Answer: Before the release of the ISO14064 series of standards, there was no unified procedure and method for greenhouse gas inventory and verification. All parties involved in related activities decided and adopted some inventory and verification methods on their own. Many practical cases adopted or referred to the methods and procedures in the GHG protocol published by WBCSD/WRI. Due to inconsistencies in methods and procedures, it is difficult to obtain comparable results for greenhouse gas inventory and validation at this time.

This situation has changed since the release of the ISO 14064 series of standards. The current situation is that enterprise greenhouse gas inventory is generally conducted based on ISO 14064-1:2006 "Greenhouse gases - Part 1: Specification and guidelines for quantification and reporting of greenhouse gas emissions and removals at the organizational level"; Greenhouse gas verification is generally conducted in accordance with ISO 14064-3:2006 "Greenhouse gases - Part 3: Specifications and guidelines for the approval and verification of greenhouse gas declarations".