LED Technology — Prelims Strategy

Prelims Strategy

For lamp comparisons, divide lumens by watts to obtain luminous efficacy. Do not reverse the ratio or infer efficiency from wattage alone. For a surface, use incident lumens divided by area to calculate lux. The lamp's rated output is not necessarily the flux reaching that surface, so read the stated boundary carefully.

Energy calculations require time. A six-watt difference over one thousand hours is six thousand watt-hours, or six kilowatt-hours. The lower lamp's total consumption is different from the saving relative to the other lamp. A monetary result would need a tariff, which should not be invented.

Remember the 2014 blue-LED Nobel milestone without extending it into a claim about invention of every earlier LED. Distinguish semiconductor emission from incandescence, and white spectral appearance from a single wavelength. Finally, source efficacy, luminaire efficacy, colour temperature and colour rendering answer different questions. Colour temperature is not the casing's physical temperature, and efficient LEDs still require management of waste heat.