This document shows the proceedings (summary and slide presentations) of the meeting of several subcommittees of the "Comitato Termotecnico Italiano Energia e Ambiente" (CTI) about technical and regulatory aspects of the national transposition of the EPBD, that took place during the 68th National Congress of ATI in Bologna (Italy) on 11 September 2013.
The first presentation by Prof. Vincenzo Corrado (Politecnico di Torino) details the principles on which the minimum performance levels definition and consequently, how the NZEB definition should be based. An analysis has been made to understand what could be the reachable energy performance of a building which is optimal from an economic point of view. First, the buildings types which are representative of the Italian stock have been identified. Next, a series of improvement measures (both on the systems and on the building envelope) have been evaluated and the associated energy and costs savings have been assessed. Finally, an optimal level for all the variables considered (eg . optimal level of thermal transmittance of the envelope components for different climatic zones ) has been identified. The results show that there is no one optimal energy performance, but a range of optimum energy requirements.
The second presentation by Prof. Livio Mazzarella (Politecnico di Milano) focused on the control of temperature and humidity in summer conditions. The calculation of cooling needs, in terms of primary energy, is currently not included in the Italian framework of energy certificates, but will be included with the new decrees implementing the new Law 90 . Great attention should be paid to to this topic as it has an influence on the global energy demand in summer. The calculation of the primary energy for summer air conditioning is currently carried out according to the Italian standard UNI/TS 11300-3 published in 2010. The progress under revision of this standard will include a clearer definition of the types of systems, including their relationship with ventilation systems, more detailed requirments and calculation methods for the air handling units, that will be seen, not as a single unit, but as an assembly of several components.
The third presentation by Ing. Laurent Socal Laurent addresses the building energy balance issue and the calculation of the main energy performance indicators. The topic is currently under discussion in the European context (CEN TC 228). In Italy, the CTI Recommendation 14 already provides a tool for calculating the energy performance of buildings using renewable energy sources. The calculation model has been deliberately kept as flexible as possible to allow the lawmakers to make their own choices without the need to change the algorithm, but only by assigning different values to the coefficients identified. This approach is about to be adopted for the revision of EN 15603. However, some issues still need to be clarified, as, for example, the calculation of the renewable sources share, the boundary of the building (especially in relation to renewable energy sources), the calculation of the exported energy and a way to take into acount the systems that offer a combined generation of several forms of energy.