How should the "allocation principles and allocation methods" of occupied resources be carried out in the calculation of product carbon footprint inventory? 

Product carbon footprint inventory calculation is a complex process that involves quantifying greenhouse gas emissions at all stages of a product's lifecycle. When conducting a carbon footprint inventory, "allocation principles" and "allocation methods" are two key concepts, especially when dealing with multi-product systems or shared processes and systems. The following is a detailed explanation and application guide for these two concepts: 

I. Definition of Distribution Principles Distribution principles refer to the principles of distributing inputs and outputs, including environmental impacts, to different products or functions in a multi-product system. This is necessary because in many production processes, a single process can produce multiple products or by-products, which requires that resource use and emissions be allocated equitably across individual products: 

1.System Boundary Expansion: 

The preferred method is to extend the system boundary, incorporating additional processes to provide the same functionality, thus avoiding the need for assignment. If possible, avoid allocation by modifying system boundaries. For example, treat by-products as standalone products and calculate their carbon footprint separately. Among the principles of product carbon footprint allocation, "system boundary expansion" is a specific approach aimed at solving the allocation problem in multi-product systems. When a production process produces multiple products or by-products, it is essential to decide how to distribute the environmental burden of that process, such as greenhouse gas emissions, to individual products. System boundary expansion is a way to avoid traditional allocation problems, and its core idea is to avoid the need for allocation by modifying the system boundaries of life cycle assessment (LCA). 

•  Principle of System Boundary Expansion The system boundary expansion method involves expanding the system boundary to include a product or by-product in an alternative production process. This means that, rather than trying to assign the environmental burden of a process to multiple products, the system boundary extension considers treating by-products as separate products and evaluating what environmental burden they would have if they were not produced as part of the original process but were produced by other means.

•  Implementation Step 

A.  Identify By-Products: Identify all products and by-products generated during the production process.

B.  Evaluate alternative production processes: For each byproduct, evaluate which production processes and their corresponding environmental burdens would be required if the byproduct were produced independently. 

C.  Modify System Boundaries: Incorporate these alternative production processes into product lifecycle assessments, expanding the original system boundaries. 

D. Computational Environmental Burden: Based on the expanded system boundary, calculate the total environmental burden of the product, including direct and indirect impacts. 

• Advantages and Limitations 

• Pros: Avoids the subjectivity and uncertainty that traditional distribution methods may introduce. 

• Provides a more comprehensive way to assess the environmental impact of products, especially if the by-products have significant environmental value. 

• Limitations:

• Implementing system boundary expansion may require additional data and analysis, adding complexity to the assessment.

•  For some products, finding a suitable alternative production process can be challenging, or data on alternative processes may not be readily available. 

• System boundary expansion offers an innovative approach to addressing allocation in product carbon footprints, particularly in multi-product systems. However, proper implementation of this approach requires a deep understanding of life cycle assessment and a thorough understanding of the products and processes involved. 

2.  Physical Allocation: 

Allocate environmental loads based on physical units like weight, volume, or energy content. This approach is suitable for those situations where physical properties are directly related to environmental impact. When system boundary expansion is not feasible, it should be allocated according to physical relationships, such as mass, energy, or volume ratios. 

• Principle of Physical Distribution The core idea of physical distribution is that each product or by-product should bear the environmental burden of a shared process proportional to its physical quantity. This approach assumes that the environmental impact of the process is directly proportional to the physical properties of the product, such as mass, volume, or energy. 

•  Implementation Steps : 

1.Identify the stages in the production process that result in multiple products or by-products. 

2.Choose the distribution base: Choose the appropriate physical quantity as the distribution base based on product characteristics, commonly including weight, volume, or energy content.

3. Collect data: For each product or by-product, collect the corresponding physical quantity data. 

4.Calculate the allocation ratio: Based on the physical quantity data of each product, calculate their share in the environmental burden of the shared process. 

5.Distribute environmental burdens: Allocate the environmental burden of the shared process to individual products or by-products according to the calculated proportion. 

• Advantages and Limitations 

• Pros: 

1.Intuitive and Easy to Understand: Physical distribution is based on clear physical quantities, making the distribution process relatively transparent and easy to understand. 

