technical performance.**
  A functional unit must reflect the actual service provided. PG and water differ strongly in:
  - solvency power
  - polarity
  - viscosity
  - boiling/freezing point
  - volatility
  - compatibility with solutes and formulations

- **Amount needed may differ greatly.**
  If one solvent dissolves a substance better, less may be required to do the same job. Comparing “1 kg of solvent” or “1 liter of solvent” would therefore not represent equivalent function.

- **The relevant function is often broader than solvency.**
  In many applications PG is used not just as a solvent, but also for:
  - humectancy
  - antifreeze behavior
  - heat transfer
  - preservation/formulation stability
  Water usually does not provide the same combination of functions.

- **Use-phase conditions can change the comparison.**
  If temperature control, evaporation losses, corrosion, sterility, or product stability matter, the two solvents may require different supporting processes.

So, a functional unit based only on “solvent function” is problematic because it **fails to ensure functional equivalence**. A better functional unit would specify the actual service, such as:
**“delivery of X concentration of solute in formulation Y under condition Z for time T.”**

Because it would ignore the multi-functionality of propylene glycol. While both water and propylene glycol can serve as solvents, propylene glycol may also act as a stabiliser, humectant, and emulsifier, which water does not. So a solvent-only functional unit would compare products fulfilling distinct overall functions and bias the LCA unless all relevant functionalities are included and system expansion is applied if needed.
(Hauschild et al., *LCA: Theory and Practice*, Chapter 31, p. 800)

Because such a functional unit would compare products with distinct overall functions and therefore bias the study. While both water and propylene glycol can act as solvents, propylene glycol also provides additional functions that water does not, such as stabiliser, humectant, and emulsifier. So a solvent-only FU would fail to capture the multifunctionality of propylene glycol; a more appropriate FU should cover all relevant functionalities, with system expansion if needed (e.g. water plus a stabiliser plus a humectant plus an emulsifier as the equivalent system). (Hauschild et al., *LCA: Theory and Practice*, Chapter 31, p. 800)