Near Zero Energy Buildings (NZEB). The Passive House
By 2021, all new buildings or buildings that are undergoing a major first-level renovation must have near-zero energy needs (Near zero energy building, NZEB).For new public buildings, including schools, the deadline is advanced to 2019. These types of buildings are certified by systems such as CasaClima, PassivHaus and Leed.
According to a survey carried out by the Energy & Strategy Group of the School of Management of the Politecnic of Milano, about 650 / 950 buildings have been built in Italy with high-efficiency NZEB systems. 93% of these buildings are for residential use, almost all in Trentino Alto Adige, Lombardy and Veneto.
Near Zero Energy Buildings. What is the energy efficiency of the buildings?
Energy efficiency improves the performance of any building, be it an office or a private home, from the point of view of energy consumption. In essence, the goal is to increase energy efficiency or to exploit energy in the best possible way.
In 2010, Directive 2010/31 / EU was approved, ie the EPBD (Energy Performing Building Directive), which abolishes the 2002 Directive and introduces a series of new definitions and requirements to deal with technological changes, such as NZEB (Near Zero Energy Building). Member States must ensure that:
a) by 31 December 2020 all newly constructed buildings are nearly zero energy buildings;
b) by 31 December 2018 the new buildings occupied by public bodies and owned by these are nearly zero energy buildings.
What is NZEB?
The NZEB building is a building with very high energy performance, where very low or almost zero energy needs should be covered to a significant extent by energy from renewable sources, including energy from renewable sources produced locally or nearby.
The energy performance of a building means the amount of energy needed to meet the energy needs connected to normal use of the building, including, in particular, the energy used for:
- hot water production;
Energy from renewable sources means energy from non-fossil renewable sources:
- wind energy;
- solar aerothermal;
- landfill gas;
- gases left over from purification processes;
The Passive House
The diagram above shows a summary of the functioning of the passive house, in which the sum of passive heat inputs of solar radiation transmitted from the windows and the heat generated inside the building from everyday life or through the use of household appliances are almost sufficient to compensate for the losses of the building envelope during the cold season.
In the passive house, unconventional systems are installed to supply the required heat, such as solar panels or heat pumps to heat the air in the controlled ventilation system for energy recovery (as shown in the figure).
Here, any traditional heating system can be eliminated if the energy requirement of the house is very low (less than 15 kWh per m² per year). To obtain these results it is necessary to pay particular attention to the design, with the adoption of very high performance thermal insulation on perimeter walls, roofs and glazed surfaces and by adopting controlled ventilation systems with energy recovery.
The European and national regulatory framework
The genesis of EU legislation to guarantee the energy efficiency of buildings dates back to the 1990s. The European Directive SAVE 93/76, of the Council of European Communities approved on September 13, 1993, to limit carbon dioxide emissions is from 1993. The SAVE 93/76 was then adopted in Italy with the DPR 246 of 21/04/1993 and the Law 237 of 22/09/1993.
As far as Italy is concerned, Law No. 10 of 9 January 1991, implementing the National Energy Plan, was the first to regulate the design methods and the management of the building/plants oriented to energy saving. The law provided for satisfying the energy needs of public buildings or buildings used for public use, favoring the use of renewable energy sources, except for technical or economic impediments.
Europe returns to legislate to dictate the guidelines for energy efficiency of buildings, with Directive 2002/91 / EC (officially repealed from 1 February 2012), and with Directive 2009/28 / EC, on “Promotion of the use of energy from renewable sources “. This Directive set binding national targets on the share of renewable energy in energy consumption and in the transport sector to be met by 2020.
Directive 2010/31 / EU has been implemented by Law 90/2013, converted into law (with amendments) the Decree- Law no. 63 of 2013 no 6 3of 2013, and implemented through the Interministerial Decrees 26/06/2015. Since 1 October 2015, therefore, except in some regional cases due to the concurrent legislation determined by the Reform of Title V of the Constitution, the way of making energy efficiency in buildings has radically changed.
Finally, with the legislative decree 4 July 2014, n. 102, which transposes Directive 2012/27 / EU, measures to improve energy efficiency and reduce primary energy consumption by 20% by 2020 have been identified .
The Directive requires Member States to ensure compliance with the minimum energy efficiency requirements for new buildings and existing ones. It is important to certify the energy performance of buildings and to impose periodic checks on boilers and air conditioning systems.