The International Conference on Renewable Energy Sources & Energy Efficiency is organized for the 4th time with great sucess and it is a very important venue of interchange of experiences, transfer of new knowledge and information. The Conference aims at bringing together all the key stakeholders interested in renewables, energy efficiency and conventional fuels: industrial experts, academic researchers, policy makers, regulators etc. The thematic areas of the Conference cover all topics of renewables, energy efficiency in all sectors and conventional fuels.