How to Measure Your Organisation’s Carbon Footprint: A Practical Guide

 

Nigerian commercial building with a diesel generator, electricity meter and rooftop solar panels, illustrating carbon footprint measurement and energy use.

By Dr Juliana Philip Ndalnamu
Research Tips with Dr. Juliana

Imagine a hotel announcing that it will reduce its carbon footprint by 30% over three years. It sounds ambitious, but can management explain how much greenhouse gas the hotel currently emits? Without a credible baseline, it is difficult to measure progress.

Last week’s Sustainability Monday article explained Scope 1, Scope 2 and Scope 3 emissions. The next step is learning how to estimate them using activity data and emission factors. This guide introduces the basic methods and shows how Nigerian businesses can begin organising their data.

1. What is activity data?

Activity data is a measurable record of an activity that causes greenhouse gas (GHG) emissions. It tells an organisation how much fuel, electricity, material or service it used during a defined reporting period.

• Scope 1 — direct emissions: litres of diesel or petrol burned in generators, boilers or vehicles owned or controlled by the organisation.
• Scope 2 — purchased energy: kilowatt-hours (kWh) of purchased electricity consumed.
• Scope 3 — other value-chain emissions: business travel, waste disposal, purchased goods and services, and third-party transport where these sources fall within the reporting boundary.

Useful records include fuel receipts, electricity bills, generator logs, vehicle records, procurement documents, travel invoices and waste records. The data required depends on the organisation’s boundary and the emissions sources it includes.

2. What is an emission factor?

An emission factor estimates the quantity of greenhouse gases released per unit of activity, for example, kilograms of CO₂ equivalent per litre of fuel or per kWh of electricity.

Select a factor that matches the fuel or activity, units, reporting year and calculation method. Electricity factors are particularly location-dependent because countries have different generation mixes. Prioritise reliable Nigerian data where available. International factors, such as those published by the UK Government, can be useful when a suitable local factor is unavailable, but document the source and limitations rather than describing a foreign factor as Nigeria-specific.

3. The basic carbon-accounting formula

Emissions = Activity data × Emission factor

The units must match. If fuel consumption is recorded in litres, use a factor expressed per litre. If the result is in kilograms of CO₂e, divide by 1,000 to convert it to metric tonnes of CO₂e (tCO₂e).

What does CO₂e mean? Carbon dioxide equivalent provides a common unit for comparing the climate impact of different greenhouse gases. Check which gases and emissions sources a factor includes to avoid omissions or double-counting.

Example A: Diesel used in a generator

Suppose a commercial facility records 15,000 litres of diesel consumed by its generator during a year. For illustration, assume a factor of 2.7055 kg CO₂e per litre, a value used in a UK Government conversion-factor dataset. Before using it in a formal inventory, confirm the exact factors, categories and gases included in the relevant dataset and reporting year.

Calculation:
15,000 litres × 2.7055 kg CO₂e/litre = 40,582.5 kg CO₂e
40,582.5 ÷ 1,000 = 40.58 tCO₂e

This is a worked calculation, not a claim that the factor is definitive for every Nigerian diesel generator. Actual reporting requires a factor appropriate to the fuel, combustion category and inventory method.

Example B: Purchased grid electricity

An office records 85,000 kWh of electricity purchased from its distribution company during the reporting year. Multiply that consumption by the appropriate grid emission factor for Nigeria and the relevant year.

Calculation format:
85,000 kWh × [verified grid factor in kg CO₂e/kWh] = emissions in kg CO₂e.
Divide by 1,000 to express the result in tCO₂e.

Important: Do not use a grid factor simply because it appears in an online article or spreadsheet. Verify its source, year, units and system boundary. If a suitable factor cannot be verified, disclose the data gap and method used; do not present an unverified value as an official Nigerian factor.

4. A practical example: Building a hotel emissions inventory

Consider a 35-room hotel in Lagos preparing an inventory for the previous financial year. Its administrative and engineering teams collect generator fuel receipts, electricity bills, company vehicle records, staff business-travel information and waste collection records.

Scope	Activity	Data to collect	Possible record
Scope 1	Diesel burned in generators	Litres consumed	Fuel receipts and generator logs
Scope 1	Fuel burned in hotel-owned vehicles	Litres by fuel type	Vehicle fuel records
Scope 2	Purchased grid electricity	kWh consumed	Distribution company bills
Scope 3	Business air travel	Passenger distance or suitable travel data	Travel itineraries and invoices
Scope 3	Waste sent for disposal	Mass and disposal route	Waste contractor records

After verifying the activity data, the hotel selects appropriate factors, calculates each source separately and records results in tCO₂e. It should document exclusions and data gaps. Refrigerant leakage from air-conditioning equipment may be a material Scope 1 source for hotels and should be assessed.

