Introduction: Third Party Assurance of Carbon Calculations

Third-party assurance for carbon emissions is an independent verification process that evaluates the accuracy, completeness, and credibility of an organisation’s reported greenhouse gas (GHG) emissions. 

As businesses and governments increasingly commit to sustainability and climate targets, such assurance provides stakeholders—investors, regulators, and the public—with confidence that emissions data is reliable and aligns with recognised standards. 

This independent validation is crucial not only for building trust and transparency but also for supporting effective climate action, regulatory compliance, and progress toward net-zero goals.

Common standards: 

• ISO 14064: Offers guidance on quantifying, monitoring, reporting, and verifying GHG emissions at the organisational level. It consists of three parts, covering organisational emissions, project-level emissions, and validation and verification of emissions reports.

Example Third Party Assurance Process

1) The organisation provides high-level aggregate total carbon emissions, alongside calculations and evidence of raw data sources. Thrust Carbon recommended files to provide:

• Standard csv for given period

• Assurance csv for material travel modes (i.e. air) for given period

• Latest Methodology Document 

• Assurance CSV Supporting Sample Calculations

2) Assurance teams review calculations, test a sample by recalculating the totals and check a sample of raw source evidence. 

3) Where discrepancies are found, or further information is required to confirm the calculations the assurance team will raise queries. Note: we kindly ask for any queries that require Thrust Carbon input to be collated into an easy to read excel file.

4) Once all the queries have been closed out an assurance certificate will be issued. 

Thrust Carbon understands the importance of third party assurance and aims to provide transparent calculations to ensure the process is streamlined and efficient. Please see the remaining guides in this folder to ensure you are prepared and understand how Thrust Carbon can help. 

Next Steps

• Understand how Thrust Carbon can support you - Thrust Carbon Guide: Third Party Assurance Support
• Prepare your data - Thrust Carbon Guide: Preparing Data for Third Party Assurance
• Download your data and share with assurance teams along with the additional materials available: 
  • Information for Assurance Teams: Data Governance and Due Diligence
  • Thrust Carbon Full Methodology Document
  • Assurance CSV Support Sample Calculations