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

Instant on / off: Yes;
Incandescent filaments heat up to incandescence very rapidly as electricity is applied to them. For our purposes, we will consider it as instant.
Directability: Poor;
Incandescent sources are very large to accommodate the relatively large filament within. Generally, the larger the source, the more inefficient it is to gather up the light and drive it out in a specific direction through the use of optical control. Think of building a reflector around a common “light bulb” to accent a sculpture, and you begin to get the picture.
Efficacy: Very Poor (10 Lumens per Watt);
Incandescent sources do much more to deliver heat than they do light. This results in a large quantity of wasted electricity.
Incandescent sources create about 10 lumens of light for every watt
of electricity put into them.
Lamp Life: Poor;
Another significant drawback of standard incandescent sources is the frequency with which we replace them. Incandescent sources are expected to have a lamp life of about 1000 hours. Using our estimates, this translates to anywhere from three months to one year of regular use before the source “burns out.” As incandescent lamps operate, the metal filament is heated so that is literally boils away.
As the filament boils away, it becomes thin and brittle and,
ultimately breaks, causing failure.
Temperature requirements: None;
Incandescent sources operate equally well in any reasonable temperature condition.
Heat Generated: Lots;
Incandescent sources emit more infra-red radiation than visible light. They are truly heat lamps by nature. They can be exceptionally hot
sources.
to the touch and must be considered for the heat damage thy can do to neighboring materials as well as the additional heating load they represent in the designed space.
Noise Generated: Some;
Incandescent sources have a tendency to “buzz” when they are dimmed down. This generally comes from the filament buzzing due to vibration as electricity flows through. Incandescent sources are fairly silent under full-power operation.
Incandescent lamps are inexpensive to purchase, render colors well, have a pleasing warm color cast, and are easy to dim. They are, however, wildly inefficient, produce a tremendous amount of heat, and are short-lived.
We use incandescent
sources when we are trying to create soft, diffuse, warm floods of light. Incandescent sources are good for distributing an even quantity of warm light in all directions. Occasionally, we build reflectors around incandescent lamps to create downlights and accent luminaires, but the large nature of the source makes them ill-suited for this task. Incandescent lamps are
Figure 8.2 Common shapes of standard incandescent light
often the heart of diffusing luminaires like floor lamps,
table lamps, and decorative sconces. The limit in size and wattage of incandescent sources also limits the size of application. These lamps are usually suited to smaller environments and low (10’-0” and under) ceilings. Considering the scheduled phasing out of incandescent sources and the emergence of suitable alternatives in the form of compact fluorescent and LED technology, there is dwindling justification for specifying incandescent sources on a project.