With the objective of monitoring and building performance analysis the German research initiative 'Research for Energy Optimized Building (EnOB)' has funded more than 70 buildings so far. The buildings comprise a large variety of new as well as refurbished examples of building types in the residential and commercial sectors. An important feature of all buildings was the integration of energy efficiency technologies into the architectural concept. The focus of this paper is on performance evaluation of nonresidential buildings, mostly office buildings, which are characterized by passive cooling strategies. The monitoring revealed very low total site energy consumptions outperforming the reference values in the German building code by far. First approaches for net zero energy concepts were investigated as well. A thorough analysis showed that the investment costs of energy-efficient buildings were in the same range as the costs of conventional buildings. Surveys in the buildings discovered that high energy efficiency does not necessarily coincide with higher occupant satisfaction. A significant correlation was found between indoor temperature and air quality and the occupants' possibilities to control them individually. (C) 2013 Elsevier B.V. All rights reserved.