The importance of a good GHG inventory

This week, we want to discuss the importance of developing a good Greenhouse Gas (GHG) inventory. As we’ve all heard by now, the International Sustainability Standards Board (ISSB) has introduced new global standards for corporate sustainability reporting which are now mandatory for publicly listed companies in Mexico as of next year’s reporting cycle (in 2026). As we have discussed in previous blogs, the S2 standard provides guidance on how companies should report climate-related risks and opportunities.

The main goal of ISSB is to help organizations report sustainability-related risks and opportunities that could reasonably affect their cash flow, access to financing, or cost of capital in the short, medium, or long term. Since climate is considered one of the biggest risks for the planet, ISSB asks all companies to report all three scopes of GHG emissions every year.

What are the challenges around GHG emission accounting?

Measuring GHG emissions can be challenging, particularly for smaller companies that face limited data availability and high implementation costs. To simplify the process, many rely on specialized advisory firms. For more budget-friendly options, online platforms may offer accessible tools tailored to smaller operations. Having said that, companies first need to fully understand what goes into emissions accounting to make sure that what they are doing makes sense from a theoretical standpoint.

How to Calculate Your GHG Emissions in 5 Simple Steps?

Creating a GHG emissions inventory is the foundation for climate-related reporting. It involves identifying and consolidating emissions from operations where the company has ownership or control and mapping them all the way through to all facilities, geographies, business units, and processes included in its value chain.

Tackling your company’s carbon footprint starts with knowing where emissions come from. Here’s a streamlined guide to measuring greenhouse gas (GHG) emissions:

1. Identify Emission Sources

Understand which parts of your operations consume energy—like fuel use, electricity, logistics, or production processes. Classifying these emissions helps pinpoint where action is needed.

2. Classify Emissions by Scope

Use the GHG Protocol’s three scopes to categorize your emissions:

• Scope 1 – Direct emissions from sources you own or control (e.g., boilers, company vehicles).
• Scope 2 – Indirect emissions from purchased electricity, steam, or heat.
• Scope 3 – All other indirect emissions from your value chain (e.g., raw materials, product use, business travel). This one’s the trickiest to measure—but often the largest.

3. Gather Activity Data & Emission Factors

Collect the data that quantifies your emissions—like liters of fuel used or kWh of electricity consumed. Then match it with the right emission factors (how much CO₂ per unit of activity).

4. Use Calculation Tools

Apply standard tools or software (like those from the GHG Protocol or government agencies) to crunch the numbers and calculate total emissions.

5. Consolidate & Report

Roll everything up into a company-wide footprint. This helps track progress, set reduction targets, and meet reporting requirements.

Pro Tip: If you are doing this alone, start with Scopes 1 and 2—they’re simpler to measure. Then prioritize the biggest Scope 3 hotspots, such as supply chain emissions or product use.

GHG accounting can get complex, especially when it comes to Scope 3. Don’t worry if your first inventory isn’t perfect—this is a learning process. What matters most is getting started, building internal know-how, and improving your accuracy over time. Progress, not perfection, is the goal.

I hope you found this interesting. As usual, if there is anything we can help you with, or if there is an ESG topic you would like to know more about, please let us know.

Best,

Marimar

CEO, Miranda ESG