An Investigation of Daylighting Performance in Sidelit Spaces

The positive influence of daylight on people’s work and well-being has been confirmed in many studies. However, excessive daylight causes discomfort glare, which decreases work productivity, impairs occupants’ vision, and may even cause headaches. Substantial studies explored glare by correlating physical lighting measurements and subjective evaluations. With the development of High Dynamic Range (HDR) image techniques, dynamic changes of daylighting distributions can be effectively captured. Consequently, more studies paired HDR image techniques with subject evaluations to explore glare. However, studies merely relying on field measurements are not only time-consuming and labor-intensive but may also disturb occupants. To address these problems, this dissertation proposed the method of integrating three research tools, HDR image techniques, simulations, and questionnaire surveys, to investigate daylight glare. Using sidelit spaces across five buildings as the example, this dissertation aimed to demonstrate the accuracy of simulation results and the correlations between subject occupant evaluations and physical lighting data derived from both field measurements and simulation results. This dissertation is comprised of three sections. The first section focused on field measurements. Over 200 HDR images across five buildings were taken and analyzed using select visual discomfort metrics. The results showed that daylight glare probability (DGP) outperformed the other visual discomfort metrics in terms of identifying intolerable and imperceptible glare. The second section utilized these HDR images to calibrate four of the five buildings’ Radiance models. The relative RMSE of simulated vertical eye illuminance under both the Perez all-weather sky model and the hybrid photo-radiometer sky model were 23.7% and 21.2%, respectively. The frequencies of accurate glare prediction under both sky models were 93.9% and 95.5%, respectively. The results indicated that Radiance models with precise geometries and material properties can accurately represent the real lighting environments. Finally, the third section paired questionnaire surveys with both the HDR image technique and simulations to investigate daylight qualities within an open-plan office. The study found that taller windows, proximity to windows, and facing towards windows caused severe glare. By removing workstation partitions and arranging seating orientations perpendicular to the windows, the renovated layout design increased occupant satisfaction with their daylighting environments and tolerance for daylight glare. The last section demonstrated the effectiveness of integrating the three tools in lighting studies and the importance of interior layout and furniture designs in terms of daylight glare reduction