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 Part 1 provides:- input data for the characterization of building - data for the calculation of the energy need for space heating - procedures for in situ data collection