2.Objectivity: This approach reduces the impact of subjective judgments due to quantifiable physical properties. 

•  Limitations: 

A.  Does not necessarily reflect actual environmental impact: There is not always a direct proportional relationship between physical properties and environmental impact, especially when environmental influence factors vary greatly between different products

 B. Applicability Limitations: For certain processes or products, it may be difficult to find a suitable physical quantity as the basis for dispensing. 

C.Physical allocation is an effective way to handle the distribution of environmental burdens in multi-product systems, especially when there is a clear correlation between the physical properties of a product and its environmental impact. However, when selecting a dispensing method, detailed considerations should be given to product characteristics and the specific circumstances of the production process to ensure that the dispensing results can reasonably reflect the environmental impact of each product. 

3.Economic distribution: 

If physical distribution is not feasible, it can be allocated according to economic value, i.e., the environmental burden is distributed in proportion to the economic value of the product. The environmental impact is distributed according to the economic value of the product. This approach is particularly useful when the physical properties of a product are not directly related to its environmental impact. 

• Principle of Economic DistributionEconomic distribution takes into account that in some cases, the physical properties of a product, such as weight or volume, may be disproportionate to its contribution to its environmental impact. In these cases, the market value or economic contribution of the product is seen as a more suitable basis for distribution. 

•  Implementation Steps :

1. Identify the stages in the production process that result in multiple products or by-products. 

2.Evaluate Economic Value: For each product or byproduct, determine its value or economic contribution in the market. 

3.Calculate the distribution ratio: Based on the economic value of each product, calculate their share in the environmental burden of the sharing process. 

4.Distribute environmental burdens: Allocate the environmental burden of the shared process to individual products or by-products according to the calculated proportion. 

• Advantages and Limitations 

•   Advantages: 

1.Reflecting Economic Contribution: In some cases, economic allocation provides a more accurate reflection of the product's contribution to shared resources and environmental burdens. 

2.Suitable for Situations Where Physical Properties Are Not Correlated: When the environmental impact of a product is not directly related to its physical properties, economic distribution offers a viable alternative. 

•   Limitations: 

1.Market Value Fluctuations: The economic value of products may fluctuate with changes in market conditions, which may lead to instability in distribution ratios. 

2.Ignoring the Physical Basis of Environmental Impact: Economic allocation may not accurately reflect the actual environmental burden during product production. 

3.Computational Complexity: Determining the market value of a product can be more complex than allocation based on physical quantities, especially in changing market conditions. 

4.Economic distribution is a distribution method that applies in specific situations, especially when the environmental impact of a product is more related to its market value. However, when choosing this allocation method, one should carefully consider its potential limitations and challenges, and evaluate its suitability on a case-by-case basis. 

II.Distribution method 

The distribution method should choose the method that best reflects the distribution of resources and environmental burden in the actual production process. These methods include: 

1.Direct allocation method: Allocation is based on physical or economic flows measured or calculated directly. 

2.Alternative Approach: When direct measurement is not feasible, data from alternative products or processes can be used for distribution. 

3.Split Unit Processes: Divide multifunctional processes into single-functional processes so that the environmental burden of each process can be calculated separately. 

III.Standards and Guidelines 

In addition to ISO 14067:2018, there are other standards and guidelines that can be used to guide the calculation and allocation of a product's 

carbon footprint, including:

1. ISO 14040:2006: Provides life cycle assessment principles and frameworks, including target and scope definition, life cycle inventory analysis (LCI), life cycle impact assessment (LCIA), and interpretation of results.

2. ISO 14044:2006: The methodology for life cycle assessment is specified in detail, including specific application guidelines for allocation rules.

3. Product Category Rules (PCR) (Domestic): Guidelines for ensuring consistency and comparability of product carbon footprint labels, advanced 

guidelines for combining PCR carbon footprint label inventory calculations within the same product category. When calculating and reporting the 

carbon footprint of products, adhering to ISO 14067:2018 and other relevant ISO standards is key. This not only helps ensure the reliability and 

consistency of results but also facilitates comparison and communication between different organizations.