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

Directability: Good to great;
HID sources are compact by nature (relative to their light output). Many of these sources are put into lamp shapes similar to halogen sources. The HID arc tube core - where the light is actually
Figure 8.8 Common shapes of high-intensity discharge (HID) lamps
generated - is quite small and so can be effectively focused and directed.
Efficacy: Excellent (70-100 Lumens per watt);
HID covers a
broad array of source types, but all of them have very good efficacies. Sources with good color rendering capabilities like ceramic metal halide have efficacies on the
lower end (70 lumens per watt), but less color-considerate sources like high-pressure sodium have efficacies as high as 120 lumens per watt.
Lamp Life: Good;
HID sources are rated to last anywhere from 10,000 hours to 30,000 hours; anywhere from 10 to 30 years between relamping.
Temperature requirements: none;
HID sources will work equally well in most any temperature condition.
Heat Generated: Relatively little;
HID sources are efficient and don’t create much infra-red radiation, but the large wattages available mean that the little bit can add up to be quite hot. HID lamps also produce a fair amount of UV radiation. HID lamps implement an outer shield to contain this, but lamps should be discarded if this outer glass is ever compromised. HID sources should also be scrutinized if they are to be used to illuminate
Figure 8.9 The working components of light emitting diode (LED) light sources
UV-sensitive materials or products.
Noise Generated: Some;
Larger HID lamps have ballasts that can click and buzz. Even newer, smaller HID sources that use electronic ballasts can have a slight hum. It is safest not to consider HID sources in spaces where extreme quiet is required.
HID sources are undergoing constant refinement. The current generation of HID sources is focused on ceramic metal halide technology, which offers great color- rendering capabilities. These sources are engineered to come in small packages like the PAR lamps, MR lamps, and “T” lamps, usually associated with halogen sources. HID sources are finding their way into hotels, casinos, and retail operations. They still, however, require warm-up time and are rarely ever silent. A working sample of any HID source should be sampled or mocked-up prior to inclusion on a project.
LED SOURCES
LED’s, or Light Emitting Diodes, have truly come of age and are rapidly being refined to replace many previously popular electric light sources. Applications formally the territory of halogen and incandescent sources can now be solved with LED’s. What was once used as the indicator light on home appliances has evolved into a nearly full spectrum source used for Red-Green-
Blue Color mixing capabilities and as a neutral source - both directable and diffuse - for tasks and accents. LED technology is based on electrifying a diode that emits a single wavelength (color) of radiation depending on the compound of the diode. To gain a broader spectral output, these diodes are mated with phosphor technology in the same manner as fluorescent lamps. These diodes are tiny so that in a cluster of many diodes, each diode can have unique optical and color properties. LED source advancements are leading to LED sources that are
larger, more efficient and possess more desirable color rendering properties. LED sources are very heat sensitive and commonly fail due to heat buildup. LED source applications should always be considered for their ability to dissipate heat.