The Evolving Relationship Of Lighting Brightness, To Power Consumed

With informed good choices, abundant lighting is already a resource available to all, at little cost. Abundant task lighting is crucial to our safety and productivity. Lighting for decor, not wasteful, may be more abundant, interesting and beautiful.

Light, clean air, good potable water and internet broadband are no-cost essentials of a just society in which the potential of every person may be achieved. Of these essentials, "free" light is the nearest to hand, perhaps not corruptible through stupidity and greed. With lighting we are on the verge of considering power draw only as it relates to potential of generation off-grid. Reduced in cost by more than 90% vs. that from dumb incandescent bulbs, we may choose to use light more abundantly, for safety, productivity and better quality of life. The potential is deserving of a global campaign to do away with light bulbs, just as we did with awful CRT computer and television screens. Again, the solution is in durable, flat things. And, let those flat things for awhile include BR30 LED flood bulbs directed from cans, functionally the same as any LED disk downlight.

This post will evolve over several weeks. Please watch it grow. And, know conclusions have already been expressed here over the four or five years largely mis-spent since excellent LED disk downlights became available for home installation. LED lighting will improve global quality of life and productivity, while hugely contributing to saving of grid electrical power used for residential lighting. Only about 10% of the potential has been achieved so far in the USA. Ref: Adoption Report, USDOE, 2017 .

Here are discussions in this blog:

• Brightness Numbers
• LED Downlighting
• Luminance Definitions

Focus please on the word Brightness of the post title. Go with me to the linked Wikipedia article, and find disastrous confusion sowed by the US Federal Trade Commission in the matter of Lamps, the topic here:
The United States Federal Trade Commission (FTC) has assigned an unconventional meaning to brightness when applied to lamps. When appearing on light bulb packages, brightness means luminous flux, while in other contexts it means luminance. Luminous flux is the total amount of light coming from a source, such as a lighting device. Luminance, the original meaning of brightness, is the amount of light per solid angle coming from an area, such as the sky. The table below shows the standard ways of indicating the amount of light.

Today, dictionary.com has
lamp (noun)

1. any of various devices furnishing artificial light, as by electricity or gas.

There can not be a justification by FTC, to imagine and apply only light bulb point sources as lamps. And, of course an LED light bulb is not a point source. An LED bulb hemispherical lens glows to the side with task lighting efficiency of less than 30% of total lumens. About 70% of typical A-type LED bulb illumination is sent from a circuit board parallel with the base; a nasty and dishonest trick when upright in a table lamp or horizontal in a ceiling fixture. A large fraction of emitted light is lost in the thick diffuser. A wasteful device must not be promoted as other than decoration, without offer of purchase incentives.

A cheap and short-lived A-type LED bulb has sideways illumination like that of the old 100 watt incandescent, and is 40% brighter end-on. If used in a table lamp for reading, 40% of power is wasted. 

Here is proof from test stand comparisons .  At left "100 watt" incandescent bulb. At right EcoSmart ICES-003/B LED, 800 lumens, 10 watts, 3000°K. At full power. The EcoSmart is turned 90° to illuminate the screen with cast from glow of the lens hemisphere as it might in a table lamp or horizontal ceiling fixture. The EcoSmart side illumination is about 500 lumens, equal to that of a "100 watt bulb."

At left "100 watt" incandescent bulb. At right EcoSmart ICES-003/B LED, 10 watts, 3000°K. At full power. The EcoSmart is now straight-ahead to the screen and quite superior to a 100 watt bulb, the effect of 800 lumens, not the useful 500 lumens of a 100 watt bulb. Judge that the EcoSmart if placed upright in a table lamp or horizontal in a ceiling fixture is with usefulness ratio 500/800, about 40% energy waste.

We must go back to the correct usage of brightness as luminance, to inform our decisions, as we develop and select luminaires that ever-better, make light a cost-free resource to enrich human activity. Luminance is first a measure of the illumination to our eyes, of tasks at hand. Nearly as important, it is the test of glare as we gaze upon the luminaire. Glare as a nuisance or hazard, is not regulated and not listed in competition for purchases. Lights continually cheapened and glaring, discredit the switch to LEDs for energy conservation. Where best LED lights will serve essentially forever, we can afford that they be built without weak electronics, easy to look at.

Following the FTC mis-direction, we are taught that lumens count, luminous flux in all directions,  is the modern way to compare lighting choices.

Here is an example:
C/Net, Smart Home
Watts vs. lumens: How to choose the right LED light bulb 

Article by Alina Bradford, May 9, 2017

These comparisons are meaningful only for light in antique candle form, as point source illuminating a beam angle of about 320°. Achievable brightness of such old-fashioned bulbs actually can't exceed that of the well-known "100 watt bulb." Wiring that fed a 150 watt bulb was usually destroyed by heat. The table perhaps consciously under-values LED lighting, where LED tricked to look like point-source incandescent and CFL bulbs, has not been offered at more than about 15 watts. All LED luminaires of higher wattage are of other form, as directional flat plates, the natural display from diodes on circuit boards; and do not belong in this table. Disregard as ridiculous, "corn" LED bulbs at the high end of table wattage. Striped light thrown about a room by a corn bulb, is ugly.

About half of point-source light is fully wasted where the purpose is task illumination as in reading. The comparison prevails where something is sought to fill  A-Series light bulbs with their global confusion of sockets, in USA and other countries with 110 volt mains, E26 threaded. 

We have long had point-source lighting that is not dissipated as point-source, confusing a relationship of watts to potential task illumination. Extremely shiny back reflection within a light bulb does the job most simply, forming a downlight from a ceiling whether or not the bulb is recessed, or displayed upon a pendant with or without a decorative shroud. 

