Belessiotis obtained his PhD from Aristotle University of Thessaloniki and is currently the Research Director of the Solar and Other Energy Systems laboratory of NCSR “DEMOKRITOS”. His main research areas are Renewable Energy Sources and Energy Conservation, and his interests include the areas of Thermal Engineering, Physical processes and Metrology. He was project coordinator in a large number of competitive research projects funded from external sources and his scientific work is widely published. His scientific work is published in five books, six original contributions in specialized international encyclopedias (ENCYCLOPEDIA OF LIFE SUPPORT SYSTEMS and ENCYCLOPEDIA OF ENERGY) and more than 250 papers are published in international journals, international and national conferences (with review), as well as many specialized studies. He has approximately 2000 citations on this work. His is permanent member of scientific organisations: ISES, EDS, IDA, ASHRAE, ???, HellasLab (national member of EUROLAB). Professor Soteris Kalogirou obtained his PhD and DSc from the University of Glamorgan, UK. For more than 30 years, he has been actively involved in research of solar energy and in flat plate and concentrating collectors, solar water heating, solar steam generating systems, desalination, photovoltaics and absorption cooling in particular. He has many books and book contributions and has published large number papers in international scientific journals and refereed conference proceedings. He is Editor-in-Chief of Renewable Energy and Deputy Editor-in-Chief of Energy, as well as Editorial Board Member of another eleven journals. He is the author of the book Solar Energy Engineering: Processes and Systems and Thermal Solar Desalination, both published by Academic Press of Elsevier. He has been a member of World Renewable Energy Network (WREN), American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE), Institute of Refrigeration (IoR) and International Solar Energy Society (ISES). Emmy Delyannis received her PhD from the Athens University of Technology (AUth) and carried out postgraduate studies at the universities of Lawrence, Kansas, USA, and Karlsruhe, Germany. She was Assistant Professor of Chemical Engineering and Metallurgy at AUth where she taught the subjects of Heating and Chemical Technology. For about 20 years she was the General Secretary of the European Working Group on "Fresh Water from the Sea” and she organized six symposiums for the European Federation of Chemical Engineers. For her contributions in desalination she was honored with the Public Service Award of the Department of the Interior of USA and with the Certificate of Merit of the International & Environmental Association, USA.