When you're shopping for light bulbs, compare lumens to be sure you're getting the amount of light, or level of brightness, you want. The Lighting Facts Label will help. This label makes it easy to compare bulb brightness, color, life, and estimated operating cost for the year.
In the past, we bought light bulbs based on how much energy, or watts, they use. But now it makes more sense to buy lights based on how much light they provide.
When you're shopping for light bulbs, think about the brightness you want by comparing lumens instead of watts. A lumen is a measure of the amount of brightness of a lightbulb -- the higher the number of lumens, the brighter the lightbulb.
Lumens measure how much light you are getting from a bulb. More lumens means it's a brighter light; fewer lumens means it's a dimmer light.
Lumens are to light what
Lumens let you buy the amount of light you want. So when buying light bulbs, think lumens, not watts.
The brightness, or lumen levels, of the lights in your home may vary widely, so here's a rule of thumb:
A:
The CRI or R9 is very different than Kelvin. Kelvin is the temperature or color of the light itself, but CRI or R9 will tell us how well that light will reproduce colors when using it. They are independent metrics and are not correlated in anyway.
What does CRI and R9 mean?
A:
CRI (color Rendering index) and R9 (average of R1-R9) reflect how well a light will reproduce colors. Just because a light is white does not mean that colors will show true underneath it. Incandescent and halogen do a good job of color rendering (CRI 95+), where HID sources typically are low color rendering (sub 50 CRI)
CRI is based on the R1 to R8 colors only, also known as the pastel colors. The higher the CRI the better those colors show. CRI is a standard, but in reality there are 15 color bands, these are referred to as R15. Since R10-R15 are generally not an improvement in color reproduction, those are skipped. ( For reference; solid saturated colors are R9-R12 and earth solids are R13 to R14) The big one, however, is R9 because that is red! R9 is one better than CRI because it adds the all important Red spectrum. Thus colors with red in them will show much better in a high R9 score.Here is how CRI, R9 and R15 are calculated. You can see that CRI uses a limited, albeit critical part of the scale. R9, however adds that important Red color which is why its becoming a more preferred metric in lighting. For designers and users anyway, less so for manufacturers as we'll get to below.
What does the R mean in R9? Its based on R0 (CRI or R1-R8 is
Ra) which is the mathematical representation of the colors below. TCS means Test Color Samples based on a standard
TCS01
7,5 R 6/4
Light grayish red
TCS02
5 Y 6/4
Dark grayish yellow
TCS03
5 GY 6/8
Strong yellow green
TCS04
2,5 G 6/6
Moderate yellowish green
TCS05
10 BG 6/4
Light bluish green
TCS06
5 PB 6/8
Light blue
TCS07
2,5 P 6/8
Light violet
TCS08
10 P 6/8
Light reddish purple
TCS09
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4,5 R 4/13Strong red
TCS10
5 Y 8/10
Strong yellow
TCS11
4,5 G 5/8
Strong green
TCS12
3 PB 3/11
Strong blue
TCS13
5 YR 8/4
Light yellowish pink
TCS14
5 GY 4/4
Moderate olive green (leaf)
How is CRI Calculated?
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CRI (color rendering Index) is calculated as a average of R1-R8, known as the pastel color group.
How is R9 Calculated?
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R9 is calculated as a average of R1-R9, which is the pastel color group up to red.
Whether its CRI., R9 or R15 the numbers are an average. So you have to do all well to score very high. Generally incandescent is the benchmark or reference light (black body radiator in the lab, but that's a much longer article) but really the 100 score on an R15 measurement would be perfect. The perfection is also known as sunlight.Here is an example where the CRI would be high, but the low R9 does not tell the whole story.
Now most lighting spectrum charts will generate all the data. In this chart we see the light is about kelvin and 93 CRI, The R9 drops to 75, which is actually excellent because this is a grow light. Grow lights require a full spectrum, known as PAR for best results. Most R9 in general LED is closer to 40-50. To give some perspective, standards such as Title 24 in California, Well building standards and the GSA (government services agency) are requiring only CRI 80+ and R9 of 50+. Shows that LEDs in general have some work to do to get to R9 standards above 70+, and also why the R9 metric is not listed on many lights yet.
What kelvin color should I choose?
A:Color temperature is mostly a matter of preference. In general, most warehouse lighting and outdoor lighting is K, often called bright white as it's a close representation of sunlight. Lighting we often see in residential use is more relaxed settings are usually K-K. Business office lighting is usually around K. Retail lighting is usually K-K and more than often on the cooler side as the cooler color temperatures typically have a slight advantage in lumen output over a warmer color in the exact same wattage. For retail sales, bright is good to show of the products being sold. Again, these are just common uses, some people do prefer to have a K in their home and others may prefer K for LED wall packs on the side of their building. One thing we will mention is that the American Medical Association recommends staying away from light above K as it can be detrimental to human circadian rhythm and affect sleep patterns. Research in this field is still ongoing and there is a lot of conflicting information out there. Some people claim to get headaches from cooler color temperatures, others from warmer color temperatures. Everybody is different so it really comes down to personal preference.
Some municipalities have strict requirements on what color temperatures can be used for certain applications. If you are doing lighting where there is requirements of a certain color temperature, then you will know the options available to you. Otherwise, go with what you are comfortable with or ask for advice from the experts.
I'm still not sure what color to choose, what should I do?
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Get a sample. Buy 1 light so you can hook it up to power and see it in action. If you decide you want to change colors, you'll only have to return 1 light instead of 20. Once you figure out what you are happy with you can buy the full quantity
Get a sample. Buy 1 light so you can hook it up to power and see it in action. If you decide you want to change colors, you'll only have to return 1 light instead of 20. Once you figure out what you are happy with you can buy the full quantity.
Give us a call and speak with one of our lighting experts to help go over your application and we can help guide you to the best option.
Example of a warm colored light. Note the yellow or brownish tint to the color.
Here is a K white light. Note that the K appears true white.
Here is a K tester vs the K. While some consider the K "dirtier" it is easier on the eyes, especially if you working under it for long periods.
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So you can have a K light that produces blue colors very well, even though its a warm colored light, or a K that does red well. These move independently of each other and are based only on the light source itself. There are some ways to cheat colors with any light, but LED especially and so just because a light is K or pure white, does not tell us whether it will reproduce colors well or not. You have to look at each separately.TSC15 Olive Hue
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