Energy analysis is important to analyze energy consumption pattern, monitoring on how the energy used varies with time in the building and how the system element interrelate. In this case study, a preliminary energy audit is done on lighting and airconditioning system. The lighting and airconditioning system consume the highest amount from the total building energy usage. The study was conducted in the Faculty of Mechanical Engineering Building, Universiti Teknikal Malaysia (UTeM) Technology Campus. From the result shows that the air-conditioning system has contributed approximately 48.8% from the total monthly energy usage. The estimation of Building Energy Index (BEI) for the cooling load is 655.19 kWh/m²/year. Meanwhile, the BEI for lighting system is found approximately 150 kWh/m2/year.