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    Key Objectives in Lighting Design: Visual Performance Physiological Conditions Visual Quality

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    Erwin Syah
    The document discusses key concepts in lighting design including visual performance, physiological conditions, and visual quality. It then covers radiometric and photometric quantities such as flux, illuminance, intensity, and luminance. These quantities are measured using different units depending on whether an absolute or visible light-dependent approach is used. Various examples of these quantities in common light sources are also provided.

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    Key Objectives in Lighting Design: Visual Performance Physiological Conditions Visual Quality

    Uploaded by

    Erwin Syah
    30 views24 pages
    The document discusses key concepts in lighting design including visual performance, physiological conditions, and visual quality. It then covers radiometric and photometric quantities such as flux, illuminance, intensity, and luminance. These quantities are measured using different units depending on whether an absolute or visible light-dependent approach is used. Various examples of these quantities in common light sources are also provided.

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    MIT OCW

    Original Title

    lec11

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    The document discusses key concepts in lighting design including visual performance, physiological conditions, and visual quality. It then covers radiometric and photometric quantities such as flux, illuminance, intensity, and luminance. These quantities are measured using different units depending on whether an absolute or visible light-dependent approach is used. Various examples of these quantities in common light sources are also provided.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    30 views24 pages

    Key Objectives in Lighting Design: Visual Performance Physiological Conditions Visual Quality

    Uploaded by

    Erwin Syah
    The document discusses key concepts in lighting design including visual performance, physiological conditions, and visual quality. It then covers radiometric and photometric quantities such as flux, illuminance, intensity, and luminance. These quantities are measured using different units depending on whether an absolute or visible light-dependent approach is used. Various examples of these quantities in common light sources are also provided.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 24

    Key objectives in Lighting design

    Visual performance
    Physiological conditions
    Visual quality

    no strong "contrasts"
    good "color rendering"
    adequate "light levels"
    no "disturbing reflections"
    no direct "glare"

    Radio- and photometric quantities


    Radiometry vs. Photometry
    1.0
    0.9
    0.8

    Relative Efficiency [-]

    absolute (energy)
    vs.
    V()-dependent (light)

    0.7
    0.6
    0.5
    0.4
    0.3
    0.2
    0.1
    350

    400

    450

    500

    550

    600

    650

    700

    750 800

    Wavelength [nm]

    Image by MIT OCW.

    Radio- and photometric quantities


    Radiometry vs. Photometry
    absolute (energy)
    vs.
    V()-dependent (light)

    1.0

    Relative efficiency [-]

    1.9
    1.8
    1.7
    1.6
    1.5
    1.4
    1.3
    1.2
    1.1
    350

    400

    450

    500

    550

    600

    650

    700

    750

    800

    Wavelength (nm)

    Image by MIT OCW.

    Radio- and photometric quantities


    Four major quantities

    flux
    illuminance
    intensity
    luminance

    Image by MIT OCW.

    Radio- and photometric quantities


    Flux
    energy / unit of time

    in Watts [W] vs. lumen [lm]

    Image by MIT OCW.

    Radio- and photometric quantities


    Flux
    energy / unit of time

    in Watts [W] vs. lumen [lm]

    683 lumen/Watt at 555 nm : lum [lm] = 683 V() e [W]


    Incandescence

    Discharge
    70 watts

    75 watts

    very
    different
    efficacies !

    1055 lumens

    Images by MIT OCW.

    5600 lumens

    Radio- and photometric quantities


    Flux
    Illuminance
    flux received / unit of surface
    E in [W/m2] vs. [lm/m2] or lux [lx]

    Images by MIT OCW.

    Radio- and photometric quantities


    Flux
    Illuminance
    flux received / unit of surface
    E in [W/m2] vs. [lm/m2] or lux [lx]
    Full moon

    0.01 Lux

    Overcast sky

    Sunlight

    8'000 - 20'000 Lux

    100'000 Lux
    Image by MIT OCW.

    Radio- and photometric quantities


    Flux
    Illuminance
    flux received / unit of apparent surface (cosine ("Lambert") law)
    E in [W/m2] vs. [lm/m2] or lux [lx]

    E =

    E = E. cos

    Images by MIT OCW.

