The sustainability of museum lighting is twofold, as not only energy efficiency is required for high quality illumination but control of damage to objects by optical radiation in addition. The conservation of objects, which can be highly responsive to radiation, is as fundamental as the cultural education by the medium of exhibition. The requirements for visual performance and control of object damage are defined according to the categories of responsivity to light (CIE 157:2004). An existing museum building is analysed by measurements as to lighting performance and damage control by radiation. The lighting energy consumption and resulting cooling loads are derived from the monitored data. The results are discussed and proposals for improving the lighting situation in the building, realised 1983, are developed. (C) 2013 Elsevier Ltd. All rights reserved.