GHG Calculation for VS (VSME) Reporting: A Practical Guide
By Dr. Max Rosvall Välme, PhD in Strategic Sustainable Development, Uppsala University · Reviewed by Morten Rosén
GHG calculation for the Voluntary Standard (VS, formerly VSME) means estimating your greenhouse gas emissions using the GHG Protocol Corporate Standard, then reporting them under disclosure B3. The Basic Module requires total energy consumption in MWh and gross Scope 1 and 2 emissions in tCO₂eq.
Quick facts
- The Voluntary Standard (VS, formerly VSME) references the GHG Protocol Corporate Standard (2004) as its method.
- Disclosure B3 covers energy and greenhouse gas emissions in the Basic Module.
- Required: total energy consumption in MWh with a breakdown, and gross emissions in tCO₂eq.
- Scope 3 is not required in the Basic Module. It sits in the Comprehensive Module, where relevant.
- Two calculation approaches: activity-based (physical quantities) and spend-based (financial data).
- Emissions are calculated as activity data × emission factor.
How do you calculate greenhouse gas emissions?
You multiply activity data by an emission factor. Activity data is what your company consumed or spent, such as litres of diesel or kWh of electricity. The emission factor converts that quantity into tonnes of CO₂ equivalent. The GHG Protocol defines the method.
Every emissions figure you will ever report comes from this one equation. The difficulty is never the arithmetic, it is getting reliable activity data and choosing the right factor for it. That is where first-time reporters lose weeks.
What is the difference between activity-based and spend-based calculation?
Activity-based calculation uses physical quantities, such as litres of fuel or kWh of electricity, and produces the most accurate result. Spend-based calculation uses financial data with average emission factors per euro spent, and produces a defensible estimate faster when primary data is missing.
Neither is wrong. They answer the same question at different resolutions. My advice to most first-time reporters is to start spend-based to get a complete baseline across the whole company, then go back and refine the few categories that dominate your footprint with activity data. That sequence gets you a report this quarter instead of next year. The detailed trade-off is covered in the emission factor library.
What emissions does the Voluntary Standard require you to calculate?
The Basic Module requires total energy consumption in MWh with a breakdown, and gross Scope 1 and location-based Scope 2 emissions in tCO₂eq. Scope 3 belongs to the Comprehensive Module and is reported only where it yields relevant information.
This is narrower than a full ESRS inventory, and deliberately so. If you prepared for CSRD you likely scoped all three scopes plus 15 Scope 3 categories. Under VS you can report a complete, compliant Basic Module without touching Scope 3 at all. For the full picture of what each scope covers, see Scope 1, 2 and 3 emissions explained.
What are emission factors, and where do they come from?
An emission factor is a coefficient that converts an activity into greenhouse gas emissions, for example kg CO₂eq per litre of diesel or per kWh of grid electricity. Factors come from national inventories, international databases and sector studies, and they are updated periodically.
Two things matter when choosing factors. First, geography: grid electricity factors vary enormously between countries, so a Swedish and a Polish facility using identical amounts of electricity will report very different Scope 2 emissions. Second, vintage: factors change year to year, so your reporting year and your factor year should match.
Which method does the Voluntary Standard require for Scope 2?
The Voluntary Standard requires the location-based method for Scope 2. Location-based means you apply the average emission factor of the electricity grid you draw from, rather than the contractual factor from a specific supplier agreement.
The alternative, market-based accounting, reflects renewable energy contracts and guarantees of origin. It is useful for showing procurement decisions, but it is not what the Basic Module asks for. If you report both, label them clearly.
How long does a first GHG calculation take?
For a mid-sized company with reasonably organised financial and energy data, a first spend-based baseline is realistic within days rather than months. Activity-based refinement of the largest categories typically follows over the next reporting cycle.
The variable is data availability, not methodology. Companies that already track fuel purchases, energy bills and spend by category move quickly. Companies pulling data from several disconnected systems spend most of their time on collection.
What is the easiest way to calculate emissions for a VS report?
Use a tool that maps activity or spend data to emission factors automatically and outputs results in the format disclosure B3 expects. This removes manual factor look-ups, unit conversions and spreadsheet reconciliation, which is where most of the time and most of the errors come from.
Future Fluent's GHG calculator covers Scope 1 through 3, activity-based or spend-based, against a database of emission factors, and produces figures ready for the Voluntary Standard's B3 disclosure. You start free with Scope 1 & 2, no credit card — Scope 3 is part of Professional.
Calculate your emissions free →
Frequently asked questions
Which GHG standard does the Voluntary Standard use?
The Voluntary Standard references the GHG Protocol Corporate Accounting and Reporting Standard (2004 version) for estimating greenhouse gas emissions.
Do I need Scope 3 for a VSME report?
Not for the Basic Module. Scope 3 appears in the Comprehensive Module, and only where it yields relevant information.
Is spend-based calculation acceptable?
Yes. Spend-based calculation is a recognised approach when primary activity data is unavailable, though activity-based data produces more accurate results.
What unit are emissions reported in?
Tonnes of CO₂ equivalent (tCO₂eq). Energy consumption is reported in megawatt hours (MWh).