During the first stages of building design, issues such as local climate, surrounding buildings and orientation are determining factors. The impact of these boundary conditions on daylight illuminances in an open-plan office space is studied in terms of daylight factor, daylight autonomy and useful daylight illuminances. Climate conditions in the location determine the characteristics of the daylight source, such as the ratio between diffuse lighting and global lighting. However, surrounding buildings and elements which may block daylight in the space hold more weight than the orientation of glazed faç ades, but are not always taken into consideration in daylighting studies.

Office buildings consume large amounts of energy and are responsible for large amounts of greenhouse gas emissions worldwide. Among building energy efficiency measures, solar shading plays a significant role in reducing building energy consumption for cooling. This study analysed the influence of solar protection on daylighting of an open-plan office. Climate-based daylight modelling was used to predict such metrics as daylight factor, daylight autonomy and useful daylight illuminances. The results obtained showed that overhangs, and horizontal and vertical louvres have similar behaviours and sidefins have no relevance to indoor daylight conditions. In all cases, it has been proven that excessive obstruction may yield an excessive reduction in a range of illuminances between 500 and 2000 lux, increasing lighting energy consumption.