1.1 This guide illustrates alternative allocation approaches that provide options for modeling secondary material flows and related recycling scenarios within a life cycle assessment (LCA) study. It helps practitioners characterize and understand materials recycling across industries; provides the available methodologies for consideration of the environmental impacts that are attributed to material and product flows in LCA; aids in assessment of the overall life cycle of systems and understanding of materials; and supports life cycle management.

1.2 The guide is not intended to contradict or circumvent the LCA provisions of ISO 14025, ISO 14040, ISO 14044, ISO 14067, ISO/TR 14049, or ISO 21930. When conflicts arise related to LCA, the guidance of those ISO standards takes precedence.

1.3 The following seven material-specific appendixes are included:

1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.