Lighting is a substantial energy consumer, and a major component of the service costs in manybuildings. Lighting renovation was done on the Department of Electrical and CommunicationsEngineering at the Helsinki University of Technology. The lighting in the renovated auditorium wasalmost 40 years old. New lamps with electronic ballast are more energy efficient and the ballast lossesare smaller. Also the optical properties of the new luminiares have been greatly improved. This papershow the results obtained in one auditorium.