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Old 12-21-2022, 01:49 PM
 
Location: Redwood Shores, CA
1,651 posts, read 1,266,077 times
Reputation: 1600

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I need to replace about 500 light bulbs in our building (hallways, staircases, common areas, garages, exterior flood lights, etc). I am studying what light bulbs to buy.

All my life I change light bulbs just by the "watt" number; but I think there are more to it. With this scale of the work I need to optimize my selection. My goal is obviously to maximize brightness while minimizing electricity usage. Cost may be a consideration if there is big difference there.

I see light bulbs come with at least these numbers:

1. Watts that they actually consume
2. Watts-equivalent of the former non-led bulbs
3. Lumens
4. Estimated energy cost per year

Is there a good way to cut to the best choice? Are some of them inter-related (like the bigger the wattage the more lumens?) that can simplify the evaluation?

I previously got some 90-watt equivalent, 10-watt LED flood light bulbs with 900 Lumens daylight color; after installing it I feel they are not as bright as the older 60 watt bulbs. Is it my imagination or is it something else?
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Old 12-21-2022, 02:18 PM
 
Location: Johns Creek, GA
17,403 posts, read 65,528,173 times
Reputation: 23515
Read up on "lumens" and/or versus "Kelvin"- As far as "the eye" is concerned. This maybe where you have some confusion.
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Old 12-21-2022, 02:44 PM
 
Location: Sunnybrook Farm
4,194 posts, read 2,411,711 times
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Lumens is a measure of light output.

Watts are a measure of power consumed to create light output.

Color temperature is a measure of the color of the light emitted.

For generations, we've all compared the watts of incandescent tungsten bulbs, so we have a strong sense that a 20W bulb is dim, a 200W bulb is quite bright, etc. But actually, we should have been comparing lumens all along, because now we have compact fluorescent and LED bulbs, which consume a whole lot less power for the same light output. Now the manufacturers say ”9W LED, equivalent to 60W” which means ”equivalent to 60W conventional incandescent”.

In fact, some years before the compact fluorescents became common, there was a change to many incandescents (I believe it had to do with the nature of the phosphor that lines the bulb) that increased light output per unit of power input, but not as dramatically as the fluorescents and LEDs. So I have a bunch of 29W, ”equivalent to 40W” bulbs, which are still incandescents.

I'm sure that color temperature can affect our perception of how ”bright” a light is, as well.
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Old 12-21-2022, 02:57 PM
 
105,671 posts, read 107,628,943 times
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Lighting can get a bit confusing with all the terms but the bottom line is actually measured in candle power .

Like your driving reflects your actual gas mileage , candle power is the actual light measured at the work area .

Different lamp types emanate their light in different ways . The way many fixtures work is they are designed to reflect a certain amount of light a certain way .

Incandescent lamps are a point source ..all the light emanates from a single point .

Compact fluorescent are linear sources and emanate light all over .

A fixture designed for an incandescent lamp worked terribly with compacts ..the light distribution sucked in the room .

Led has its own characteristics .

So many times just swapping bulbs for equivalent lumens in led don’t work well in all fixtures.

You can end up with shadows between fixtures , glaring light , not bright enough at the work surface, etc .

So the fixtures can play a big roll in how much light actually makes it downward and how much candle power you actually have .

I have had customers do horrible jobs of lighting an area ,simply going by lumens.

Leds can be very directional and can depend on fixtures actually designed for them to get good lighting that is well dispersed….

Leds tend not to disperse light well when just thrown in a generic fixture that took an incandescent lamp .

Most people don’t really care since they are lighting a hall way or simple one lamp application….but things get really tricky when you are lighting a larger space .

I have very sophisticated software that will work out how many fixtures, the spacing , the types of fixtures and the mounting height after entering room characteristics.

A room with white reflective walls is a whole lot different then a room with darker colors

Last edited by mathjak107; 12-21-2022 at 03:15 PM..
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Old 12-21-2022, 02:59 PM
 
5,656 posts, read 3,483,508 times
Reputation: 16299
Quote:
Originally Posted by RobertFisher View Post
I need to replace about 500 light bulbs in our building (hallways, staircases, common areas, garages, exterior flood lights, etc). I am studying what light bulbs to buy.

