How companies measure emissions: building a GHG inventory step by step
A step-by-step guide to a company greenhouse gas inventory: boundaries, activity data, emission factors from CEA and IPCC, a worked calculation, base year, data quality, verification under ISO 14064-3, and where an SME can start.
Step 6: How do you choose and protect a base year?
The base year is the year you compare against. The GHG Protocol Corporate Standard (2004) requires companies to choose and report a base year for which reliable data exist, and to set a recalculation policy. If the company later buys or sells a plant, outsources a process or finds a major error, base-year emissions should be recalculated so the trend stays fair. Define in advance what counts as a "significant" change and write it down.
Sources: GHG Protocol Corporate Accounting and Reporting Standard (revised edition, 2004); GHG Protocol Corporate Value Chain (Scope 3) Standard (2011); GHG Protocol: key standard development updates FAQ (29 July 2026); ISO 14064-1:2018 Greenhouse gases, Part 1 (ISO catalogue); ISO 14064-3:2019 Greenhouse gases, Part 3 (ISO catalogue); India GHG Program (WRI India, CII, TERI); India GHG Program: Road Transport Emission Factors technical paper, version 1.0 (2015, draft); Central Electricity Authority: CO2 Baseline Database for the Indian Power Sector; IPCC 2006 Guidelines for National Greenhouse Gas Inventories, Volume 2 Energy, Chapter 1 and Chapter 2; IPCC 2019 Refinement to the 2006 IPCC Guidelines; IPCC AR6 Working Group I (2021), Chapter 7, Table 7.15; UK Government: Greenhouse gas reporting conversion factors 2026 (DESNZ); SEBI: Format of BRSR Core, Annexure I (July 2023); SEBI circular SEBI/HO/CFD/CFD-PoD-1/P/CIR/2025/42 (28 March 2025); Central Electricity Authority, CO2 Baseline Database for the Indian Power Sector, User Guide Version 22.0 (August 2026); MoEFCC, India First Biennial Transparency Report (BTR-1) to the UNFCCC
This article was prepared with AI assistance and checked by the GreenEye team against the sources shown in each section.
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