Primary objective of this thesis is to find out energy level of an existing building and investigate the opportunities in order to improve its energy level by retrofitting the envelope and using exergy analysis methods on alternative HVAC systems. To arrive at the objective, an existing building, Izmir Institute of Technology (IZTECH), Faculty of Architecture Block C, has been used as the case study. This building cannot comply with TS-825 standards (Turkish Standard Assessment) and energy efficiency parameters due to the building components and HVAC systems. According to the recorded outdoor climatic conditions, the building was modeled and simulated; and the retrofitting was tried in EDSL-TAS energy simulation software package. Simultaneously, exergy analyses for the situations before and after refurbishments were employed. Different from the most studies in the literature, this thesis carries out the exergy analyses using the dynamic data instead of the steady state ones. By the evaluation of these analyses together, energy level and the climatic comfort of the building have been seriously increased and the building’s loads have been decreased with ratio of 69.42% for heating system and 34.4% for cooling system after retrofitting. In exergy calculations, exergy efficiency of the system ranges between 2-14% with existing HVAC applications, 4-18% with Air Source Heat Pump (ASHP) and 8-21% with Ground Source Heat Pump (GSHP).