A project carbon impact assessment is a methodological process aimed at quantifying, from the design stage, the GHG emissions generated by a project throughout its life cycle, as well as any potential emissions reductions enabled by its implementation. It is part of the broader framework of environmental impact assessments and supports decision-making by integrating climate considerations.

Integrating carbon impact from the design phase helps guide technical choices, promote low-emission options, and anticipate regulatory requirements (such as the European Climate Law 2021/1119/EU, CSRD, etc.). It also improves the project’s social acceptability and can streamline its administrative review.

At the international level, the ISO 14064-2:2019 international standard provides specifications and guidance for quantifying and reporting GHG emissions and reductions at the project level.

Some countries have developed specific methodological frameworks, like France with its ADEME methodological guide (2022) which outlines how to include GHG emissions in environmental impact studies in France.

In line with ISO 14064-2:2019, a project GHG assessment is structured around the following key steps:

Step 1: Define the project and its objectives

• Describe the project and its expected impact on GHG emissions.
• Clarify the GHG objectives (avoidance, reduction, sequestration).
• Identify relevant stakeholders and reporting needs.

Step 2: Establish the baseline scenario

• Define a credible baseline scenario representing what would likely happen in the absence of the project.
• Ensure the scenario reflects realistic technological, economic, and regulatory conditions.
• Use this as a reference point to quantify the project’s additional GHG impact.

Step 3: Define the boundaries and quantification methodology

• Determine organisational, operational, and temporal boundaries.
• Identify relevant gases, sources, and sinks.
• Select a quantification approach: project-specific data, default emission factors, or modeling.
• Use recognised databases such as Ecoinvent.

What is GHG Protocol ?

GHG Protocol is a methodology developed in 2001 which provides guidelines to measure greenhouse gas (GHG) emissions. It exists alongside the French Bilan Carbone® methodology, developed in 2004, which provides guidelines and tools to perform the measures and identify the dependence of an activity, an organisation or a product to fossil energies.

These methods make it possible to take into account all sources of direct and indirect emissions linked to energy, transport, raw materials or also wastes, in order to draw up an action plan to reduce these emissions. In particular, they enable organisations to meet the requirements of the ISO 14064-1 standard.

Why is it essential today ?

Faced with the challenges of global warming, regulations are becoming stricter and consumers are demanding greater transparency. The latest report from the IPCC (Intergovernmental Panel on Climate Change) underlines the urgent need for action to limit global warming to 1.5°C, and stresses the crucial role of businesses and organisations in reducing greenhouse gas emissions. Carrying out a GHG Protocol gives you a better understanding of your ecological impact and helps you identify practical ways to improve.

Step 1: Define the scope of the study and raise team awareness

Before even starting the GHG Protocol, it is essential to involve all the stakeholders in the organisation. This stage enables teams to be made aware of the carbon issues, to define the objectives of the assessment and to identify the necessary resources. A proper scoping exercise guarantees an effective approach that is consistent with the company’s overall strategy.

Step 2: Data collection

Gather all the information you can on your energy consumption, travel, purchasing, production and waste. The more accurate the data, the more reliable the analysis.

Step 3: Use a recognised calculation methodology

Tools such as the GHG Protocol or ADEME’s Bilan Carbone® method can be used to analyse emissions according to three scopes:

• Scope 1: Direct emissions (e.g. fuel combustion, heat production, etc.)
• Scope 2: Indirect emissions linked to the energy consumed
• Scope 3: Indirect upstream and downstream emissions (e.g. transport of goods, product life cycle, etc.)
  

Step 4: Identify reduction targets and levers

Once the diagnosis has been made, an action plan must be drawn up to reduce emissions. This may include:

• Adopting reduction targets validated by the SBTi (Science Based Targets initiative), a reference for climate trajectories aligned with the Paris Agreement
• Optimising the energy efficiency of buildings
• Switching to renewable energies
• Reducing business travel and promoting teleworking
• Eco-design of products

Step 5: Set up a monitoring system

Reducing emissions is a process of continuous improvement. It is essential to regularly monitor progress and adjust actions accordingly. The ACT (Accelerate Climate Transition) method is a recognised approach for assessing the transition of companies towards a low-carbon economy and structuring an effective monitoring process.

Step 6: Declare your results and strategy

Communicating your GHG Protocol is essential to ensure transparency and demonstrate your commitment to the ecological transition. There are a number of organisations that can help you declare your results and assess your low-carbon strategy:

• SBTi (Science Based Targets initiative): Possibility of publicly committing to reduction targets set in accordance with scientific recommendations
• CDP (Carbon Disclosure Project): International platform for reporting on the carbon footprint of companies
• WBA (World Benchmarking Alliance): Ranking of companies according to their commitment to sustainable development

Step 7: Get yourself assessed

A critical review by a certified third party guarantees the quality and credibility of the GHG Protocol. It is recommended that you go through specialist organisations such as:

• ACT Evaluation : Evaluates the climate transition strategy of companies
• Afnor verification: Certification of environmental data and commitments