Full spectrum LEDs

Study on the perception of full spectrum LEDs

Paper-Pencil-Test to avoid the influence of displays on the results
© Fraunhofer IBP
To ensure that displays did not influence the results, tests were carried out using paper and pencils.

In cooperation with leading LED manufacturers, the Fraunhofer Institute for Building Physics IBP conducted the first cognitive-psychological study to compare the effects of full-spectrum LEDs and standard LEDs on people. The goals, methods and main findings are briefly summarized in the following. Further studies are planned and - based on the first study - will provide insights into the effects of LEDs on humans and how they are perceived.

Project goals

It is becoming increasingly important for LED manufacturers to understand how people perceive their products as a whole. Fraunhofer IBP evaluated various LEDs to gain insights into full-spectrum LEDs, which purport to provide electrical lighting systems with natural light. This included 

  • a technical comparison of LED and daylight spectra,
  • a literature research on the effect of light spectra on humans and
  • a cognitive psychology study including subjective assessments and performance tests with 83 individuals in an office environment.

In order to evaluate various aspects such as visual comfort, naturalness, color perception, concentration, general glare and sleepiness, full-spectrum LEDs were compared with conventional LEDs.

Current project status

In the study, 6 out of 19 comparisons between full spectrum and standard LEDs showed statistically significant differences.

For instance, when it came to the subjective evaluation of naturalness and comfort, the full-spectrum LEDs produced better results than the standard LEDs. In the performance tests (concentration, gloss assessed with gloss sorting cards, material sorting), the researchers did not identify any short-term effects. The standard LEDs did not perform better than the full-spectrum LEDs in any of the comparisons in the study.

The technical evaluation showed that, up till now, the high complexity and costs involved have severely restricted the use of daylight spectra in architectural lighting systems. With the advent of LED technology, and through the use of full spectrum LEDs, for the first time unrivaled color rendering can be achieved over a wide range of color temperatures. Unlike in the past, it is now possible to imitate daylight in artificial lighting solutions. 

Project partners

  • Nichia (Japan),
  • Seoul Semiconductor (Korea),
  • Toshiba Materials (Japan),
  • LED-Technik GmbH Lumitronix (Germany)
Gloss card sorting
© Fraunhofer IBP
Gloss card sorting test with NCS gloss cards ranging from full matt to full gloss, according to ISO 2813, 60°.
Integration of LEDs in the lab ceiling
© Fraunhofer IBP
The LEDs were integrated into the lab ceiling and regulated with a DMX control unit.