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Visual and non-visual effects of different spectral power distributions from light sources - light emitting diodes (LED) vs. 3-phosphorus fluorescent tubes

Govén, Tommy and Laike, Thorbjörn LU (2013) CIE Towards a New Century of Light In PROCEEDINGS of CIE Centenary Conference „Towards a New Century of Light“ 1(2).
Abstract
Light influences man both physiological and experiential and different kinds of light sources may have different impact. In a laboratory study the influence of two kinds of light sources, fluorescent tubes and LED on the experience of the surrounding lighting as well as if there were differences in the biological reactions. 42 healthy subjects took part in the study. Two levels of ambient light were used, 100 cd/m2 and 300 cd/m2, from two different light sources, both with 4000 K. Half of the group were exposed to light from fluorescent tubes and the other half from LED. All subjects experienced two lighting levels in a balanced design. The results show that the subjects experienced the ambient light from LED as brighter than light from... (More)
Light influences man both physiological and experiential and different kinds of light sources may have different impact. In a laboratory study the influence of two kinds of light sources, fluorescent tubes and LED on the experience of the surrounding lighting as well as if there were differences in the biological reactions. 42 healthy subjects took part in the study. Two levels of ambient light were used, 100 cd/m2 and 300 cd/m2, from two different light sources, both with 4000 K. Half of the group were exposed to light from fluorescent tubes and the other half from LED. All subjects experienced two lighting levels in a balanced design. The results show that the subjects experienced the ambient light from LED as brighter than light from the fluorescent tubes. Furthermore the lights from LED were experienced as more pleasant

at the lower lighting level.



Lighting quality and energy efficiency will be an essential part in future lighting design. In order to provide lighting quality, ambient lighting plays an important part.

Several studies have shown that ambient lighting affects people positively and is also a necessary part in energy efficient lighting design (Loe, 2003, Govén et al, 2011). This study shows that ambient lighting provided by LED may be more efficient without decreasing lighting quality.

The results indicate that there are differences in the experience of brightness from reflected light from interior surfaces between LED used in this study and T5 tubes. This is due to the differences in the spectral distribution in the shorter wavelengths. This must be considered while evaluating measured photometric data.

Regarding effects on lighting quality, LED was experienced as most positive at 100 cd/m2, then at 300cd/ m2. LED and the T5 tubes was experienced equal in lighting quality.

This imply that levels around 100cd/m2 seems to be the most appropriate ambient light level using LED with a horizontal task illuminance of 500lux (130 cd/m2). However, at higher luminance levels on ambient lighting above 300 cd/m2 there is a risk that LED may be experienced as more glaring than light from T5 tubes.

Our results show an increased positive experience of T5 tubes from 100 cd/m2 to 300 cd/m2 but the experienced quality of LED lighting declined at 300 cd/m2.

Using ambient light in indoor lighting application there may be a possibility to reduce lighting levels in the same way as in outdoor applications using an experienced brightness correction factor between LED another common used light sources. (Less)
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author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
Photometry, Experience, Cortisol, Spectral distribution, Brightness
in
PROCEEDINGS of CIE Centenary Conference „Towards a New Century of Light“
volume
1
issue
2
publisher
CIE, Vienna
conference name
CIE Towards a New Century of Light
language
English
LU publication?
yes
id
5133b7c8-981b-4d0e-a3d3-6907b278799f (old id 4358588)
date added to LUP
2014-03-13 10:06:01
date last changed
2016-04-16 09:02:15
@misc{5133b7c8-981b-4d0e-a3d3-6907b278799f,
  abstract     = {Light influences man both physiological and experiential and different kinds of light sources may have different impact. In a laboratory study the influence of two kinds of light sources, fluorescent tubes and LED on the experience of the surrounding lighting as well as if there were differences in the biological reactions. 42 healthy subjects took part in the study. Two levels of ambient light were used, 100 cd/m2 and 300 cd/m2, from two different light sources, both with 4000 K. Half of the group were exposed to light from fluorescent tubes and the other half from LED. All subjects experienced two lighting levels in a balanced design. The results show that the subjects experienced the ambient light from LED as brighter than light from the fluorescent tubes. Furthermore the lights from LED were experienced as more pleasant<br/><br>
at the lower lighting level.<br/><br>
<br/><br>
Lighting quality and energy efficiency will be an essential part in future lighting design. In order to provide lighting quality, ambient lighting plays an important part.<br/><br>
Several studies have shown that ambient lighting affects people positively and is also a necessary part in energy efficient lighting design (Loe, 2003, Govén et al, 2011). This study shows that ambient lighting provided by LED may be more efficient without decreasing lighting quality.<br/><br>
The results indicate that there are differences in the experience of brightness from reflected light from interior surfaces between LED used in this study and T5 tubes. This is due to the differences in the spectral distribution in the shorter wavelengths. This must be considered while evaluating measured photometric data.<br/><br>
Regarding effects on lighting quality, LED was experienced as most positive at 100 cd/m2, then at 300cd/ m2. LED and the T5 tubes was experienced equal in lighting quality.<br/><br>
This imply that levels around 100cd/m2 seems to be the most appropriate ambient light level using LED with a horizontal task illuminance of 500lux (130 cd/m2). However, at higher luminance levels on ambient lighting above 300 cd/m2 there is a risk that LED may be experienced as more glaring than light from T5 tubes.<br/><br>
Our results show an increased positive experience of T5 tubes from 100 cd/m2 to 300 cd/m2 but the experienced quality of LED lighting declined at 300 cd/m2.<br/><br>
Using ambient light in indoor lighting application there may be a possibility to reduce lighting levels in the same way as in outdoor applications using an experienced brightness correction factor between LED another common used light sources.},
  author       = {Govén, Tommy and Laike, Thorbjörn},
  keyword      = {Photometry,Experience,Cortisol,Spectral distribution,Brightness},
  language     = {eng},
  number       = {2},
  publisher    = {ARRAY(0x90bbfb0)},
  series       = {PROCEEDINGS of CIE Centenary Conference „Towards a New Century of Light“},
  title        = {Visual and non-visual effects of different spectral power distributions from light sources - light emitting diodes (LED) vs. 3-phosphorus fluorescent tubes},
  volume       = {1},
  year         = {2013},
}