The electricity consumption in the tertiary sector in the EU is still increasing and a further increase is expected of more than 2 % per year during the next 15 years. This sector includes companies and institutions of public and private services with heterogeneous economic and energy-related characteristics. Building managers and decisionmakers are not enough informed about the electricity consumption structure and electricitysaving potentials. Within the EU Intelligent Energy project ELTERTIARY an overview of existing studies showed that the availability of disaggregated data on electricity consumption and its use by purpose (lighting, office equipment, ventilation, air conditioning, etc.) is poor. The methods of determining the types of end-uses are weak; most studies are based on calculations and estimations, only a few on measurement. In addition, many of the results are not published. EL-TERTIARY developed an internet-based methodology for monitoring electricity consumption. It was applied in more than 120 case studies in 12 EU countries. They cover various types of buildings: offices, schools, universities, kindergartens, hotels, supermarkets, and hospitals evaluating more than 900 technical systems. On the background of ongoing activities on EU level, such as directives, research and implementation projects the paper illustrates the concept of EL-TERTIARY, the newly developed methodology for the documentation of building audits and monitoring as well as selected results.