All my life I change light bulbs just by the "watt" number; but I think there are more to it. With this scale of the work I need to optimize my selection. My goal is obviously to maximize brightness while minimizing electricity usage. Cost may be a consideration if there is big difference there.

I see light bulbs come with at least these numbers:

1. Watts that they actually consume
2. Watts-equivalent of the former non-led bulbs
3. Lumens
4. Estimated energy cost per year

Is there a good way to cut to the best choice? Are some of them inter-related (like the bigger the wattage the more lumens?) that can simplify the evaluation?

I previously got some 90-watt equivalent, 10-watt LED flood light bulbs with 900 Lumens daylight color; after installing it I feel they are not as bright as the older 60 watt bulbs. Is it my imagination or is it something else?
I suggest that you try changing the bulbs in one or two rooms and see how you like them before doing the whole building.

My suggestion would be to go by the wattage number, but increase it about 50% from your present light bulbs. In other words, if the present light bulbs give off 600 Lumens, I would select light bulbs that give off 900 lumens. This would ensure that you have plenty of light while still saving considerably on the electricity used.

Also consider the brightness of the LED bulbs. Personally, I don't like the "daylight" type bulbs. They are too bright. Consider a "medium" brightness bulb which will be easier on the eyes and less stark/drastic in appearance.
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Old 12-21-2022, 03:14 PM
 
105,671 posts, read 107,628,943 times
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Be careful though ..leds can have a whole lot of concentrated glare when you go to high in lumens in fixtures that are just generic ,what we call contractor fixtures . Meaning just a cheap cover or globe over the lamp without being designed specifically for a particular led
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Old 12-21-2022, 05:04 PM
 
Location: East of Seattle since 1992, 615' Elevation, Zone 8b - originally from SF Bay Area
44,057 posts, read 80,100,596 times
Reputation: 56834
You should buy an assortment and put them in one at a time to evaluate the light. With the current crop of LED bulbs there is a variety of options for the light temperature, with 2700-3000k being warm, 4000-5000k being cool. Some are better than others in different places. For large commercial buildings there are consultants that are hired for this.
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Old 12-21-2022, 05:32 PM
 
105,671 posts, read 107,628,943 times
Reputation: 79313
Quote:
Originally Posted by Hemlock140 View Post
You should buy an assortment and put them in one at a time to evaluate the light. With the current crop of LED bulbs there is a variety of options for the light temperature, with 2700-3000k being warm, 4000-5000k being cool. Some are better than others in different places. For large commercial buildings there are consultants that are hired for this.
While I am now retired , the company i worked for did millions in lighting …I sold lighting too but my specialty was motor controls and variable frequency drives….

I did do some large lighting jobs though in quite a few large nyc hospitals like bronx Lebanon hospital , montefiore medical center , and a bunch of others here

5000k seemed to be my most popular color , followed by 6500k.
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Old 12-21-2022, 06:48 PM
 
1,061 posts, read 1,217,525 times
Reputation: 1683
Im in a dark sky community so this may not matter to you..

A few years ago I bought a home entrance LED security light with the motion detector. This light would come on bright and a very cold white. I am guessing a color temperature of maybe 6000K or higher.

I then started to make all my outdoor lighting dark sky compliant so modified the security light do be dark sky compliant which is 800 lumens or less and a color temperature of 3000K or less, 2700K preferable (still LED). I picked 2700K temp. Dark sky also wants a shield over the light so that direct light only shines more than 5 degree below horizonal.

When the original cold bright white security light came on, it had some "authority".

After I changed the security light to dark sky compliant, when the security light came on, it actually became somewhat calming and inviting. Not exactly what you want with a security light LOL but this is what I have.

FYI, dark sky communities like the lower temperature light because longer wavelength (warmer) light scatters less in the atmosphere than shorter wavelength. I understand this is why the sky appears blue.

I would pick either 3000K or 2700K color temp, try 800 lumen
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Old 12-21-2022, 10:02 PM
 
Location: Berkeley Neighborhood, Denver, CO USA
17,665 posts, read 29,540,339 times
Reputation: 33154
For 500 lamps in a commercial building, I would:
1. Educate myself: lumens, CRI, K
2. Hire an expert
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