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;
LED sources are truly on or off, with no warming up time.
Directability: Great;
LED sources are directional by nature, so they can be controlled with lenses and small scale optics. A trickier task is getting LED sources to diffuse evenly, but this too can be accomplished via lenses and diffusing materials.
Efficacy: Good (50-90 Lumens per watt as of this printing);
LED’s undergo so much development that their true efficacy is a moving target and should be confirmed prior to each job. Be mindful of specifying products just because they are LED sources without
confirming the efficacy as LED’s may not always be the most efficacious solution.
Lamp Life: Great
As of this printing, LED source are marketed as having conservative lamp lives in the 50,000 to 80,000 hour range. This translates to 50 to 80 years depending on use. Of note: LED’s tend to “fade away” rather than simply “burn out” so they should be replaced on a schedule rather than on instinct. LED’s are also very heat sensitive. Exposure to excess heat or improper heat dissipation situations can significantly reduce lamp life.
Temperature requirements: Avoid heat
LED sources are commonly mated to significant heat dissipating technology. Care must be taken to allow space for ventilation and heat dissipation (manufacturers may even specify ventilation requirements). Excess heat will significantly reduce the lamp life and reliability of an LED source.
Heat Generated: Relatively little
LED sources convert most input electricity into visible light, but the small amount of heat can add up, akin to fluorescent. Dissipating the heat is critical, regardless of the quantity.
Noise Generated: None
Both LED sources and the electronic components that drive them operate very quietly.
LED’s are everywhere and gaining ground fast. This has resulted in standardized lamp shapes, connection types and more availability. Ubiquity also results in lower costs. LED’s are suitable candidates for directable accent applications, area lighting, and small and medium scale diffuse applications. LED light sources are also useful as continuous linear sources for coves and slots and for colored or color-changing applications. Many suitable LED products are available for retrofitting existing incandescent, halogen and fluorescent installations. It is advisable to take care in researching and sampling LED’s to find products suitable for a project. The major drawbacks are the initial cost and sensitivity to heat as well as the lack of standardization across different brands.
LED’s are available as retrofit lamps, dedicated modules, continuous arrays and
complete luminaires. It is advisable to source LED products from manufacturers with a track-record, who can be relied upon to stand behind the product. It is also
advisable to seek products that follow some form of standardization and have a lamp module that can be replaced without replacing an entire luminaire. Beware of novelty products from mysterious manufacturers and be aware of the hidden inefficiencies of module replacement and disposal.