The paper presents the results of energy performance evaluation of several blocks of the sector 5 and 6 in Bucharest. Energy assessments are made differently after the height of buildings: S + P + 8 E (10E) and S + P + 4 E, depending on the constructive and energetic particularities Technical documentation which was the basis for assessing the energy performance of buildings was the law no.372/13.12.2005, methodology of calculating the energy performance of buildings - Mc 001 / 2006 and the rules for the application of Emergency Ordinance no. 18/2009 (Annex 8).