Again,  before LED lighting became practical, interim CFL flood or spot bulbs, muddied watts as a measure of brightness, where a mammoth point-source has lots of internal mis-direction and waste. Worst for waste with simple CFL bulbs, is common practice of setting point-source light in cans that hide more than half of the light output.


The wrong teaching is in failing to distinguish lumens count from directional light, most clearly understood where it might be uniform, flat OLED, from wastefully-thrown light of point source bulbs.

From a human perspective, the Sun is a uniformly-bright disk. Brightness within that disk sets the example of other luminance examples, in the table that follows. A luminance value 0.05 lumens/mm2 is evident as a luminaire-design target.

Hereafter let Luminance be a controlling factor in luminaire planning and design. 

Look at luminance numbers for some existing edge light LED examples:
Cooper SLD6: 0.064 lumens/ mm2
Conturrent 4": 0.074
Lithonia WF3: 0.228
Lithonia WF4: 0.124
EiKO 5": 0.059

Try imposing a uniform lens luminance limit of 0.05 lumens/ mm2.

Tabulate lumens and lens diameter at this limit:

Let there be greater lens luminance, to get about 500 lumens from a 4", 100 mm lens diameter.

These are candidate lumens targets for a range of lens and called size-of-light, in inch,  25 mm increments.Let suggestion of luminaire description by a "brightness number", instead be a series of round-number lens sizes. And, let those size numbers not be those of the lens rim outside diameter.

Please look at last, for discipline in luminaire offerings, those volunteered by China factories without global leadership, and by specifiers everywhere, for competition upon reasonable glare numbers. For greatest number of directional lumens with typically 120° beam angle, we will choose uniform-glare OLED, or edge light luminaires with proven effective 90° downward turn of light. 

Where edge light lumens might be proportional to strip diameter and circumference and luminance is then related to square of diameter, LED edge light strips will be intelligently related to square of diameter, rather than to diameter.

Efficacy based on task illumination will easily be with more than 90% reduction from energy cost with LEDs, vs. cost from A-type point source incandescent bulbs. Improvement will not be the 75% reduction imagined with A-type LED bulbs that look like A-type incandescents and fit in any old luminaire. If LED strip edge lights become the production standard, I hope the diode strips will have a salting of phosphor colors, to better resemble sunlight effects in human vision. Notice to a wished manufacturer: Better, with edge-light luminaires employing LEDs on flexible strips, choose RGB diode strips for full-spectrum, tunable white.

This just in 2-7-2018:

Offered at Gordon Electric . But, I can't find these except through email links, among the vast forest of distributor offerings.

Do can light retrofits compete with an edge light surface mount simple future?
All of these Sylvania offerings are with circles of uniform brightness, here presumed 4" diameter.

All of these are too-aggressive cramming of light, unmindful of hurtful glare. Can lights must not be used for more than "65 watt incandescent equivalent." I bet that 16-watt offering runs quite hot, and I won't buy to try. For residential installation, there is no virtue in such large light concentration. In recessing deep within a can to not see the glare, expect that about 20% of the light energy is thrown away.

In support of this post, and for decision upon lighting selection in my own kitchen remodel, I have purchased several candidate LED edge lights. I will look for useful consistencies in arrangements and sizing, not expecting to find exactly what I want. I want  pretty 500 lumens LED edge lights with 4". 100 mm active lens area. Here is that remodel scheme:

Now in March, 2018, I have planned to use fewer lights of larger size. I thought to use available Nicor DLS10, but they are configured only for individual constant current drivers. Choose edge lights that, like all tape LED lighting, are configured for a constant voltage driver. To employ a common driver, luminaires must connect in parallel. I believe that light engine circuit boards are generally wired to want a fixed current.

My kitchen remodel has been lighted so far with only the two lights of Circuit 1, an out of the box Nicor DLS10, and a still-excellent first-generation 6" Glimpse bought in 2012 as Home Depot T91. It is in further circuits that I want innovation, allowed as trial, in my own home.

Switching as follows is fully tested, operating only Circuit 1 with 4-way control.

On a second try, I purchased this as a common driver, with constant voltage output, dimmable:
Mean Well PWM-90-36   Report, with installation instructions.
Buy at DigiKey 

From the instructions, take the wiring illustration.

Now choose the needed dimmer, with assistance at Lutron.
Buy at Bees Lighting .

Lutron DVSTV Instructions 


With this, observe Nicor DLS10 on a remote constant-voltage driver. Draw power through a Kill-A-Watt meter and observe exceptional brightness at dimmer full power.The DLS10 should draw 15 watts without dimming. Instead at full power it draws 28 watts. I think this proves the DLS10, and probably all like luminaires with a coupled external driver, are the feared constant current device, to have shortened life or simply to be fried, on a constant voltage driver. Sellers of drivers have been through this before. I am lucky that my DLS10 may have survived unharmed. I have my answer at last for the driver seller. Already I had lost interest in LED downlight luminaires on circuit boards, because of manufacturer inattention to glare and to dead-bug litter. There is not one such circuit board luminaire on offer now, that I would happily offer to a customer. There is certainly not a winner, flying off store shelves.

I want to move on to our future with LED edge-light luminaires, surface mounted without demand of large ceiling holes, new junction boxes or new can light bodies. I hope I can come up real soon, with means to fill dark spaces in my new kitchen ceiling.


At September 2018, I must at last complete my remodel kitchen lighting. Here is the illumination with only Circuit 1 lights:

Here is my cut-in plan for fifteen more lights generally 500 lumens each, Commercial Electric 74203 . It will come out brighter than 300 Lux. I believe we want always a bit more light as it becomes affordable. Lighting placement in a completed room involves measurements relative to any convenient structure, planned with computer graphics.