Carbon Footprint Calculation Guide: A Step-by-Step Approach for Companies

In most companies, "we need to calculate our carbon footprint" starts with a customer questionnaire, a question from a bank or a requirement from an export market. The maths of the calculation is simple; the hard part is deciding what goes into it, collecting the data from the right place and choosing the right factor. This guide explains from start to finish how a company operating in Türkiye can calculate its corporate carbon footprint, and points to detailed sub-guides for each source type.

What does a carbon footprint measure?

A carbon footprint is the total greenhouse gas emissions caused by an organisation or a product, expressed in tonnes of CO₂ equivalent (tCO₂e). It covers not only CO₂ but all the Kyoto gases covered by the GHG Protocol Corporate Standard: CO₂, methane (CH₄), nitrous oxide (N₂O), HFCs, PFCs and SF₆. At corporate scale, a regular, documented and repeatable version of this calculation is called a "greenhouse gas inventory". We cover the inventory concept, scopes and boundaries in detail in the greenhouse gas inventory guide cluster.

Corporate vs product carbon footprint

The two terms are often confused, but they answer different questions:

This guide focuses on the corporate footprint. If a customer is asking for product-level data, see our posts what to do when a customer asks for a PCF and PCF or LCA. A well-built corporate inventory is also the data foundation for product calculations.

Scope 1, 2 and 3: which emissions go where?

The GHG Protocol divides emissions into three scopes (Corporate Standard, Chapter 4):

• Scope 1, direct emissions: Emissions from sources the company owns or controls. Fuel combustion in boilers and furnaces, company vehicles, production processes and refrigerant leaks.
• Scope 2, energy indirect emissions: Emissions from the generation of purchased and consumed electricity, steam, heat and cooling.
• Scope 3, other indirect emissions: Emissions that occur in the value chain, outside the company's control. They are divided into 15 categories, such as purchased goods and services, transport, business travel and use of sold products.

You can find the definitions of the scopes in Scope 1, 2 and 3 explained, and the 15 Scope 3 categories in detail in the Scope 3 categories guide.

Examples from sectors in Türkiye

The table below shows typical sources; each company should draw up its own list based on its activities.

We explain how to draw the boundary for each sector, one by one, in our GHG Protocol boundary guides.

The core formula: activity data × emission factor

Whatever the source type, the calculation rests on the same framework:

Emissions (tCO₂e) = Activity data × Emission factor

• Activity data: The quantity of the activity that causes emissions. The Sm³ or kWh of natural gas burned, the litres of diesel bought for vehicles, the MWh of electricity consumed, the tonnes of steel purchased.
• Emission factor: Emissions per unit of activity. For example, tonnes of CO₂e per 1 MWh of electricity consumed.

CO₂e and GWP

To add different gases together, each gas is converted to CO₂ equivalent using its global warming potential (GWP):

Emissions (tCO₂e) = Σ (Gas emissions (t) × GWP)

The GHG Protocol's GWP document dated August 2024 recommends IPCC AR6 as the most up-to-date values. Under AR6, the 100-year GWP values are 1 for CO₂, 27.0 for methane from fuel combustion, 29.8 for fugitive fossil methane and 273 for N₂O. Türkiye's 2024 national inventory, however, uses AR5 values (methane 28, N₂O 265) in line with UN reporting rules. Whichever set you choose, state it in the report and keep it consistent across years.

A short example

A facility burns 100,000 Sm³ of natural gas a year. Using the net calorific value (34.54 MJ/m³) and CO₂ factor (55.4 t/TJ) from Türkiye's national inventory, the factor including CH₄ and N₂O is about 0.0019154 tCO₂e/Sm³:

100,000 Sm³ × 0.0019154 tCO₂e/Sm³ = 191.5 tCO₂e

We show step by step how this factor is derived, how to work with the kWh on the invoice, and the difference between gross and net calorific value in the natural gas emissions calculation guide.

The calculation process, step by step

The GHG Protocol Corporate Standard describes five steps for identifying and calculating emissions: identify the sources, select a calculation approach, collect activity data and choose emission factors, apply calculation tools, and roll up the results to corporate level (Chapter 6, pp. 40-41). In practice, two more decisions come before these.

1. Set the reporting year and the purpose

The inventory is usually prepared for a calendar year. The purpose (a customer request, CDP, an SBTi target, a bank) determines which scopes and what level of detail are needed.

2. Draw the boundary

Which companies, sites and activities will be included in the inventory? One of the operational control, financial control or equity share approaches is chosen and applied to the whole inventory. This decision also determines which scope leased buildings and vehicles fall under. Details are in the organizational and operational boundaries guide.

3. List the sources

For each site, list the fuels, vehicles, processes, cooling systems, purchased energy and relevant Scope 3 categories one by one. A forgotten source is a bigger error than a wrong factor.

4. Collect the data

Assign an owner to each data item and keep a copy of the document. Verification starts from these documents, not from the calculation file.

5. Select emission factors, calculate and total

Factors are selected following the order in the next section. The calculation can be done in a spreadsheet; what matters is that each row shows the activity data, its unit, the factor, the factor's source and year, and the result side by side. Results are totalled by site and by scope.

Choosing emission factors: IPCC, DESNZ and Türkiye's national values

The general rule: start from the most specific and most reliable data and work down to the general.

