1. 50 Shades of White
Effects of Tunable White Lighting on Cognitive Performance in the Workplace

2. David Pfund
President, tambient
Stuart Shell, AIA
Project Manager

3. Overview

4. Human spectral sensitivity
Humans can distinguish more than one million different colors.
CIE Color Space

5. Human spectral sensitivity
Humans can distinguish more than one million different colors.
CIE Color Space
400 nm
420 nm
440 nm
460 nm
500 nm
520 nm
560 nm
380 nm
480 nm
540 nm
580 nm
600 nm
620 nm
660 nm
680 nm
640 nm
700 nm
720 nm

6. Chromaticity
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
CIE Color Space
The range (or gamut) of human spectral sensitivity is represented by the CIE 1931 color space.
Each color is identified by coordinates x,y
Colors associated with a single wavelength form the spectrum locus
All other colors and “white” occur when sources or objects radiate multiple wavelengths x

7. Chromaticity Additive color mixing
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
CIE Color Space
Additive color mixing
Colors achieved by combining two colors are defined by a straight line
The relative power of each source defines the resultant color x

8. Chromaticity Additive color mixing
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
CIE Color Space
Additive color mixing
Colors achieved by combining two colors are defined by a straight line
The relative power of each source defines the resultant color x

9. Chromaticity Additive color mixing
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
CIE Color Space
Additive color mixing
Colors achieved by combining two colors are defined by a straight line
The relative power of each source defines the resultant color x

10. Chromaticity Additive color mixing
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
CIE Color Space
Additive color mixing
Colors achieved by combining two colors are defined by a straight line
The relative power of each source defines the resultant color
Three colors combine to form any of the colors in a triangle according to the relative power of each source x

11. Chromaticity
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
Yellowish orange
Reddish orange
Red
Purplish red
Orange pink
Pink
Purplish pink
Reddish purple
Bluish purple
Purplish blue
Blue
Red purple
Greenish blue
Bluegreen
Bluish green
Green
Yellow
Greenish yellow
Yellow green
Yellowish green
Orange
White
CIE Color Space
Radiant sources and objects that appear “colorless” are described as “white.”
The chromaticity of light radiated by a source or object describes its appearance only
Chromaticity does not describe the spectral composition of a light source x

12. Spectral Power Distribution
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
380
420
460
500
540
580
620
660
700
Relative Power nm)
0.5
1.0
1.5
2.0
North sky light
Noon daylight
Noon sunlight
Sunset sky + sunlight
Spectral Power Distribution
y =
x =
Wavelength
CIE Color Space
Spectral power distribution describes the “make-up” of a light source
The sun radiates energy across most of the electromagnetic spectrum including the entire visible spectrum
The chromaticity coordinates for noon daylight* are x,y = ,
* Average midday combined sunlight and skylight in Western/Northern Europe x

13. Spectral Power Distribution
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
380
420
460
500
540
580
620
660
700
Relative Power nm)
0.5
1.0
1.5
2.0
North sky light
Noon daylight
Noon sunlight
Sunset sky + sunlight
Relative Power
0.2
0.4
0.6
0.8
Blue LED
Green LED
Red LED
Spectral Power Distribution
CIE Color Space
You can’t judge a light source by its color x

14. Spectral Power Distribution
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
380
420
460
500
540
580
620
660
700
Relative Power nm)
0.5
1.0
1.5
2.0
Spectral Power Distribution
CIE Color Space
Noon daylight
380
420
460
500
540
580
620
660
700
Relative Power nm)
0.5
1.0
1.5
2.0
Noon sunlight
Noon daylight
Noon daylight
Noon sunlight x

15. Color Temperature
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
380
420
460
500
540
580
620
660
700
Relative Power nm)
0.5
1.0
1.5
2.0
North sky light
Noon daylight
Noon sunlight
Sunset sky + sunlight
Spectral Power Distribution
Planckian locus
CIE Color Space
6500K
380
420
460
500
540
580
620
660
700
Relative Power nm)
0.5
1.0
1.5
2.0
Spectral Power Distribution
Color temperature describes various “shades” of white light
Based on the chromaticity of light radiated by an ideal “black-body radiator” as a function of its temperature
Noon daylight
Noon sunlight
Noon daylight x

