Definitions

Junction temperature is the temperature internal to the LED chip. Junction temperature is a critical measure for evaluating an LED lighting product's ability to deliver long life. The U.S. Department of Energy advises: "Heat management and an awareness of the operating environment are critical considerations to the design and application of LED luminaires for general [...]

Efficacy is a term used when the input and output units of measurement differ. In lighting, the light produced in lumens is compared to the electricity input in watts. The resulting measure of performance is expressed in Lumens per Watt. Efficiency is a dimensionless term used when input and output units of measure are the [...]