Energy audit is an evaluation of energy utilization and identification of energy-saving opportunities in buildings and the use of energy sources. This research was conducted in the lecture building of the Faculty of Islam, Muhammadiyah University of Yogyakarta, electricity consumption that must be used at the University of Muhammadiyah Yogyakarta for the air system and lighting system in the F6 building every year is 116508 kWh, with a cost of Rp. 120,676,656. The energy consumption intensity used in the F6 building of Muhammadiyah University in Yogyakarta is 6.4 kWh / m ^ 2 / month within 1 year, so according to the standard criteria the Electric Energy Consumption Intensity is very efficient. Energy saving opportunities that can be done to achieve a very efficient category of 3377.78 kWh / month and a cost-saving opportunity of Rp. 3,498,637 for the period of one month. Energy savings in building F6 at Muhammadiyah University of Yogyakarta, if you switch to AC inverter and LED light, which is 82792.4 kWh annually. And the costs incurred are Rp. 85,754,712 kWh / year. Muhammadiyah Yogyakarta University can return money capital of around 4.1 years, if a conventional AC is turned into an AC inverter and ordinary lights become LED lights in each room in building F6.