The architecture of light: architectural lighting design concepts and techniques. A textbook of procedures and practices for the architect, interior designer and lighting designer pdfdrive com

Chapter 8 Electric Light Sources

At the core of every electric luminaire is the lamp that actually converts electricity into radiant light energy. Since the commercial success of the standard Incandescent lamp in 1879, modern science has developed a number of ways to electrically create light. Each technology has pros and cons that should be understood by the designer interested in making lighting decisions. Just as it is important to understand the priorities and program of the design job, it is necessary to know which light sources are going to serve those priorities. The topic of light source technology has become more complex as technologies have progressed. When we consider how long humans have relied on the sun as the primary source of illumination, it is easy to understand why electric light source selection is so critical and why our visual system struggles with the color rendering, color temperature and glare issues presented by many of our newer, technologically advanced sources.
We will discuss each of these technologies with the intent of
understanding how each performs, and where each should be used or not used. “Lamp” is the proper name for what most people call a “light bulb.” In our discussion we care about vocabulary as much as anything else, so we will refer to our sources as lamps.
Let’s summarize our working knowledge of the different light source
technologies by identifying and discussing the properties that define their suitability for a specific lighting challenge:
Initial Cost: How expensive is this type of source to purchase?
Operating Cost: The expense of providing electricity, maintaining and replacing the source.
Color Rendering Index: CRI (on our scale of 1 to 100.) A representation of “completeness” of visible spectrum provided by the source, and thus how well is will render colors in the designed environment.
Color Temperature: Expressed in degrees Kelvin or Kelvins; indicates the perceived color of the source itself as a product of an imbalanced spectral output. Roughly categorized as warm, neutral or cool