Active solar heating systems for energy efficient buildings in Greece: A technical economic and environmental evaluation

The purpose of this study is the technical and economic evaluation of a typical solar space and water heating system, utilized in an 88 m2 detached house that is designed according to the latest Greek Regulation on the Energy Performance of Buildings as a means toward Nearly Zero Energy Buildings (NZEB). The analysis was conducted for each of the four climatic zones designated in the Greek Regulation. A financial analysis was performed and the Net Present Value and the Discounted Payback Period (DPBP) were calculated and correlated with the solar systems collector area and the storage tank volume. Furthermore, the annual avoided emissions from the substituted fossil fuels are estimated for the solar systems considered. The analysis demonstrates that the typical solar space and water heating system can provide a viable solution toward NZEB with solar coverage and DPBP being strongly influenced by the climatic zone of the building and the type of fossil fuel substituted. In all cases the solar system covers at least 45% of the total heating loads while the payback period is as low as 4.5 years with an annual abatement of more than 50 t of CO2 in the worst case scenario.