Life cycle costs and environmental life cycle analysis of solar water heaters in Greece Pantelis N. BOTSARIS 1 , Komninos ANGELAKOGLOU 1 , Georgios GAIDAJIS 1 , John A. TSANAKAS 1 1 Democritus University of Thrace, School of Engineering Department of Production Engineering and Management, Faculty of Materials, Processes and Engineering Vas. Sofias 12, University Central Campus, Building I, 67100, Xanthi, Eastern Macedonia & Thrace, Greece panmpots@pme.duth.gr , kangelak@pme.duth.gr , geogai@pme.duth.gr , itsanaka@ee.duth.gr ABSTRACT Usually, the solar water heater (SWH) systems use the sun to heat a fluid, either water or a heat transfer fluid, such as water-glycol antifreeze mixture, in flat collectors generally mounted on the roof of residential or industrial buildings. The heated fluid is then stored in a tank similar to a convectional gas or electric water tank. Some systems use an electronic pump to circulate the fluid through collectors. In this paper, the basics of solar water heaters (SWH) life cycle costs analysis are discussed and the most popular types for Greece are examined. Life cycle costs are formed and the possibilities for reducing them are discussed. Specifically, for the cost analysis, a life cycle approach, in which the various costs are estimated annually, is considered. The analysis is performed in order to obtain the total cost (or life cycle cost) and the life cycle savings of the system. Moreover, the environmental impacts derive from the life cycle of the systems examined are analyzed and assessed with the application of relative software. In order to examine various impact categories such as global warming, ozone layer depletion, ecotoxicity and so forth, the IMPACT2002+ method is applied. In that aspect the life cycle stages, processes and materials that significantly affect the system examined are identified whereas amelioration actions and redesign “hot spots” are further discussed. The fact that both the economical and environmental pillars of sustainability are examined in this study provides a holistic approach regarding different aspects of solar water heaters life cycle. The main aspect that can be concluded is that solar water heater systems are efficient, cost effective and environmental friendly. The reduction of greenhouse gasses is the main advantage of solar energy. Therefore, solar water heater systems should be employed whenever possible in order to achieve a sustainable future. Keywords : solar water heater, life cycle cost analysis (LCCA), IMPACT 2002+ method, renewable energy, sustainability 1. INTRODUCTION It is well known today that solar energy is a viable, clean and sustainable source. Also, it is a fact that most of the houses build today choose solar water heaters, especially in countries like Greece. The main reason is that they are easy to install and inexpensive. Also, the research has shown that in an average household with electric water heater spends about 25% of its home energy costs on heating water. It was found that homes using solar water heaters (SWH) can save as much as 50-85% annually on the electricity bills over the cost of an electric water heater. Depending of the fuel sources the solar water heater can be more economically over the lifetime of the system than heating water with electricity, fuel oil, propane or natural gas (American Solar Energy Society, 2010; Federal Energy Management Program, 2010; Duffie et al., 1980). Solar water heaters do not pollute because they avoid carbon dioxide (CO2), nitrogen oxides (NOx), sulphur dioxide (SO2) and other air pollution and wastes. When a solar water heater replaces an electric water heater, the electricity displaced over 20 years represents more than 50 tons of avoided carbon dioxide emissions (Federal Energy Management Program, 2010). One of the commonest collectors type for water heating (liquid type) is the flat plate collectors type (Figure 1). Flat plate collectors are divided into two main categories, a) liquid collectors and b) air collectors. A flat plate collector is mainly an insulated metal storage tank with either glass or plastic cover, which is called “glazing”. The storage tank is well insulated to reduce thermal loses to the environment and is equipped with heat exchangers for heating the water with auxiliary energy. The auxiliary energy can be either electricity or diesel. In the case where diesel is considered this is used in a