Bluestone Energy’s Director of Lighting Gabriel Andreson recently wrote an article for EDC Magazine titled “Evaluating LED Technology”, in which he reviews the ways facility managers and other buyers of LED technologies should evaluate the offerings in the marketplace. From the article:
n order to better evaluate LED technology, there are a few key concepts that must be understood:
Luminous Efficacy – This is defined as the number of lumens generated per watt of electricity consumed. The more lumens per watt, the more efficient the LED. Currently, a good baseline efficacy for white LED is between 50 and 55 lumens per watt.
Color Temperature – The days of “cool white” and “warm white” are just about gone. The industry standard has shifted to understanding the color of the light in terms of Kelvin temperature. Somewhat counter-intuitively, the higher the color temperature, the “cooler” the color, while the lower the color temperature, the “warmer” the color. As a rule of thumb, warmer temperatures are closer to the look of incandescent lights, and cooler temperatures are much closer to daylight. Warm-temperature indoor lighting is generally perceived as soft and welcoming, whereas cool-temperature lighting is best suited for outdoor and high-bay fixtures.
Color Rendering Index (CRI) – The CRI indicates how accurately a light source can convey color information in comparison to natural light. The CRI scale is from 1 to 100. A good baseline CRI for LED is 80 or above.
Lumen Depreciation – LED has one primary enemy: heat. LED lamps and fixtures must utilize heat sinks. LED lamps that do not effectively manage heat significantly depreciate or fade before reaching rated life. In addition to fading, a LED lamp or fixture that is not properly managing heat will shift in color temperature, CR and luminous efficacy, and ultimately will fail before reaching rated life.
