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

The General Properties of Light Emitting Diode Sources:
Initial Cost: Very High;
LED sources are the cutting edge of technology, and, as such, they are expensive to buy. Like all things economic, prices have dropped and will grow. continue to do so as volume and popularity
Operating Cost: Cheap
/ moderate;
LED sources are gaining ground as very efficacious means of creating electric light. Pair this with amazing lamp life, and you have a very low operating cost.
The catch is still
the cost of replacement when the product does fail. Because many LED sources are integrated into lamp modules, arrays or nearly complete luminaires, replacement cost and effort are often similar to
Figure 8.10 Common shapes and configurations of light emitting diodes (LED’s).
replacing an entire luminaire.
Color Rendering Index: 70 - 90 (moderate to good);
LED’s have now made the leap to usefulness as neutral sources with good color rendering properties. Generally, costs increase with increased color rendering indices (CRI), but suitable commodity products are increasingly available. LED sources are also commonly used for saturated colors and color mixing applications. LED sources do require careful scrutiny when intended for color critical situations. It is advisable to view a working sample of a particular product before specifying it for a project.
Color Temperature: Variable (Cool to neutral to warm)
LED products claim to provide color temperature from 2800K up to 5000K. To have faith in the color temperature, it is important to actually see samples of LED products before specifying them.
Ballast and Transformer requirements: Yes;
LED sources run at odd voltages, and most require a proprietary transformer (often referred to as a driver) that may be built integral to the source or may need to be remotely mounted in an accessible location.
Dimming: Yes;
LED’s can be dimmed. The dimming properties are generally a product of the driver or transformer technology and must be specified as such from the manufacturer.