Artificial lighting by using lamps is one of the efforts to increase the power of light that comes from natural lighting in the room, so that activities in the room can run well and comfortably according to the SNI 03-2396-2001 standard. Nowadays, many rooms lightings are turned on when they are used, from morning to evening, regardless of the daylighting conditions. This of course will result in wasteful use of electrical energy for lighting. In addition, there are also many rooms where the placement of lamp is not planned properly, especially in lighting electricity zoning. Dialux Evo is a building performance simulation software that can describe the natural light illuminance in a room under various conditions. The amount of natural light illuminance in the room is strongly influenced by, among other things, sky conditions, space orientation, eaves width, opening area and type of glass. With this simulation, it will be able to see which parts are still lacking in natural lighting and need to add artificial lighting. Thus, the planning of the lamp placement points can be made properly, so that the use of artificial lighting can be reduced and can save the use of electrical energy. The case study to be taken is a classroom on the 6th and 7th floors of the FTSP Building, Universitas Trisakti, Jakarta. Simulations were carried out at 10:00 PM and 02:00 AM assuming the conditions outside were clear sky and overcast with all lamps off. The use of the Dialux Evo simulation can provide an overview of the lighting level in the room and the zoning of the lamp points. By turning off 1 row of rear lights can save electricity costs of Rp. Rp. 32,453.73/day or 16.7%.