The Elite Software Light Program quickly calculates the number of luminaires required for a desired average level of lighting in a room. Projects with as many as 10,000 rooms can be computed and stored by Light. A large library of photometric data for over 240 luminaires from various manufacturers (Metalux, Abolite, Columbia, Keystone and others) is provided. Light allows multiple luminaire libraries where each may contain up to 10,000 luminaires. Light can read IES photometric data files from all manufacturers so that updating luminaire libraries is easy. Once given the data on each room, Light automatically looks up the coefficient of utilization (CU) values for the luminaire specified and interpolates up to three ways in order to obtain the exact CU value needed. The floor multiplying factor is also properly adjusted when other than a 20% effective floor reflectance is specified. Light level calculations are shown on screen as data is entered for each room.