16. Planckian Color Temperature
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
Planckian Color Temperature
CIE Color Space
Fir0002/Flagstaffotos
3750 K
Color temperature describes various “shades” of white light
Based on the chromaticity of light radiated by an ideal “black-body radiator” as a function of its temperature
Expressed in Kelvins (example: 3750 K) x

17. Color Temperature
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
Isotemperature Lines
CIE Color Space
3750 K
CCT = 3750 K
Color temperature describes various “shades” of white light
Based on the chromaticity of light radiated by an ideal “black-body radiator” as a function of its temperature
Expressed in Kelvins (example: 3750 K)
Source chromaticities that are not on the Planckian curve are correlated to a color temperature x

18. Color Temperature
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
ANSI White Quadrangles
CIE Color Space
ANSI C color temperature quadrangles define LED-based white light x

19. Color Temperature
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
Noon sunlight
5000K
Noon daylight
6500K
CCT = 6500K
CCT = 5000 K
ANSI White Quadrangles
CIE Color Space
ANSI C color temperature quadrangles define LED-based white light x

20. Tunable white light 2-channel white tuning x
CIE Color Space (Chromaticity)
ANSI White Quadrangles
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
6500 K
White LED
2700 K
Phosphor ‘b’
Phosphor ‘a’
GPD Global
CIE Color Space
2-channel white tuning x

21. Tunable white light 3-channel white tuning x
CIE Color Space (Chromaticity)
ANSI White Quadrangles
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
6500 K
White LED
2700 K
Phosphor ‘b’
Phosphor ‘a’
Phosphor ‘c’
Cool white LED
Blue LED
CIE Color Space
3-channel white tuning x

22. Tunable white light 5-channel white tuning x
CIE Color Space (Chromaticity)
ANSI White Quadrangles
490 nm
480 nm
470 nm
460 nm
450 nm
380 nm
500 nm
510 nm
520 nm
530 nm
540 nm
550 nm
560 nm
570 nm
580 nm
590 nm
600 nm
610 nm
620 nm
630 nm
650 nm
770 nm
Phosphor ‘a’
Phosphor ‘b’
Phosphor ‘c’
Blue LED
Red LED
Green LED
Green
Red
Blue
White ‘a’
White ‘b’
CIE Color Space
5-channel white tuning x

23. Light and well-being Making light meaningful
Photopigments convert EM radiation to meaningful signals
J. Carroll G.H. Jacobs, in The Senses: A Comprehensive Reference, 2008

24. Light and well-being Light is basic to human physiology
Photoperiod is linked to seasonal changes
Immune and reproductive functions are impacted by light exposure
Sunlight plays a role in Vitamin D production
Light exposure effects mood
Effect may be less pronounced since the industrial era
Hamsters and Long vs. Short Photoperiod
Study of inflammation response by Ashley et al. (2013).

25. Light and well-being
Daily circadian entrainment is necessary for well-being
Morning daylight is most effective in maintaining a 24 hour wake/sleep cycle
Too much light late in the day and especially at night can be a major disruptor
Photoperiod is linked to seasonal changes
Circadian disruption has been associated with poor sleep, increased anxiety and depression, Type 2 diabetes, and higher incidence of breast cancer

26. Light and well-being
Melatonin is a well known marker of the circadian clock
Melatonin production is triggered by darkness and inhibited by light
Retinal melanopsin (peak activity at 460 nm) plays a key role in suppressing melatonin
It is often recommended that we seek exposure to “blue” light during the day and avoid “blue” light at night

27. WELL Building Standard
Based on occupant health, not energy
Incorporates performance verification in the field
Has popularized research on circadian lighting

28. WELL Building Standard
Feature 54: Circadian Lighting Design
Emphasizes equivalent melanopic lux (EML) over other metrics
Sets prerequisites based on illuminance at the eye – not horizontal plane
200 EML from daylight or 150 EML from electric light

29. Circadian phototransduction
Intrinsically photosensitive retinal ganglion cells are principally responsible for our non-visual response to light
They contain melanopsin with peak spectral sensitivity at nm
They receive information from our photopic receptors (rods and cones) via the bipolar cells
They send non-image forming information to the SCN (biological clock)
Life: The Science of Biology, 8th Edition, Sinauer Associates, Inc. and W. H. Freeman & Co., 2007
Photoreception
Phototransduction

30. Designing for circadian effect
Industry efforts to qualify and quantify the biological effects of light continue
“The purpose of the Workshop was to address the question of how melanopsin photo- receptors impact methods of measuring light by [composing] a review article summarizing current areas of consensus and uncertainty and, to the extent possible, provide advice for measuring light”

31. Designing for circadian effect
Industry efforts to qualify and quantify the biological effects of light continue
“The shortcomings of the existing evidence highlight the need for further research...[so] the Workshop should reconvene in five years .”