Some practical notes:

• Electricity: In Türkiye, the factors published by the Ministry of Energy and Natural Resources (ETKB) are used for Scope 2. The latest form covers the 2023 calculation period and was published on 26 December 2025. The same Ministry's "national grid emission factor" form is intended for project-based emission reduction calculations and is not used for Scope 2. Details are in the electricity emissions calculation guide.
• Fuels: Türkiye's national inventory uses country-specific values for some fuels. For example, for 2022: 55.4 t CO₂/TJ for natural gas and 104.79 t CO₂/TJ for lignite (Table 3.7). For fuels of variable quality such as lignite, a supplier analysis is always better than a default.
• Vehicles: The DESNZ set is a practical reference for litre-based factors including CH₄ and N₂O. The biofuel blend ratio needs to be chosen to match the situation in Türkiye; see company vehicle emissions calculation.
• Year and version: Record which year and version each factor belongs to. The DESNZ set is renewed every year; the 2026 set was published in June 2026 and updated to version 1.2 with a minor correction in July 2026.

We discuss the differences between factor sets and which one to choose in which context in our post on emission factor selection.

The most common mistakes

1. Starting the calculation without drawing the boundary. Where leased buildings and vehicles, affiliates and contract manufacturing belong remains unclear and is interpreted differently every year.
2. Mixing up units and energy bases. The kWh on a natural gas invoice is on a gross calorific value basis; IPCC factors are on a net calorific value basis. Multiplying them directly inflates emissions by about 10 percent.
3. The wrong electricity factor. Using the grid factor published for project emission reductions in Scope 2 can raise the result by more than 40 percent.
4. Reporting Scope 2 as a single number. Because YEK-G (Türkiye's renewable energy guarantee of origin) and I-RECs are available in Türkiye, both location-based and market-based results should be reported.
5. Forgetting refrigerants. Refrigerant top-ups in air conditioning and cooling systems can be significant even in small quantities because of their high GWPs.
6. Not stating source and year. An inventory that does not record which factor, which year and which GWP set was used cannot be verified and cannot be repeated the following year.
7. Confusing the invoice period with the calendar year. December consumption arrives on the January invoice; pay attention to meter reading dates.
8. Either skipping Scope 3 entirely or trying to calculate every category to the same depth. First roughly screen the size of each category, then focus on the large ones. Our post on where to start with Scope 3 shows the way.

From calculation to a verified inventory

The difference between a spreadsheet and a reliable inventory is that the method is documented and can be independently checked. The GHG Protocol Corporate Standard requires the inventory to rest on five principles: relevance, completeness, consistency, transparency and accuracy. ISO 14064-1:2018 defines principles and requirements for quantifying and reporting emissions at the organisation level; it also covers requirements for the design, management, reporting and verification of the inventory. ISO reviewed the standard in 2024 and confirmed it. We explain how the two frameworks relate in our post GHG Protocol or ISO 14064.

A verification-ready inventory needs:

• A written rationale for the boundary and control approach
• Activity data, documents and an owner for each source
• A factor library: source, year, version, unit
• The calculation file and a log of changes between years
• A base year and a recalculation policy (base year guide)

We have collected the points a verifier looks at first in our post the first 10 things checked in emissions verification.

Voluntary corporate inventories also need to be kept separate from mandatory facility-level monitoring. The Turkish Emissions Trading System (TR ETS) Regulation dated 27 August 2026 governs the monitoring, reporting and verification of emissions from the activities listed in its Annex 1, and repealed the 2014 Regulation on the Monitoring of Greenhouse Gas Emissions (Sera Gazı Emisyonlarının Takibi Hakkında Yönetmelik). Mandatory monitoring for facilities within this scope is subject to separate rules; details are in the Turkish Emissions Trading System guide. The two exercises feed each other but do not replace each other.

After the calculation: target and roadmap

A carbon footprint is a starting point. The real value emerges when the results are turned into a target and an action plan:

1. Identify the hotspots. Most emissions are usually concentrated in a few sources: a boiler house, a raw material, a transport corridor.
2. Set a science-based target. SBTi validates whether company targets are aligned with the pace of reduction that climate science requires. For the process, see the SBTi target setting step by step guide.
3. Rank the abatement measures. Rank measures such as energy efficiency, fuel switching, electrification, renewable energy procurement and supplier engagement by impact and feasibility. The abatement measures and MACC guide explains the method.
4. Link them to a roadmap. When the target, the investment plan and the annual inventory are tracked in the same table, progress becomes measurable. See the decarbonization roadmap.

Guides in this cluster

• How to calculate natural gas emissions. From Sm³ and kWh on the invoice to tCO₂e, the gross vs net calorific value difference, fuel oil, LPG and coal.
• How to calculate emissions from electricity consumption. ETKB factors, location-based and market-based Scope 2, YEK-G and I-RECs.
• How to calculate the carbon footprint of company vehicles. Fuel-based and distance-based methods, leased vehicles, electric vehicles.

Each guide includes a worked example with every figure shown and a calculator you can try with your own data.

Working with Alalëa

Alalëa builds the corporate carbon footprint of companies in Türkiye in line with the GHG Protocol and ISO 14064-1: setting the boundary, the data map, the factor library, the calculation and verification readiness. For companies that want to move from inventory to target, our SBTi target setting and decarbonization strategy services use the same data foundation. To get started, see our carbon footprint service page or get in touch with us.