Every credible net-zero journey begins with a single, unglamorous question: how much are we actually emitting? For most businesses, especially those encountering carbon accounting for the first time, the answer feels impossibly complex. But building your first emissions inventory does not have to be daunting. It is, at its core, a data exercise — systematic, repeatable, and deeply clarifying once you start.
Think of an emissions inventory as your organisation’s carbon fingerprint. It captures every significant source of greenhouse gas emissions tied to your operations, translating activity — electricity consumed, kilometres driven, fuel burned, materials purchased — into a common unit: tonnes of CO₂ equivalent (tCO₂e). That number becomes your baseline, your benchmark, and your starting point for meaningful reduction.
This guide walks you through each step, from defining your boundaries to documenting your results. If you are working through our Carbon Accounting & Net-Zero Series, this is Step 1 of your measurement journey.
Step 1: Define Your Organisational Boundary
Before you collect a single data point, decide what is in your inventory and what is out. This is called setting your organisational boundary.
For most small and mid-sized businesses, the answer is straightforward: include all business locations, vehicles, and activities that you own or control. If you have multiple offices, include all of them. If you lease equipment, apply the operational control approach — if you control how it runs, it belongs in your inventory.
The GHG Protocol, the globally recognised standard for emissions accounting, offers two main approaches: equity share (based on financial ownership) and operational control (based on who manages day-to-day operations). For most businesses in India, operational control is the simpler and more practical starting point.
Step 2: Choose Your Reporting Period
An emissions inventory covers a defined time window — almost always 12 months. For your first inventory, align this with your financial year so that cost data and emissions data sit in the same period and comparisons are straightforward.
India’s financial year runs April to March. If your organisation follows a calendar year or a different internal cycle, that is fine too — just stay consistent. The most important rule: use the same reporting period every year so you can track real progress rather than seasonal noise.
Step 3: Identify Your Emission Sources (Scope by Scope)
The GHG Protocol organises emissions into three scopes. Your first inventory should cover Scope 1 and Scope 2 at minimum, with Scope 3 added progressively over time.
Scope 1 — Direct emissions: These come from sources you own or control directly. Common examples include fuel burned in company vehicles, diesel used in generators, LPG used in office kitchens, and refrigerant leaks from air conditioning systems.
Scope 2 — Purchased electricity: This covers the greenhouse gas emissions associated with the electricity you buy from the grid. In India, the Central Electricity Authority (CEA) publishes an annual emission factor for grid electricity — use the most recent figure for your state or the national average.
Scope 3 — Indirect value chain emissions: Everything else, from employee commuting to purchased goods to business travel by air or rail, falls here. These are often the largest part of a business’s total footprint but require more data to measure. For a first inventory, focus on the most material Scope 3 categories — typically business travel and employee commuting — and expand from there. You can explore more about net zero commitments and frameworks as your accounting matures.
Step 4: Collect Activity Data
Activity data is the raw input for your calculations: litres of diesel, kilowatt-hours of electricity, kilometres driven, flights taken. Gather it from the most direct and verifiable sources available.
- Electricity: Pull monthly consumption figures from electricity bills (in kWh). If you have multiple meters across different premises, collect all of them.
- Fuel: Use fuel purchase receipts, logistics records, or vehicle fuel logs. Convert to litres where possible.
- Business travel: Use travel booking records or expense reports. For flights, record origin-destination pairs and class of travel.
- Waste: Check waste contractor invoices or disposal records for volumes and waste types.
When exact data is unavailable, use estimates based on reasonable proxies — floor area, headcount, or industry averages — and flag them clearly as estimates in your inventory. Transparency about data quality is part of good carbon accounting practice.
Step 5: Apply Emission Factors and Calculate
Emission factors convert your activity data into tonnes of CO₂ equivalent. They represent the average emissions generated per unit of activity — per litre of petrol burned, per kWh of electricity consumed, per kilometre flown.
Reliable sources for emission factors include:
- India-specific: Ministry of Environment, Forest & Climate Change (MoEFCC); Central Electricity Authority (CEA) annual CO₂ baseline document
- International: UK Government’s DEFRA emission factor database; GHG Protocol emission factor repository; IPCC default emission factors
The formula is simple:
Emissions (tCO₂e) = Activity Data × Emission Factor
For example: if your office consumes 12,000 kWh of electricity annually and the grid emission factor is 0.82 kg CO₂e/kWh, your Scope 2 emissions are 12,000 × 0.82 = 9,840 kg = 9.84 tCO₂e.
Repeat this calculation for each emission source, then sum by scope. You now have your total annual footprint, broken down by Scope 1, 2, and 3.
Step 6: Review, Document, and Set Your Baseline
Before your inventory is final, review it for completeness and internal consistency. Ask: have I missed any significant emission sources? Are my data sources the most reliable available? Are my estimates reasonable?
Then document everything — not just the final number, but the sources used, the emission factors applied, any assumptions made, and the boundary choices. This documentation is what makes your inventory credible if it is ever verified by a third party or submitted for BRSR (Business Responsibility and Sustainability Reporting) purposes.
This first completed inventory becomes your carbon baseline — the reference point against which all future reductions are measured. It is, in many ways, the most important number your business will produce on its sustainability journey. Solid carbon accounting discipline from this first step forward means every reduction claim you make later will be grounded in data, not aspiration.
Common Pitfalls to Avoid
A few mistakes show up frequently in first-time emissions inventories:
- Scope creep without documentation: Expanding your boundary mid-calculation without noting it makes year-on-year comparison meaningless.
- Using outdated emission factors: Grid emission factors change year to year. Use the factor that corresponds to your reporting year, not a generic published number from years ago.
- Ignoring refrigerants: If your office has air conditioning, refrigerant top-ups (when they happen) can be a surprisingly significant Scope 1 source. Check your maintenance records.
- Skipping the narrative: Numbers without context are hard to act on. Add a short qualitative summary explaining what drives your largest emission categories — this makes the inventory useful as a management document, not just a compliance artifact.
Building your first emissions inventory is the beginning of a much larger conversation — about reduction targets, supply chain responsibility, and what it means for your business to be genuinely net zero rather than simply carbon-neutral on paper. That conversation is worth starting, and this is where it begins.