In this paper is the first attempt to structure energy management in buildings retrofitted by Energy Service Company to maintain designed energy performance level. The energy performance of multifamily buildings is investigated. More specifically, ex-post energy data of the buildings are analysed to see the dynamics of the energy performance. The analysis is based on a unique dataset that combines data from energy meters and energy monitoring system. The results indicate that multifamily buildings with proper energy management keep designed energy efficiency level meanwhile providing in the energy performance contract guaranteed indoor temperature in space heating season.