The effort to reduce the dependence on imported crude oil in Greece, after the oil crises in the '70s, has resulted, among others, in a total installed area of 3.57 million m(2) solar collectors in 2007, making Greece one of the pioneers in the use of domestic solar hot water system (DSHWS) worldwide. In the present work, the contribution of DSHWS to the reduction of conventional energy and greenhouse gases and other air pollutant emissions in Greece from its early years in mid '70s up to now is assessed. DSHWS market penetration, solar system technological changes and development and demographic changes in association with the climatic conditions in all regions of the country have been taken into account in order to calculate energy conservation and emissions reduction. The results show that the conserved energy ranges from 21.27 GW h(el) (0.1% of the domestic sector energy use) in 1978 to 1513 GW h(el) (2.4%) in 2007, resulting in an abatement of CO(2) emissions, which for the year 2000 was 1.67 Mt, exceeding by 76% the objectives of the Greek Program of "Climatic Change", which indicated savings of 0.95 Mt CO(2) for 2000. Moreover DSHWS maximum technical potential is assessed to be about three times the current installed area, showing that they can play an important role in energy end environmental policy of the country. (C) 2009 Elsevier Ltd. All rights reserved.