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When talking to clients, we’re sometimes confronted with a big,  imaginary question mark in the room: what the heck does this mean for my project?

Terms are often used to explain the benefits of a product – or in reverse: terms are hidden to avoid showing a weakness.

We have therefore asked our engineers to dig deep into the keys and explain their vocabulary to non-lighting specialists. If you miss a term, then please come back to us and let us know: we will extend the definition on a regular basis.

Lumen / Lumen per Watt (lm, lm/W)

The probably most important term, used in Lighting is Lumen, which is in simple terms the measure of the brightness of a luminaire or the total quantity of light, emitted by a source per unit of time. Lumen per Watt (lm/W) is also called efficacy and measures, how well a light source is producing visible light. The light efficiency on the other hand is the unitless ratio of Watt-In to Watt-Out. The Lumen measurement used in the lighting industry is not identical to ANSI Lumen, predominantly used in the projection industry. 

It’s important to understand, that a conventional light bulb cannot be compared with a LED luminaire: for example, a 60 Watt conventional bulb produces about 800 lumens of light – the same amount of lumens can be generated with a 9 Watts LED luminaire. The conventional light has therefore a efficacy 13.3 lm/W, compared to the LED with 88.8 lm/w.

The required lm/W are usually determined during the light design stage of the project by the lighting designer. 



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Color Rendering Index (CRI)

Have you ever noticed that objects look different under artificial lighting than they do under natural lighting? The characteristics of a luminaire can have a major impact on how things are looking like. This is in particular very relevant in stores, restaurants etc, where the eye is heavily involved in the decision making process.

The Color Rendering Index (or CRI) defines how accurate a luminaire can reproduce the color of an object under artificial light on a scale from 0…100 – the perfect reproduction of sunlight would be 100. In simple terms, the higher the CRI, the more vibrant the colors will appear.  It’s important to mention, that the CRI is not the same as the color temperature. But a high CRI is qualifying a good, solid luminaire, irrespective of its color temperature.  

Zoomlux suggest a CRI >70 for Industrial , >80 for interior and >90 for retail applications.


Color Temperature

In simple words, the color temperature is the measure of the lights’ color, measured in Kelvin (K). Baron Kelvin was a British mathematician, mathematical physicist and engineer. Technically spoken, it is the color temperature of the electromagnetic radiation, emitted from an ideal black body. A color temperature over 5000 K is considered cool (bluish), whereas a color temperature between 2700-3000K is considered a warm, appearing yellowish or reddish.

The color temperature is avery relevant lighting design metric, in particular for Human Centric Lighting Applications. 

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Ingres Protection (IP)

Electrical and electronic equipment is facing a functional detoriation and a subsequent shorter life expectancy, if it is penetrated by water and/or dust. In consequence, the equipment must be protected against such exposures, which is directly dependent on the location where the equipment is operated. In the year 1976, the IEC has published the standard IEC/EN 60529 Standard, detailing the IP protection of equipment.

The IP protection of lighting devices, exposed to the Middle East Outdoor conditions or a humid environment is vital with respect to the asset protection. The harsh climate conditions of the Middle East furthermore requires particular protective materials – materials, usually use in the Northern Hemisphere or in South Eastern Countries like China will most of the time not ensure the IP protection of a luminaire over the entire lifecycle.  Zoomlux Lumya has addressed and solved these challenges 

Impact Protection (IK)

Lighting devices are partially also exposed to a harsh operational environment, and the lights need in consequence be protected against mechanical impact.

Impact Protection is normed as EN / IEC 62262, which is not only relevant for the lighting industry, but for any electrical and electronic equipment . The norm is divided into 11 protection levels (IK00 .. IK10), dependent on the impact energy in joules it has to withstand. 

Usually, the IK protection is relevant for outdoor applications (i.e. sports field lighting / street lighting / etc.) or for industrial lighting. Most of the IK lighting devices have also a higher IP rating and partially even a Explosion Proof Class


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Unified Glare Rating (UGR)

People are sometimes facing a level of discomfort / headache when staying in a light setting over a certain period of time.  It might be a glaring issue, caused by the installed light.  The Unified Glare Rating (UGR) predicts the amount of discomfort- causing glare produced by a lighting installation for a fixed set of conditions.   

International standards such as EN12464 recommend maximum UGRs for different situations. UGR<19 is recommended for many office and classroom settings. UGR issues are often caused by a rather cheap lens and can be optimized by either mechanical measures like the application of honeycomb filters or by optimized lenses. Zoomlux Lumya is particularly focusing the optimization of lighting comfort. 

MacAdam Ellipse

Two newly-bought, entirely identical LED lights emit light with a different color temperature or brightness. This problem is known to LED lights and is caused by the tolerances in the materials and LED production.  

The MacAdam’s measurement – named after the scientists David MacAdam – shows that deviations from a ideal value in a 5 step model. The steps, also called SDCM steps (Standard Deviation of Colour Matching) are ranging from 1 SDCM (nearly no visible deviations) to 5 SDCM (strongly visible deviations). 

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Explosion Proof Classes

Explosion-proof lighting fixtures are designed to protect against the ignition of various environmental factors by uncontained sparks. Explosion-proof designs avoids that internal electrical reactions of a light affect external fumes or hazardous materials like oil, gases, chemicals, or other ignitable atmospheric hazards. Explosion-proof requirements are normed by the National Electrical Code (NEC) and grouped into different zones, categorize operating conditions by both the nature of hazardous material present as well as the probability of it being present for a prolonged period. For gases, vapors, and mists, the general breakdown looks like this, as defined in article 505 of the NEC.

Zoomlux Lumya offers a range of certified, explosion proof luminaires, fulfilling the NEC requirements  

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