For energy conservation and visual comfort in buildings, Daylighting stands as a useful source. In Dhaka city, the indoor spaces of a many residences do not get proper daylight as other buildings surround them from at least 2/3 sides. So, the staircase (if properly designed) can be a good source of natural light during daytime for at least the single-unit residences. The research aims to study the effectiveness of different window conditions and horizontal skylight configurations at the staircase to enhance the daylight condition for the indoor spaces of a single-unit residence. Computer-based software does the Daylight simulation. In the beginning, the model of the case room with a staircase was developed in ECOTECT. The existing lighting condition was analyzed. For generating realistic lighting levels, to validate and crosscheck the ECOTECT results, these models were exported to RADIANCE Synthetic Imaging software. Finally, the performance of different options was evaluated. It is expected that the outcome of this research will help architects and designers to consider the staircase as a lighting device to improve the daylight condition of the indoor spaces of the single-unit residences.