Energy performance calculation has been required well before requirements by the EPB directive, like in several other European countries. Regulation 10/91 of 1991 and its application decree DPR 412/93 of 1993 first asked for an energy performance calculation and demonstration of minimum energy performance levels to get a building permit. At that time calculation and requirements were limited to heating service in new buildings. Later, requirements for new buildings were extended to other services (domestic hot water, cooling, ventilation, lighting, etc.) and partial energy performance requirements (e.g. maximum U-values and minimum system efficiencies) were introduced when renovating existing buildings.
Energy performance calculation for legal purpose (e.g. to get a building permit and to issue an EPC) shall be done according to the calculation method specified by the regulation. The national regulation always referred to UNI-CTI standards, that is UNI standards developed by CTI (Comitato Termotecnico Italiano, www.cti2000.it), which is the association in charge of standardisation in the HVAC sector.