The AutoCAD software has two methods of controlling light intensity: photometric and generic. These can be set in the Units dialog box (usually in a template file) or in the Visualize tab > expanded Lights panel > Lighting Units flyout, as shown here:
The Generic option uses default lighting without any lighting units. The International (lux) and American (foot candles) options enable photometric lighting.
This tip is taken from the ASCENT training guide: AutoCAD 2017: 3D Drawing and Modeling - Mixed Units