    Radio- and photometric quantities


    Flux
    Illuminance
    flux received / unit of apparent surface (cosine ("Lambert") law)
    E in [W/m2] vs. [lm/m2] or lux [lx]
    measurement with lux-meter (illumance-meter)
    Requirements Lux

    Examples

    Low

    20-70

    Circulation, stairs

    Moderate

    120-185 Entrance, restaurant

    Medium

    250-375 General tasks

    High

    500-750 Reading, Writing

    Very high

    > 1000

    Precision tasks

    Radio- and photometric quantities


    Flux
    Illuminance

    flux received / unit of apparent surface (cosine ("Lambert") law)


    E in [W/m2] vs. [lm/m2] or lux [lx]
    measurement with lux-meter (illumance-meter)
    exitance M for emitted flux [lux]

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity
    flux emitted "in a certain direction"

    Images by MIT OCW.

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity
    flux emitted within a certain solid angle
    A = .d2
    A
    = 2
    d

    Images by MIT OCW.

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity
    flux emitted within a certain solid angle
    I in [W/sr] vs. [lm/sr] or Candela [Cd]

    1 Candela = intensity of one candle

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity
    flux emitted within a certain solid angle
    I in [W/sr] vs. [lm/sr] or Candela [Cd]
    inverse square law for point source

    E = I cos() / d2

    Image by MIT OCW.

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity

    flux emitted within a certain solid angle


    I in [W/sr] vs. [lm/sr] or Candela [Cd]
    inverse square law for point source
    intensity distribution

    240o

    120o

    270o

    90o
    100

    300o

    200

    60

    300
    400
    o

    330

    30o

    Image by MIT OCW.

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity

    180o

    105

    120

    13

    165 o

    flux emitted within a certain solid angle


    I in [W/sr] vs. [lm/sr] or Candela [Cd]
    inverse square law for point source
    intensity distribution

    150 o
    90

    30
    40

    75 o

    60

    80
    100

    60 o

    120
    140

    180 cd

    160

    h = 10 ft

    45

    180

    200
    o

    15

    30

    Image by MIT OCW.

    Radio- and photometric quantities


    Flux

    Ns

    Source

    Illuminance
    Intensity
    Luminance

    I
    Ss

    flux emitted by apparent


    surface in a given direction
    I/m2 (or M/sr)
    L in [Cd/m2]

    Images by MIT OCW.

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity
    Luminance
    flux emitted by apparent
    surface in a given direction
    I/m2 (or M/sr)
    L in [Cd/m2]
    L = I / Sa
    L = I / (S . cos )

    Sa

    Radio- and photometric quantities


    Flux
    Illuminance

    Specular

    Spread

    Diffuse

    Specular/Spread

    Diffuse/Spread

    Intensity
    Luminance
    flux emitted by apparent
    Diffuse/Specular
    surface in a given direction
    I/m2 (or M/sr)
    Intensity variation
    L in [Cd/m2]

    lambertian surface

    Image by MIT OCW.

    Luminance variation

    lambertian surface

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity
    Luminance

    Cd/m2
    Primary sources
    Sun
    1 650 000 000
    Incandescent lamp (100 W, bright)
    6 000 000
    Incandescent lamp (100 W, frosted)
    125 000
    Fluorescent tube (40 W, 38 mm)
    5000 - 8000
    Candle
    5000
    Computer screen
    100-200

    flux emitted by apparent


    surface in a given direction
    I/m2 (or M/sr)
    L in [Cd/m2]

    Radio- and photometric quantities


    Flux
    Illuminance
    Intensity

    Secondary sources
    Moon
    White paper ( = 0.8, E = 400 lux)
    Grey paper ( = 0.4, E = 400 lux)
    Black paper ( = 0.01, E = 400 lux)
    Minimal luminance perceived:

    Luminance
    flux emitted by apparent
    surface in a given direction
    I/m2 (or M/sr)
    L in [Cd/m2]

    Cd/m2
    2 500 - 3000
    100
    50
    5
    10-5

    Radio- and photometric quantities


    Luminance measurement
    Eye = luminance-meter

    Photometry
    Reading assignment from Textbook:
    Introduction to Architectural Science by Szokolay: 2.1

    Additional readings relevant to lecture topics:


    "IESNA Lighting Handbook" (9th Ed.): pp. 2-1 to 2-3 + pp. 3-1 to
    3-5 + pp. 3-9 to 3-14 + pp. 4-1 to 4-6

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