Switzerland have adopted ambitious policy targets for renewable energy and energy efficiency. Although diverse range of policy instruments and energy efficiency measures have been adopted, a deeper understanding is required for practical implementation of the measures. The research mainly applied case study-oriented approach. By monitoring the outcome of the selected energy efficiency measures for heating (hydraulic balancing) and ventilation (hybrid ventilation system) system in existing buildings, the thesis measured the actual impact of the applied measures in buildings, assessed the achieved energy efficiency and developed concrete recommendations considering occupant behavior. By assessing the impact of utility-run energy efficiency programs (EEPs) on electricity savings in Switzerland and the United States, the research explores best operational practices that could be adopted in Switzerland. The thesis contributes to establishing practical insights into how to operate and evaluate the impact of EEPs and energy efficiency measures to catalyze a sustainable energy transition in Switzerland.