General model of solar water heating system integration in residential building refurbishment-Potential energy savings and environmental impact

The building sector, which accounts for about 40% of total energy consumption in Europe, offers various possibilities for achieving higher energy efficiency by introducing distributed RES. As 20% of total energy consumption in this sector is used for water heating, it follows that 8% of total energy in Europe is consumed for water heating purposes, which provides great opportunities for energy savings. Solar water heating systems (SWHSs) are a suitable technology for renewable energy source (RES) exploitation to be applied in residential building refurbishment that generate both fossil fuel savings and reductions in CO2 emissions. Due to its complexity, SWHS integration requires a comprehensive approach including consideration of the functional and aesthetic, energy performance, and economic and ecological aspects from conceptual design through to design realization. This article defines a general model of SWHS integration in residential building refurbishment. The model is divided into several basic phases in order to facilitate problem-solving and to enable the individual optimization processes for variant design. The phases are systematically analyzed and a proper procedure and/or methods are established to solve them. At the very beginning of the suggested problem-solving procedure, the measures 'Building Potential', (P) over tilde (B), and 'Degree of Feasibility', p(B), are first introduced in order to estimate the suitability of SWHS integration. A Multi-Criteria compromise ranking method, is recommended for a comprehensive evaluation of design variants and for the selection of the optimal SWHS integration Design Variant. The proposed general model is also applied for solving a real problem - namely, the integration of SWHS through the refurbishment of residential buildings in the suburb of "Konjarnik" in Belgrade, Serbia, which is one of the many that were built in Belgrade after the Second World War