Societal changes in Energy Efficiency of buildings and the crucial challenges of decarbonisation offer significant opportunities for science and research. Member States, businesses, cities and municipalities as well as common citizens are aiming at reduction of their energy consumption and carbon footprint. The topic links energy efficiency and decarbonisation with economic evaluation or management at various levels of governance. The topic is extremely dynamic. Therefore, the specific topic is formulated in collaboration with the PhD candidate in the initial stages of the studies. The topic offers great potential in the design and implementation of scientific and research projects and also publications. In parallel it is a global topic suitable for international cooperation.