What is PCR?

The most key issue in creating an EPD is life cycle assessment, which is usually prepared based on international standards such as ISO 14025. Life cycle assessment tries to determine the flow of materials in the product and calculate the effects of this flow, such as the amount of CO2 emitted and the consumption of resources and energy during this cycle.
Product Category Rules (PCR) are a set of rules, requirements, and guidelines for the development of Environmental Product Declarations (EPD) for one or more product categories.
Product category rules are a natural step in providing the type of information that is standardized across a group of products or materials with similar performance
Meanwhile, construction products need rules that guarantee comparability for specific products. Otherwise, the range of possible interpretations when calculating EPD data for construction would be enormous. EN 15804 standard can be considered as a reference for PCR.
There are currently many PCRs available in the PCR library. 
There are many PCRs because each group is associated with a PCR that focuses on the type of environmental impact unique to that group.