The worldwide increasing energy consumption is mainly based on fossil fuel which leads to a large number of environmental problems. Indeed, the combustion of fossil fuels releases into the atmosphere different greenhouse gases and harmful pollutants which are responsible for climate change and cause air quality degradation. Moreover, fossil fuel resources are limited and their depletion will happen sooner or later. Governments of the whole world are urged to take relevant measures and policies for energy transition. To support their choices, different decision support approaches have been developed, mainly in industrialized countries. However, these approaches usually lack coherent integration and rely on expensive and often unavailable detailed data, especially in developing countries. This PhD aims at developing alternative methods for the assessment of air quality and energy strategies in the framework of developing countries. The developed methods are implemented in Cuba which seems an excellent test case to design and apply energy strategies for developing countries. The first part of this work deals with methods intended to reliable assess air quality. For this purpose, an air pollution measurement campaign was carried out in Havana. It provided data to implement and improve a pre-existing methodology capable of estimating Cuban vehicle emission factors. Statistical analysis indicated that traffic accounted for around 50% of particular matter concentration levels. Furthermore, vehicles pre-1980s were identified as the most polluting technologies at the street level. This work also demonstrates the usability of an emission inventory designed for air quality simulations. Benchmarking tools developed in the framework of the Forum for Air Quality Modelling in Europe helped to pinpoint differences between global and regional inventories, and identify where efforts should concentrate for improving emission data. This research also sets up simplified algebraic relationships (i.e. so-called Source-Receptor Relationship) capable of predicting the impacts on concentration levels resulting from regional emission abatement strategies, while being more time-efficient than traditional methods. The second part is dedicated to exploring scenarios for a reliable Cuban energy transition. To this end, the energy fluxes between resources, technologies and final demand were computed for the year 2015. A set of scenarios were then designed on the basis of different mixes of energy resources. These scenarios have been compared according to three criteria that seemed the most relevant for the country geopolitical and economic situation: energy security (degree of dependence from energy imports), sustainability of the energy resources and population exposure to harmful pollutants. Overall, the results indicated that energy security and sustainability increase with wind and solar penetration at different rates. A penetration rate of 20% of the demand significantly decreases fossil fuel requirements and imports. Once raised to 50%, Cuba can achieve complete energy independence. The scenario which fulfils 100% of the electricity demands from solar and wind resources shows the maximum of sustainability. Not surprisingly, the penetration of renewables had positive effects on air quality.