Illumination represents one of the main factors that affect energy consumption on a building, this consumption is even more on an office building. This study presents quantitative and qualitative data of the south façade of an open-plan office in Panama of a building that has a system to regulate internal light. To accomplish this, several measurements of illuminance in three different sceneries: evaluating daylight factor, measuring illuminance levels (lx) and illuminance levels with users’ perception. It was concluded that the building requires this system of light control to operate correctly, 75% of the participants describe their workplace as comfortable.