FACULTY OF ARCHITECTURE,DESIGN & PLANNING

Shifting Our Vision for Lighting

Lux America 2012

Wendy Davis

Associate Professor

Director Illumination Design

2

Why do we light?

We do not light to:

• Expend / save energy• To meet standards & building codes• To meet budgets• To use particular technologies

Image from: http://www.csiro.au/en/Outcomes/Energy/Saving-energy-

in-your-home.aspxImage from:

http://nyack-ny.gov/departments/building/

Image from: http://rabbishishler.blogspot.com.au/2012/02/soul-

budget.html

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Why do we light?

We light so that people can see:

• Books• Faces• Artwork• Stairways• Etc.

Image from: http://www.optforhealthyliving.org/

Image from: http://www.guardian.co.uk/world/2010/nov/25/ernest-cole-

david-goldblatt-apartheid-photography

Image from: http://www.autism-community.com/a-plethora-of-literacy-resources/

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Fixation with the incandescent lamp

The ways we measure, evaluate and communicate about lighting are technology-focused & backward-looking

Image from: http://cheaptalk.org/2011/03/18/backward-and-forward-looking-organizations/

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Correlated colour temperature (CCT)

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Correlated colour temperature (CCT)

+ Duv

- Duv

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Colour rendering index (CRI)

Reference illuminantTest source

Planckian(CCT<5000 K)

CIEDxx

Standard Daylight(CCT > 5000 K)

Same CCT [K]

#1 #2 #3 #4 #5 #6 #7 #8

#9 #10 #11 #12 #13 #14

Ra

4 0 0 4 5 0 5 0 0 5 5 0 6 0 0 6 5 0 7 0 0

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Colour rendering index (CRI)

= perfect?

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Colour rendering index (CRI)

Neodymium incandescent lamp

CRI = 77

(normal incandescent lamp CRI=100)

Ref.

LED

Image from: http://www.ge.com/innovation/timeline/eras/breakthrou

gh_discoveries.html

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Colour rendering index (CRI)

3-LED ModelPeaks at: 464, 538, 620 nm

CRI = 63

Ref

LED

Image from: http://glassbox-design.com/2009/elos-rgb-led-prototype-changes-colors-on-demand/

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Further complications

Hunt Effect

Colorfulness / saturation increases with luminance

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Moving beyond the incandescent

Image from: http://www.eralight.biz/led-bulb/e27-led-bulb.html

Image from: http://www.alibaba.com/product-gs/303496832/F96T12_r

eplacement_LED_tube.html

Retrofits / replacement lamps:

• Minimal consumer investment• Compatible with existing infrastructure• Reversible

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Moving beyond the incandescent

Image fromhttp://news.cnet.com/8301-11386_3-57428951-76/philips-led-replaces-100-watt-incandescent/

Image from: http://elektro-vault.blogspot.com.au/2012/06/27w-led-to-replace-100w-bulb.html

Retrofits / replacement lamps:

• Difficult to engineer• Fail to capitalize on benefits of newer technologies• Presume incumbent technologies are optimal

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Moving beyond the incandescent

Disruptive technology

“A new technology that changes the current way of approaching a particular problem or issue”1

1http://elearningfacultymodules.org/index.php/E-Learning_Terminology

Images from: Wikipedia Commons

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Moving beyond the incandescent

Image from: http://www.canstockphoto.com/illustration/imagine.html

Let’s imagine…

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How far could we go?

Image from: http://johngushue.typepad.com/blog/2010/06/technolo

gy.html

Image from: Wikipedia Commons

Image from: http://www.cnet.com.au/apple-iphone-4-339303698.htm

Image from: http://dekhomobile.blogspot.com.au/2011/11/latest-

glass-mobile-phone-latest-mobile.html

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How do we get there?

Image from: http://www.guardian.co.uk/voluntary-sector-network/2012/jun/13/charity-conduct-strategic-review-advantages

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Colour vision

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Principle of Univariance

• The cones transmit no spectral information

• Countless different spectra can lead to identical patterns of cone activity

• Perceptions of colour arise from combining and comparing the activity of the different cone classes

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Trichromacy

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Colour matching functions

390 440 490 540 590 640 690 740-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

r

g

b

wavelength (nm)

tris

tim

ulu

s v

alu

e

r(λ)g(λ)b(λ)390 440 490 540 590 640 690 740

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

xyz

wavelength (nm)

tris

tim

ulu

s v

alu

e

x(λ)y(λ)z(λ)

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Colour matching functions

• x + y + z = 1• (x, y) is a 2-dimensional representation of chromaticity.• Y is a measure of visual intensity of light stimulus.• x, y, Y fully describe light stimulus.

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Colour opponency

Image from: http://facweb.cs.depaul.edu/sgrais/color_perception.htm

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Colour opponency

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Colour opponency

390 440 490 540 590 640 690 740

-100

-80

-60

-40

-20

0

20

40

60

red-green

blue-yellow

wavelength (nm)

ou

tpu

t

yellow

green

redred

blue

DeValois & DeValois (1993)

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Moving beyond the incandescent

Metamers

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Luminous efficacy

Luminous efficacy = radiant efficiency x luminous efficacy of radiation (LER)

LER = 408 lm/WLER = 154 lm/W

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Colour rendering

Four lasers

Image from: Wikipedia Commons

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Object reflectance

400 450 500 550 600 650 7000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

RedYellowGreenBlue

wavelength (nm)

refle

cta

nce

(p

rop

ort

ion

)

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Object reflectance

00.10.20.30.40.50.60.70.80.9

1

380 480 580 680

wavelength (nm)

refle

cta

nce

artificial

real

Image from: http://greatfruitpictures.onsugar.com/Orange-Fruit-Picture-18993899

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Visual processing

390 440 490 540 590 640 690 740

-100

-80

-60

-40

-20

0

20

40

60

red-green

blue-yellow

wavelength (nm)

ou

tpu

t

yellow

green

redred

blue

DeValois & DeValois (1993)

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Moving forward

• Spectral design & colour properties

• Size & shape of lighting products

• Spatial distribution of light

• Modes of control & human interaction

• …

Image from: http://gooddisruptivechange.com/why-change-your-mindset/