A well-designed lighting system provides just the right amount of light for its intended application: less lumens yield poor performance, but more lumens represent wasted energy. Like in any building system design, the optimal capacity can only be specified with an adequate calculation procedure. The purpose of lighting calculation is to reach a suitable illuminance level for the intended application. Although there are many lighting design software packages available, DIALux has the advantage of being free while remaining a powerful design tool. DIALux can adapt to a wide range of project conditions, ranging from individual rooms to complete buildings, as well as outdoor locations. The software can also account for daylighting through windows. Architectural files from common formats like DWG (AutoCAD) can be imported, avoiding tedious file conversions. In this workshop, the focus is to explore the DIALux software as an emerging tool for efficient lighting design for buildings, streets, indoor and outdoor locations.