The Role of the Building Envelope in Achieving Nearly-zero Energy Buildings (nZEBs)

The 2010 Energy Performance of Buildings Directive (EPBD) requires all new buildings to be nearly-zero energy buildings (nZEBs) by 2020. A strict definition of nZEB is yet to be defined by the legal framework of each European country. However, the basic principles of nZEBs are the reduction of their energy demands to minimum and, subsequently, the coverage of their low energy demands in a great extent by renewable energy sources. This study focuses on the potential reduction of energy demands in a typical Greek residential building. A model building, representative to the average Greek residential building was designed and used as model. The effect of various parameters on the energy demand of the building, such as insulation, openings and shading devices, was investigated and evaluated. The model building was examined in all four climate zones of Greece using dynamic simulation software tools to define the energy demands. The results suggest that the most efficient constructive solutions for every climate zone lay on various combinations of parameters. The right combination for each climate zone can contribute to a significant energy saving that rises up to 30% and reduce the total annual energy demand of the building to less than 50 kWh/m2.