This Recommended Practice conveniently gathers the basic data and techniques which help those concerned with the design of buildings and lighting systems understand and appreciate the opportunities and constraints inherent in daylighting. Daylighted buildings offer significant benefits that include visual and thermal comfort, occupant satisfaction, a connection to the outdoor environment, and reduced energy consumption, maintenance costs, and greenhouse gas emissions. Daylighting can result in significant electric lighting reduction in commercial buildings – 40% or more in side-lighted daylight zones and more than 50% is top-lighted daylight zones. The challenges of daylighting include glare, unwanted solar heat gain, the control of electric lighting, shading systems and coordination of the multiple disciplines affecting daylighting performance from initial planning to actual occupancy. In addition RP-5-13 also addresses daylight delivery methods and fenestration properties of various glazing systems, shading techniques, and control strategies. Measurements and daylight performance simulation tools are also described.