• LED checklist Here you will find out which features determine the quality of an LED luminaire
    • High-grade LED components
      Components that have been manufactured from high-grade materials with extreme care and great precision are a basic prerequisite for premium LED luminaires. This applies both to individual LED chips as well as to the entire LED module. LED technologies are quite tricky and there are many things that can go wrong.

      Not every LED chip delivers what it promises; looks can be deceptive and incorrect handling can quickly degrade a LED's claimed characteristics. Zumtobel's Quality Assurance operates at two levels: on the one hand, only tested LED chips that meet the brand's exacting requirements are used. The second aspect of our QA is extensive quality testing and careful design and manufacture of LED modules. This underpins tried-and-tested Zumtobel quality that comes with a five-year guarantee.

    • LED-optimised luminaire technology
      Development work at Zumtobel is geared towards meeting the requirements associated with various application areas. Luminous flux, service life, installed load and lighting quality are all decisive criteria. The relationship between luminous flux and installed load is very important. It determines a luminaire's efficiency. A luminaire must incorporate sophisticated thermal management in order to achieve peak efficiency. If the LED chip gets too hot, an LED luminaire's efficiency soon suffers and its warranted characteristics deteriorate.

      Low-quality control gear (drivers) can have similar damaging effects due to unacceptable current spikes. Keeping colour rendering and colour temperature as stable as possible throughout an LED light source's entire service life is a huge challenge. Zumtobel deploys the very latest technologies such as Pi-LED which meets strict criteria that specify a precise colour in MacAdam ellipses. The smaller this deviation, the better the result is.

    • LED checklist
      Features to which you should attach great importance in the case of LED luminaires (depending on the intended purpose):
      • High efficiency, long service life
      • Good colour rendering
      • Stable colour temperature throughout entire service life
      • Sophisticated thermal management – this has a decisive impact on the durability of LEDs. Zumtobel is one of the trailblazers in this area.

  • Colour rendering as a quality criterion for LED luminaires The general colour rendering index (Ra) is an important critical-to-quality feature of any light source. Find out more about colour rendering as a quality criterion for LED luminaires here.
    • How is the Ra value defined?
      The Ra value is defined using the first 8 test colours of the International Commission on Illumination (CIE) and uses just one number to describe colour rendering. This average value only describes colour rendering relative to a reference light source, not other impressions such as naturalness, attractiveness or colour fidelity.

      The International Commission on Illumination is therefore working on a new index and Zumtobel is supplying data obtained from in-house research studies for this work.


    • Zumtobel colour rendering is at least Ra 80
      The general colour rendering index (Ra) is an important critical-to-quality feature of any light source. It is also referred to as the “CRI”. This abbreviation stands for Colour Rendering Index. The maximum Ra of 100 is equivalent to natural sunlight or a halogen incandescent lamp. All Zumtobel LED luminaires offer colour rendering of at least Ra 80.

      Ra 80 means that 80% of colour information is reproduced by the light source, this meets standard requirements for office and industrial applications.



    • Premium LED modules
      Today LED lighting solutions achieve high colour rendering in excess of Ra 90, and hence are more sophisticated than many solutions using fluorescent lamps. Even the colour rendering levels of discharge lamps are achieved, as are other technical lighting properties. For Zumtobel's high-quality products, LEDs produced by various manufacturers are used. In addition, Zumtobel collaborates closely, and in some cases exclusively, with LED and LED module manufacturers, such as Cree, Philips, Osram etc.; this ensures the integration of the latest technologies at an early stage of new product developments. As regards colour rendering of LEDs, the following indications are of key importance: Normative colour rendering in the warmer colour temperature range is usually higher with single-chip LEDs with a blue dye (light-emitting component) and yellow phosphor.

      Colours should be rendered as naturally as possible by choosing the corresponding phosphor mixes. Unfortunately, the efficiency of warm white LEDs is usually lower than that of intermediate and cool white LEDs. For a cooler colour temperature, the phosphor mix is changed. LEDs with cooler light colours are usually more efficient, but their colour rendering index is also lower. By mixing white light through LEDs of different light colours, excellent colour rendering can be achieved with simultaneously high efficiency.

  • Why not simply use LED retrofits? Luminaires are often modernised during the course of refurbishments. Then there is a great temptation to simply replace fluorescent lamps with LED retrofit tubular luminaires. However, currently available retrofit lamps usually fail to meet the requisite photometric requirements. This poses significant safety risks. Click here to read more about this.
    • There are several reasons for these unsatisfactory lighting results:
      • Retrofit lamps do have a lower installed load than fluorescent lamps but their luminous flux is also often significantly lower.
      • The reflector and optics in a Zumtobel luminaire are matched to suit the particular fluorescent lamp that is used. Switching to LED retrofit lamps often results in markedly different distribution characteristics. The stated luminous intensity distribution and the original calculations regarding illuminance and especially glare are no longer valid.
      • As retrofit lamps – when viewed from the side – do not emit light in all directions (360°) the use of luminaires with direct/indirect light distribution is particularly problematic.
      • As tubular retrofit luminaires, unlike fluorescent lamps, are not filled with gas, there is risk of electric shock.
      • As tubular retrofit luminaires are heavier, some of them are not suitable for use in fluorescent lamp fixtures.
      • The stated power consumption of tubular luminaires must be checked because these details are often incorrect.

      Bearing in mind all these technical deficiencies, Zumtobel does not recommend using LED retrofit lamps in its luminaires. We supply » SCUBA, an LED replacement kit, as a convincing alternative for converting existing T16 luminaires to genuine LED luminaires.



Lighting Solution Partners

Greater success due to professional and efficient lighting solutions: Zumtobel provides its partners with information, support and qualifications in dealing with light.
Go to LSP portal


Lighting Competence Program

The Zumtobel partner program for electrical consultants aims at combining their and our competences, thereby exploiting lighting potential and making every-day planning and design work easier.
Go to LCP portal


Lighting Design Program

This Zumtobel partner program has been developed for architects who use light for creative design and want to use first-hand information, support and inspiration for that purpose.
Go to LDP portal
Read more about the programs