A Revolution for Architecture and Photovoltaic's Zero Energy Buildings: A New Opportunity and Challenge for Technology Based Design

The recast of the European Directive 2010/31/EU establishes that starting from the end of 2020, all new buildings will have to be Nearly Zero Energy Buildings According to this directive, 'Nearly ZEB' means a building that has a very low energy yearly energy consumption, which can be achieved by both the highest energy efficiency and by energy from renewable sources, A relevant international effort on the subject of the Net Net ZEBs-Net ZEB meaning that the buildings are connected to an energy infrastructure-is ongoing in the International Energy Agency (IEA), joint Solar Heating and Cooling (SHC) Task 40 and Energy Conservation in Buildings and Community Systems. Net Zero Energy Solar Buildings' both from the theoretical and practical points of view, this new 'energy paradigm'-or the Net ZEB) balance- might be a revolution for architecture and for Photovoltaic's (PV), too.The engineering only research taking into account mainly the energy aspects seems to be not sufficient to ensure the diffusion of ZEB models: in achieving the ZEB target, a major role will be played by architects and designers, who are amongst the main actors of this revolutionary change. More precisely, because the form of our buildings and cities might change radically because of this new energy requirement, the way architects will take up the challenge of designing ZEBs is crucial, as architects are highly responsible of the form of the city and of its symbolic meanings.In a near future, buildings will be designed to need very little energy (passive design strategies for energy efficiency) and to integrate active surfaces (i.e. PV modules) for generating energy. In the future, design has to consider not only the space we use directly but also the space required to provide for electrical and thermal energies from renewable sources: the surface necessary for placing the energy generation devices. This area can be defined as the 'building's energy footprint' . Because the renewable energy generation systems, in contrast to conventional Energy sources, are visible, for the first time in the tradition of architecture, energy can take a 'form' (i.e. shape, colors and features of a PV generator), and architects are responsible for designing this form(s). Photovoltaic's has many potentialities in a ZEB scenario, thanks to its features and enormous decrease in cost. Because of the high energy consumption of the European countries, PV can contribute significantly to the reduction of the primary, conventional energy supply, as well as to the reduction of the CO2 emissions PV seems to be technically the easiest way to obtain the zero energy balance, as the recent, sharp, drop in prices makes it competitive even with active solar thermal collectors and building materials in general.Photovoltaics is able to generate electric energy from the direct conversion of the sunlight; it can power any kind of energy request of the building (thermal and electrical), with the consequence that a ZEB could be theoretically entirely powered by Photovoltaic.