Ricerc@Sapienza

The energy policy approach is carrying out a long-time renewal process of the electric and in general energy framework. The energy spent in commercial, residential, and institutional buildings is a great amount (in EU is estimated about 40% of total energy consumption and about 90% in high-density urban areas) [1]. The general encouragement of the rational use of energy, also for residential users, introduced the new approach of the nearly zero-energy buildings (NZEBs) by the European energy performance of buildings directive (EPBD) [3]. NZEB means a building that has a very high energy performance, as determined in accordance with Annex I of Directive [3]. The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources, favoring energy from renewable sources produced on-site or nearby. Let us note that the major appliances (both white and brown goods) and other electric loads not fixed (equipment supplied by plugs) are not taken into account in the NZEB qualification. The EPBD requires all new buildings to be NZEBs by the end of 2020 (public buildings must be NZEBs by 2018). A building may reach the NZEB qualification through a complex of efficient technical building systems (TBSs), building automation control system (BACS), and renewable sources, besides a very high energy performance given by envelope insulation and other passive measures [4] . The TBSs that must be provided vary with the type of building, but will generally include a building electric service and power distribution system to serve the loads, a heating, ventilation, and air conditioning (HVAC) system, a domestic hot water (DHW) system, electronic safety and security systems, and a communication system (ICT). The extremely low amount of energy that NZEBs require (energy spent ES2) comes mostly from renewable local sources (energy generated ERES) like: photovoltaic (PV), ground-source heat pumps (GSHP) or thermal solar systems.