The inventory helps management identify significant emissions sources and investigate reduction options. High generator-fuel use, for example, may justify assessing energy efficiency, generator performance and the feasibility of solar-hybrid power. The inventory identifies where to focus; a separate assessment is needed to determine which interventions are practical and cost-effective.

5. Where can organisations find reliable data?

• Greenhouse Gas Protocol: Standards and guidance for defining boundaries, classifying emissions and calculating corporate inventories.
• UK Government greenhouse gas conversion factors: Annual factors for fuels, travel, waste and other activities. Check the year, category and methodology.
• U.S. Environmental Protection Agency Emission Factors Hub: Reference factors for selected calculations, subject to applicability.
• International Energy Agency: Energy statistics and related data that may support electricity-system analysis.
• Ember Data: Open electricity-generation and power-sector data. Check whether a dataset provides the exact factor needed for the intended inventory.

Where possible, use relevant Nigerian government, electricity-sector or other credible country-specific data. If an international factor is necessary, document why it was selected and explain its limitations. Do not substitute another country’s electricity factor for Nigeria’s without a defensible methodological basis.

6. Seven common mistakes to avoid

1. Choosing the wrong factor: Match the factor to the activity, fuel, unit and calculation boundary.
2. Mixing units: One metric tonne equals 1,000 kg.
3. Leaving out important sources: Assess generators, vehicles, refrigerants and relevant value-chain activities.
4. Failing to record assumptions: Identify estimates and explain how they were made.
5. Double-counting: Apply scope definitions and organisational boundaries consistently.
6. Relying uncritically on spending data: Financial estimates can help when physical data are unavailable, but may be less precise and must be documented.
7. Omitting the factor source and year: Record the publication, version, units and method so the calculation can be reviewed.

7. A practical starting checklist

1. Define the facilities, operations, and emissions sources the inventory will cover.
2. Assign responsibility for collecting and checking data.
3. Gather relevant fuel, electricity, travel, procurement and waste records.
4. Select appropriate factors and record their sources, years, units and limitations.
5. Calculate emissions source by source and check units and arithmetic.
6. Document estimates, exclusions, uncertainty and missing information.
7. Consolidate results into a baseline inventory and use it to identify reduction priorities.

Conclusion: Measure first, then reduce

Credible carbon management begins with clear organisational boundaries, reliable activity data, appropriate emission factors, transparent calculations and documented assumptions. Measurement does not reduce emissions by itself, but it provides a defensible baseline for identifying hotspots, setting targets and monitoring progress.

Nigerian businesses can begin with records they already hold: fuel receipts, electricity bills, travel documents and waste records. The key is to use a consistent method, explain limitations and improve data quality over time.

Reflection question: Does your organisation track fuel, electricity and waste systematically or is it still making assumptions about its environmental impact?

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References

Department for Energy Security and Net Zero. (2024). Greenhouse gas reporting: Conversion factors 2024. GOV.UK. https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2024

Greenhouse Gas Protocol. (2004). A corporate accounting and reporting standard (Revised ed.). World Resources Institute and World Business Council for Sustainable Development. https://ghgprotocol.org/corporate-standard

Greenhouse Gas Protocol. (2015). GHG Protocol Scope 2 guidance. World Resources Institute and World Business Council for Sustainable Development. https://ghgprotocol.org/scope-2-guidance

Intergovernmental Panel on Climate Change. (2006). 2006 IPCC guidelines for national greenhouse gas inventories. Institute for Global Environmental Strategies. https://www.ipcc-nggip.iges.or.jp/public/2006gl/

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 Coming Next on Sustainability Monday

Carbon Footprint vs Carbon Intensity: What’s the Difference and Why Does It Matter?

Measuring an organisation’s carbon footprint is an important first step, but is a business with higher total emissions necessarily less environmentally efficient than one with lower emissions?

Next week on Sustainability Monday, we will explore the difference between carbon footprint and carbon intensity, why the distinction matters, and how businesses can use both measures to evaluate their environmental performance and identify opportunities for improvement.

Join us as we continue turning sustainability concepts into practical knowledge for Nigerian businesses and professionals.

Follow Research Tips with Dr Juliana for more evidence-based insights on carbon accounting, climate action and sustainable business practices.