CLEVER aims to overcome barriers by developing new harmonised GHG emission factors for transport sector (freight & passenger), encompassing uncovered categories, new and conventional fuels and production paths while taking up the full energy lifecycle (Well-To-Wheel/Wake), and providing clearer guides for calculating and accounting emission factors, covering GHG emissions (CO2eq) of the entire transport chain in all modes. CLEVER Framework ensures consistent calculation of new energy carriers, remaining effective as the industry evolves, and emission calculation method for accurate, quantified and accounted emissions, ensuring policy and business relevance. CLEVER applies multi-actor approach, engaging global stakeholders through a co-design, co-creation and co-assessment process. CLEVER reviews existing emission factors derived from global sources, aligned with scientific advances and gaps identification. The Framework is a concise guide, created upon recommended input parameters, fuel/energy specifications and assumptions. It ensures a) understanding and proper application of consequential and attributional methods, b) clear boundaries calculation to avoid biases, aligning data labels and values for consistent emission factors; and c) document how fuel-based emission factors feed into default emission intensities, considering operational parameters and integration in databases. The Framework contains a) new harmonised GHG emission factors; b) common rules for calculating climate impact and c) decision tree based on these rules. This guide helps stakeholders making informed GHG emissions calculations and mitigates conflicting approaches. The Framework undergoes validation in different industrial uses through personalised coaching. For enhancing market uptake regulatory engagement, certification, standardization (ISO14083 review) and training are planned. Greater consistency and reliability of GHG calculation leads to transport decarbonization supporting EU goals.