The color temperature of a luminaire, expressed in kelvin, does not determine how much light you get, but rather how well you see, how the environment experiences it, and what the neighborhood and nature notice of it.
Most explanations about light color focus on living rooms and restaurants. This page is about outdoors and industry: business parks, ports, terminals, manufacturing, and the surrounding environment. Different considerations apply there, and one of them is legal.
The lower the Kelvin value, the warmer and more orange the light. The higher, the cooler and bluer. It is about the color of the light, not the amount: Kelvin says nothing about lumens or lux, and also nothing about the color reproduction.
Five values occur in practice for outdoor and area lighting; warm white is sometimes listed in datasheets as 2700 K and sometimes as 3000 K. This is what each of them does and where the limit lies.
It is the value at which people can clearly see contrast and detail without experiencing the light as harsh, and where the blue light component remains limited. For most business parks, parking lots, and logistics sites, this is the starting point, and we only deviate from it when there is a reason to do so.
Do not mix color temperatures on a single site or field. It stands out immediately and reads as a malfunction, even if everything is working. When adding or replacing luminaires: request both the color temperature and the color tolerance of what is already installed. That tolerance is expressed in SDCM or MacAdam steps, and determines how much two luminaires with the same specification are allowed to differ in practice.
Near a sports park next to a residential area, a site on the edge of a nature reserve, or a project in or near Natura 2000, color temperature is no longer a matter of taste. Cooler light contains more blue, and blue light scatters more strongly in the atmosphere: that is what makes the light dome above an area larger. For some fauna, including bats and moths, the blue and white part of the spectrum is more disruptive than the amber one.
That is why the amber version is available at 2200 K. It emits virtually no blue light and is used where the area needs to remain dark but some lighting is still required: along the edge of a nature reserve, on paths near water, or in areas with ecological restrictions. For true dark-sky projects, the color temperature can be even lower: 1,700 or 1,800 K, for example at an observatory, in a designated dark-sky area, or where ecological guidelines set a strict limit on the blue component. These two values are available on all DarkLicht products. It is the lowest value we use, and the downside is that colors are then barely distinguishable. We typically supply a dark-sky version in quantities of ten or more.
That a lower color temperature alone is enough. What a luminaire actually does to the environment depends on the full spectrum, the shielding, and the direction in which the light goes. A full cut-off luminaire at 4000 K disturbs the environment less than a poorly shielded 2200 K one.
We perform the ecological assessment. In a protected area, ecological advice is leading, and that comes from an ecologist. We provide the lighting calculation and the spectral data required for this.
The zone table E1 to E4 with the requirements per zone is on the page about area lighting. Everything about light pollution and full cut-off is in the article about light pollution and full cut-off.
Color temperature is a configuration option, not a different luminaire: the same series is available in multiple color temperatures. All DarkLicht products are also available in 1700 K and 1800 K; the dark-sky version is typically available in quantities of ten or more. Please contact us to inquire about other options available for each series, including amber.
If you are hesitating between two values for your own site, request a test luminaire: looking at it for one evening tells you more than a datasheet. For the corresponding pole heights, everything is at lighting poles and high mast lighting, and for application to area lighting.
Color temperature indicates which shade of white the light has; the color rendering index Ra indicates how true-to-life colors appear under it. Two 4000 K luminaires can have very different Ra values. Sports federations and camera requirements are about Ra, not about kelvin.
Colder light is often perceived as brighter, but that is a property of the eye and not of the luminaire. At low light levels, the eye's sensitivity shifts to the blue part of the spectrum, making 5700 K appear brighter than 3000 K with the same lux at low light levels. How much light there is, you measure in lux.
There is a difference in lm/W between color temperatures, but that difference is small compared to the differences between luminaires and optics. Choose the color temperature based on the application and compare the net efficiency per luminaire.
