This standard specifies data and procedures for the calculation of the energy performance of buildings relating to space heating and cooling and domestic hot water production.This standard is a national guideline for immediate and univocal application of technical specifications elaborated by CEN to support the Diretive 2002/91/EC "Energy Performance of Buildings"This standard is divided into 3 parts:Part 1 - Determination of building energy need for space heating and cooling Part 2 - Determination of primary energy and system efficiencies for space heating and domestic hot water production.This Part 3 provides data and methods for the determination of: - seasonal average efficiency of the conditioning system- annual specific need of primary energy for space cooling.