Bridging the purpose–method gap: development of a mapping approach for selection of scope 2 accounting methods

During the revision of the GHG Protocol's scope 2 guidance, debates on addressing existing accounting issues have intensified. Prominent market-based accounting proposals include variations of “hourly energy matching” and “carbon matching”, but uncertainty around their underlying accounting purposes has caused confusion. To address this, we reviewed more than 250 GHG accounting purposes from the literature and categorized them into 18 thematic groups. Based on this review, we propose a four-step mapping approach to assess the conceptual alignment between scope 2 accounting methods and their stated purposes: (1) define specific purposes using an abstraction hierarchy; (2) link purposes to an accounting framework: attributional (physical), consequential (physical), or performance (non-physical); (3) identify accounting requirements: deliverability and additionality; (4) select a suitable matching method: energy matching or carbon matching. Applying this approach to three method proposals submitted to the 2023 scope 2 revision process, revealed inconsistencies between stated purposes, requirements, and proposed methods, with all proposals aligning with performance accounting despite the stated purposes suggesting otherwise. To improve the GHG Protocol's scope 2 guidance, we recommend either incorporating deliverability and additionality requirements into physical inventory accounting or explicitly labeling it as performance accounting. Without such alignment, misleading claims are likely to persist.