Near Zero Energy Buildinds: The Way to Develop Future Intelligent Cities

Building Energy Management (BEM) and Energy Savings are leading researchers and scientists towards the creation of future buildings. The determination of equipment characteristics and the development of energy production and energy management methods, will result to the evolution of building appearance and energy balance. Nearly Zero Energy Buildings (NZEB) have become the next goal for engineers, as they are already part of European legislation and they have to be incorporated in our societies until 2030. If there to be future smart grids and intelligent cities, the NZEB concept must be systematically investigated and well developed. Throughout Europe there is a large variety of concepts and voluntary standards for highly energy efficient buildings or even climate neutral buildings: passive house, zero energy, 3-litre, plus energy, Minergie, Effinergie and others. In addition, these definitions refer to different spheres: site energy, source energy, cost or emissions. Moreover, there may be further variations in the requirements of the above standards depending on whether new or existing, residential or non-residential buildings are under consideration. In a nutshell, the views on how Nearly Zero-Energy Buildings should be defined, on which sphere to make the basis, as well as on which means and techniques are adequate, differ greatly. In this paper the existing low-energy building definitions among EU Member States will be reviewed. Aggregation and improvement of the existing concepts is needed in order to align them to the Nearly Zero-Energy Buildings requirements indicated by the Renewable Energy Directive. A number of challenges and their implications for setting a sustainable and practical NZEB are considered. To achieve a practical and suitable definition, related facts and findings need to be seen in a broader societal context and need to be transferred into a practical standard, taking into account financial, legal, technical and environmental aspects .Especially all the requirements for developing a smart grid and an intelligent city will be addressed. Analysing the implications identified above, it becomes obvious that most of them interact or require the consideration of one or several societal aspects. Consequently, the principles for an NZEB definition should be built on the same broad perspectives, should take into account all financial, legal, technical and environmental aspects and should meet the present and future challenges and benefits. The characteristics and basic principles for setting up a proper NZEB definition, addressing the three main reasons and aims for regulating the building sector: reduced energy demand, the use of renewable energy and reduced associated GHG emissions are considered and analyzed