It is important to decide the best beneficial lighting system in the space when we design the lighting at first stage. A Worksheet to simplify the evaluation of the economics of the lighting system was developed. And it was applied to a general office room for each lamp and ballast combinations, and to a factory room with a high ceiling for each HID lamp systems. When we design the lighting system using the Worksheet, we can easily evaluate the economics through converting the total cost invested on the lighting system to the present value or the annual cost.