The interest in light-emitting diodes (LEDs) for illumination applications has been increasing continuously over the last decade due to two key attributes of long lifetime and low energy consumption compared to the conventional incandescent light and compact fluorescent light. Although LEDs are attractive for lighting applications due to the aforementioned advantages, unique technical challenges, such as the extreme sensitivity of luminous output and useful lifetime to LED junction temperature, need to be overcome for their large-scale commercialization. Among various types of lamps recess downlights are the most common luminaire type in new residential construction. Several LED-based luminaires incorporating more than a single LED chip have been developed to provide the required luminous flux of recess downlight while offering the advantage of higher luminaire efficacy (i.e., higher light output using the same power or lower power consumption for the same light output) over conventional luminaires [1].
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