[en] Whereas the assessment of abatement costs of the different decarbonization solutions is crucial for the definition of an efficient climate strategy, these documents report works of a commission which aimed at specifying the meaning of abatement cost, and at defining a methodological framework for the calculation of these abatement costs. The first report presents the concept and calculation methods of social-economic abatement costs: definition of an efficiency indicator which is consistent with the theory of investment (example with hybrid, electric and thermal vehicles), practical implementation, perception of costs within a broader perspective, methodological synthesis and recommendations. The other reports propose examples of abatement costs for different sectors: transports (situation and peculiarities of the sector, replacement of conventional vehicles by low-emission vehicles, fuel decarbonization in the case of biofuels, levers of technological efficiency and behavioural levers), electricity (sector peculiarities, scenarios of assessment of abatement costs, calculation of production costs, of emission reductions and of abatement costs, calculation of the electricity production marginal cost for usage electrification), hydrogen (usages of hydrogen, hydrogen production technologies excluding electrolysis, technical and economic characteristics of electrolysis, analysis of electric power production), housing (situation and objectives, sector specificities, application to housing renovation, cases of office buildings and of heat networks), and cement (present situation, actions to reduce emissions, calcined clays to reduce the need in clinker, carbon capture and sequestration to produce low-carbon clinker)