Denmark aims to become independent of fossil fuels by 2050 through renewable energy integration as well as improving the efficiency of energy resources utilization. The building sector is one of the major targets where buildings in Denmark contribute to about 40% of the overall Danish energy consumption, mainly for heating, ventilation and lighting. It is estimated that energy savings of 70-75% could be attained in the Danish building sector by 2050 through the implementation of cost effective and energy efficient measures This paper focuses on evaluating the energy performance under various conditions of a living lab building situated in Vejle, Denmark. An overall energy model for the whole building was developed taking into account the building envelope, construction materials, thermal properties and various building systems and services employed. EnergyPlus was used to model the building and simulate the overall energy performance under Danish regulations and weather conditions. Preliminary validation of the developed model is presented through comparison with real measurements. Based on the data attained, the energy class in which the building lies will be identified. In addition, an analysis of the main factors that influence the energy performance will be conducted, highlighting the possible areas of improvements in the overall energy performance. The building management system installed in the building is regularly updated and optimized, and therefore the development of such holistic energy model for the building is crucial to be directly integrated in the overall management strategy to improve the performance of the energy systems and to test different control and optimization strategies.