32. Designing for circadian effect
Eα = ∫ Ee,λ(λ) Nα(λ) dλ
Wavelength
Luminous Efficiency
380
420
460
500
540
580
620
660
700
Relative Sensitivity (normalized)
0.4
0.6
0.8
1.0
ipRGC V
0.2
0.0
Equivalent Melanopic Lux (E ) is derived using factors for each wavelength of light exposure based on average photopic response and the ipRGC /melanopsin sensitivity curve

33. Designing for circadian effect
Eα = ∫ Ee,λ(λ) Nα(λ) dλ
Wavelength
Luminous Efficiency
380
420
460
500
540
580
620
660
700
Relative Sensitivity (normalized)
0.4
0.6
0.8
1.0
ipRGC V
0.2
0.0
Equivalent Melanopic Lux (E ) is derived using factors for each wavelength of light exposure based on average photopic response and the ipRGC /melanopsin sensitivity curve
EML is the basis for Feature 54 of The Well Building Standard
EML is based on melanopsin response, not melatonin suppression

34. Designing for circadian effect
RPI’s Lighting Research Center has created a model for Circadian Light (CLA ) and Circadian Stimulus (CS)
CLA correlates acute melatonin response with the corneal irradiance response of the ipRGCs (versus the average photopic response)
CS then is defined as the level of acute melatonin suppression after 1 hour of exposure

35. Designing for circadian effect
RPI’s Lighting Research Center has created a model for Circadian Light (CLA ) and Circadian Stimulus (CS)
A corresponding Circadian Stimulus Calculator for comparing light sources can be found at: tHealth/

36. Designing for circadian effect
RPI’s Lighting Research Center has created a model for Circadian Light (CLA ) and Circadian Stimulus (CS)
A corresponding Circadian Stimulus Calculator for comparing light sources can be found at: tHealth/

37. Circadian Stimulus (CS)
Designing for circadian effect
LRC model for Circadian Light
The LRC CS model appears to be a good fit to known data points
Circadian Light (CLA) 1 10
100
1000
10,000 20 60 70
- 1
100,000 50 40 30
Melatonin Suppression (after 1 hour exposure)
0.1
-0.2
0.6
0.7
0.5
0.4
0.3
- 0.1
Circadian Stimulus (CS)

38. Circadian Stimulus (CS)
Designing for circadian effect
LRC model for Circadian Light
The LRC CS model appears to be a good fit to known data points
Research shows that exposure to a CS of 0.3 or greater at the eye, for at least 1 hour in the early part of the day, is associated with better sleep and improved mood.
/lightHealth/
Circadian Light (CLA) 1 10
100
1000
10,000 20 60 70
- 1
100,000 50 40 30
Melatonin Suppression (after 1 hour exposure)
0.1
-0.2
0.6
0.7
0.5
0.4
0.3
- 0.1
Circadian Stimulus (CS)

39. Existing evidence Veitch et al. (2012)
82 Subjects with controllable ambient lighting color
Higher color temperature improved performance
Choice improved satisfaction, but had little effect on performance

40. Existing evidence Smolders & de Kort, 2017)
39 subjects in 2x2 design (CCT and time)
Greater feeling of vitality with cool temperature
Satisfaction and mood decreased in cool temperature
Effect for performance and time of day not found

41. Existing evidence Canazei et al. (2017)
31 subject complete three overnight trials
500 lux horizontal, 150 lux vertical
Heart rate was lower with warmer light
Mood and performance were not effected
39 subjects in 2x2 design (CCT and time)

42. Field study Research questions - two factors:
What are the effects of different ambient color spectrums
What are the effects of occupant control of task lighting

43. Field study Research questions - two factors:
Four workstations with combination task / ambient luminaires
No natural light
Partitions to limit interaction of task lights
Positive soundscape
Regular working conditions

