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Entries in Lumens vs. watts (1)

Friday
Jun282019

Lumens not Watts

LED lighting

Amazing how time flies, isn't it? Since I wrote an item in 2014 on What is the kiloWatt hour, light bulbs based on light-emitting diodes have matured and are now universally available, and sales easily outstrip those pesky CFLs (compact fluorescent lights). They have virtually replaced halogen lights too, which are being made obsolete despite being more efficient than traditional bulbs. The UK vendor CPC listed 1,330 LED bulbs on its web site but only 141 CFLs, so it's obvious which was the market has headed.

The same principles of kWh power consumption costs apply, but LEDs are far more efficient than halogen bulbs, thereby costing even less to run, to the point that running costs become negligible. LED bulbs might have a fraction of the running costs of traditional incandescent bulbs, but they are pricier to buy - and budget-priced ones use the cheapest components which can fail very quickly. So I try to choose reputable branded ones like Osram, Philips or Crompton.

Lumens not Watts

In olden days (before ~ 2017) we chose firebreathing tungsten filament light bulbs based on their wattage. Everyone knew a 60W was general purpose, 40W for smaller light fittings and 100W for larger ones. A 150W bulb was the largest readily available. They were horribly inefficient (< 5%) and therefore made much better room heaters than sources of light.

Today, instead of considering 'wattage', output is described increasingly using Lumens.

For starters, a 42W halogen bulb is equivalent to 55W in 'traditional' light bulb terms and has a light output of typically 630 lumens. A popular 5-6 Watt 470lm LED bulb equates to an 'old' 40W bulb or thereabouts.  A larger 9-10 Watt 800lm LED bulb roughly equals an 'old' 60W bulb or so.

In other words, popular LED bulbs are typically selling as 6 Watt / 470 lumens (old 40 Watts), 9 Watt/ 800 lumens (old 60 Watts) or 14 Watt/ 1500 lumens  (100 Watts).

I found this very helpful guide from Integral LEDs useful.

We'll eventually get used to buying bulbs based on Lumens, not wattage. Doubtless the price will continue to drop and happily, power consumption will be increasingly negligible.

My preferred source of LED bulbs is TLC-Direct who offer great service including some very hard to get LED bulbs as well as plenty of electrical hardware.