Two luminaires with the same specification of 4000 K can differ visibly. This variation is called SDCM or MacAdam steps. Request this value if you are adding luminaires or replacing them in phases, because that is where the difference becomes visible.
If there is camera surveillance on your premises, or if a vision system reads license plates, container numbers, or labels, requirements come into play that have nothing to do with kelvins but are always mentioned together with them.
For cameras and vision systems, a flicker-free driver is more important than color temperature: flicker that the eye cannot see will still disrupt a recording or measurement. And a camera benefits more from uniform light without blinding hotspots in the image than from a higher Kelvin value.
What the Ra value measures, why sports federations set requirements for it, and why Ra alone is not enough.
Why more lumens does not mean more light on the ground.
The limit values per zone, the rules per European country, and why full cut-off means 0% upwards.
All subjects together are on subsidy and knowledge base.
If you are hesitating between two color temperatures for your own property, request a trial luminaire. Looking at it for one evening says more than ten paragraphs of text.
Kelvin indicates the color temperature: how warm or cool the white light of a luminaire looks. The lower the value, the warmer and yellower; the higher, the cooler and bluer. It is about the tint of the light, not the amount: you measure that in lux.
In most cases 4000 K. That provides good contrast and detailed visibility without the light being perceived as harsh, and the blue component remains limited. If the site borders residential areas, 3000 K is a good intermediate step; if it borders nature, 2200 K comes into consideration.
Where darkness must remain dark yet something is still needed: along the edge of a nature reserve, on paths near water, and for projects with an ecological precondition. Amber emits virtually no blue light, and the blue part of the spectrum is the most disruptive to a portion of the fauna. The flip side is that colors and faces are difficult to distinguish in it.
Yes. For dark-sky projects, we also supply 1700 or 1800 K: at an observatory, in a designated dark area, or where an ecological assessment or the municipality sets a strict limit on the blue component. That is the lowest value we use. The light is then clearly orange and colors are barely distinguishable, so it is a choice you make because keeping the surroundings dark is the requirement and not because it provides more comfortable viewing.
No. What a luminaire actually does to the environment depends on the full spectrum, the shielding, and the direction in which the light goes. A full cut-off luminaire at 4000 K disturbs the environment less than a poorly shielded 2200 K one. Color temperature is one of the four factors, and not the most important one.
Not in lux, but often in perception. At low light levels, the eye's sensitivity shifts to the blue part of the spectrum, making cooler light appear brighter at the same measurement. That is not a reason to choose cooler light: the amount of light you need is determined by a lighting calculation in lux.
Kelvin states the tint of white the light has. CRI, or Ra, indicates how faithfully colors are rendered under that light. Two luminaires of 4000 K can have a very different Ra. For sports federations and camera requirements, it is about Ra: Ra 60 for class II and III, Ra 70 for class I.
In practice 4000 to 5700 K, but more important than the color temperature are the color rendering, uniformity, and a flicker-free driver. Flicker that the eye cannot see does disrupt a recording or a measurement, and a blinding light source in the image costs more than a few hundred Kelvin.
Better not. Different shades of white next to each other immediately stand out and read as a malfunction, even when everything is working. When adding fixtures or replacing them in phases: request the color temperature and color tolerance of what is already installed.
SDCM, also expressed in MacAdam steps, is the tolerance of the colour temperature: how much two luminaires with the same specification are allowed to differ in practice. With a single delivery, this is usually not noticeable; when adding luminaires years later, it is. Request the value if you are working in phases.
LED luminaires can shift slightly in color as they age. How stable that is depends on the LEDs and the thermal design of the luminaire. Ask about this for an installation you want to expand in phases, because the difference will then be visible next to new luminaires.
We will install a trial luminaire on your site so you can see it for yourself instead of reading it on a datasheet. In addition, you will receive a free lighting calculation and a response from an engineer within one business day.
Look up the values for your own luminaire
Every version is listed in one table, with the datasheet and the photometric file per item.
