Energy audit of a school building was carried out to evaluate the effects of the building retrofitting on energy efficiency and carbon footprint. Lighting intensities of the selected areas in the building were measured and thermal images of the building envelope were compared before and after retrofitting. Combustion performance of the boilers was measured and the effects of the insulation on the natural gas consumption were investigated. According to the results, the lighting system renovation decreased the share of lighting in total electricity consumption of the buildings by 53.2% for the recommended lighting intensities in the selected zones. As a result of the lighting system renovation, carbon footprint of the campus decreased 308,715 kgCO(2) per year. Natural gas consumption decreased by 25.3% after building envelope insulation which equals to 137,078 kgCO(2) per year.