44. Field study Research questions - two factors:
Four workstations with combination task / ambient luminaires
No natural light
Partitions to limit interaction of task lights
Positive soundscape
Regular working conditions

45. Field study Warm Ambient Cool Ambient Achieved light spectrum
Ambient spectrum: Warm = 2613K Neutral = 3259K Cool = 5114K
Illuminance: 229 lux
Melanopic illuminance: Warm = 100 EML Neutral = 137 EML Cool = 209 EML
Photopic
Melanopic
Warm Ambient
Cool Ambient

46. Executive Functioning Spatial Working Memory
Field study
Tower of London
Executive Functioning
Corsi Block Test
Spatial Working Memory
PEBL – The Psychology Experiment Building Language
Five experiments, each about 2-3 minutes
Corsi Block Test
Tower of London
Oddball Task
Free Recall Task
Switcher Task
Satisfaction survey

47. Field study Free Recall Task Working Memory Oddball Task
Prefrontal Strategy
PEBL – The Psychology Experiment Building Language
Five experiments, each about 2-3 minutes
Corsi Block Test
Tower of London
Oddball Task
Free Recall Task
Switcher Task
Satisfaction survey

48. Cognitive Flexibility
Field study
Switcher Task
Cognitive Flexibility
Satisfaction Survey
PEBL – The Psychology Experiment Building Language
Five experiments, each about 2-3 minutes
Corsi Block Test
Tower of London
Oddball Task
Free Recall Task
Switcher Task
Satisfaction survey

49. Field study Z-scores for Participant ‘1’ Pilot findings
Higher cognitive performance with cool temperature
Lower satisfaction with cool temperature
Interaction of ambient & task light, TBD

50. Implications Daylight is the elephant in the room.
Vertical surfaces and occupant orientation are critical design considerations

51. Circadian Stimulus (CS)
Implications
Research shows that exposure to a CS of 0.3 or greater at the eye, for at least 1 hour in the early part of the day, is associated with better sleep and improved mood.
tHealth/
Planned lighting at the individual level and controllability
Circadian Light (CLA) 1 10
100
1000
10,000 20 60 70
- 1
100,000 50 40 30
Melatonin Suppression (after 1 hour exposure)
0.1
-0.2
0.6
0.7
0.5
0.4
0.3
- 0.1
Circadian Stimulus (CS)
Daylight
Incandescent
1000 lux
300 lux
100 lux
30 lux
outdoors
night
indoors
office
home
Outdoors daytime

52. Implications
Traditional tension between having enough light and energy code

53. Implications
Traditional tension between having enough light and energy code
Non-visual effects of light add a layer of complexity to lighting decisions

54. Implications
Traditional tension between having enough light and energy code
Non-visual effects of light add a layer of complexity to lighting decisions
Each factor has different impacts on the health of occupants

55. Implications
Traditional tension between having enough light and energy code
Non-visual effects of light add a layer of complexity to lighting decisions
Each factor has different impacts on the health of occupants
Occupants, owners, and designers each play a role in determining outcomes

56. David Pfund President, tambient Stuart Shell, AIA Project Manager
This completes the CEU portion of this presentation.
Questions?
David Pfund
President, tambient
Stuart Shell, AIA
Project Manager

57. References
Ashley, N. T., Walton, J. C., Haim, A., Zhang, N., Prince, L. A., Fruchey, A. M., ... & Nelson, R. J. (2013). Sleep deprivation attenuates endotoxin-induced cytokine gene expression independent of day length and circulating cortisol in male Siberian hamsters (Phodopus sungorus). Journal of Experimental Biology, 216(14),
Canazei, M., Pohl, W., Bliem, H. R., & Weiss, E. M. (2017). Acute effects of different light spectra on simulated night-shift work without circadian alignment. Chronobiology international, 34(3),
Denk, E., Jimenez, P., & Schulz, B. (2015). The impact of light source technology and colour temperature on the well- being, mental state and concentration of shop assistants. Lighting Research & Technology, 47(4),
Smolders, K. C., & de Kort, Y. A. (2017). Investigating daytime effects of correlated colour temperature on experiences, performance, and arousal. Journal of Environmental Psychology, 50,
Veitch, J. A., Dikel, E. E., Burns, G. J., & Mancini, S. (2012). Office light source spectrum: effects of individual control on perception, cognition, and comfort. National Research Council Canada.