Today a working knowledge of daylighting needs to be part of every lighting designer's skill set. But in fact, Daylighting is a broad term that encompasses many methods and techniques. This article explains some of the fundamental principles of daylighting with windows and clerestories, aptly termed Sidelighting, along with a set of important strategies. The concepts presented are applicable to a wide range of project types where daylight enters the building from the perimeter—from the open plan office in a multi-story office tower to the single room classroom.

The first step toward mastering Sidelighting is to realize that it is literally “light from the side.” It is basically a two-part process. The first task is to admit the proper amount of light into the interior by adjusting the size and transmission of the window aperture relative to the room area. The second task is to apply an optimal combination of room-related design decisions to guide and maximize the primarily lateral flow of light away from the window wall, deep into the interior.

Although it sounds simple and straightforward, creating a visually comfortable luminous environment by directing light from one side of a room to the other is an artful challenge. For example, imagine if a lighting designer tried to construct the electric lighting equivalent of a typical window using some type of lensed fluorescent troffer recessed into a wall at eye level. Now consider the apparently conflicting requirements: Occupants viewing computer displays seated anywhere from 2 to 20 feet away from the lighting set-up, who in turn must receive glare-free, adequate illumination, yet also maintain an eye level view of the light fixture. Do not fear, this article will provide at least one or two creative ideas on how to make this lighting condition a more favorable situation.