introduction to the radiancy and the colour 2008 technical advisory service

Introduction to the radiancy and the colour

2008

Technical Advisory Service


The radiancy The solar spectrum The light Light transmission and reflexion Energetic transmission and reflexion Protection of the glass against radiancy The colour Conclusion

The radiancy

Solar radiancy Radiators

Close IR

Long IR

Radio waves

Visible

The radiancy

Type of radiancy Wavelength

Gamma rays from 0 to 0,01 nm

X rays from 0,01 nm to 10 nm

Ultraviolet (UV) - UV C - UV B - UV A

from 10 nm to 380 nm from 2 nm to 280 m from 280 nm to 315 nm from 315 nm to 380 nm

Light from 380 nm to 780 nm

Infrared (IR) - close IR A IR B - long IR C

from 780 nm to 106 nm from 780 nm to 1400 nm from 1400 nm to 2500 nm from 2500 nm to 106 nm

Radio waves from106 nm to several km

Solar

spectrum

The radiancy

Type of radiancy Application - Effect

Gamma rays

X rays Radiography

Ultraviolet (UV)

EnergyTanningCancer of the skinBlanching of objects

Light Light

Infrared (IR) - close IR A IR B - long IR C

Energy of the solar radiancy

Energy emitted by objects (radiators)

Radio waves Radios

The solar spectrum

0

0.5

1.0

1.5

Intensity(W/m²)

Wavelength(nm)

0

280 380 780

Energy

2500

UV Light Short infra red

The solar spectrum

UV : 280 to 380 nm 5% energy

Light : 380 to 780 nm 50% energy

Short I.R. : 78O to 2500 nm 45% energy

The solar spectrum

Solar constant : 1353 W/m²

reflective

absorbed

dispersed

direct

0

0.5

1.0

1.5

Intensity(W/m²)

Wavelength(nm)

0

280 380 780 2500

Light

The solar spectrum

The ligth

The ligth

(nm) 380 400 500 600 700 800

Violet 380 to 462 nm

Blue 462 to 500 nm

Green 500 to 577 nm

Yellow 577 to 600 nm

Orange 600 to 625 nm

Red 625 to 780 nm

Light transmission and reflexion (380–780 nm)

v = LT = transmitted light incident light

Light

LT

v

LR

v

the light transmission depends on :

the transmission’s curve of the product

the reference illuminant

the eye sensibilty


Transmission curve of the productSingle glazing 6 mm

Longueur d’onde (nm)

90

80

60

50

40

30

20

10

70CLAIR

BRONZEGRIS

AZURVERT

280380 780 1000 2000

0

2480

Tra

nsm

issi

on (

%)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

280 780 1280 1780 2280

PRIVA BLUE


Reference illuminant


Reference lighting up :

A: filament light bulb (automotive)

C65: natural light

D65: natural light (EN 410)


Eye sensitivity


00.10.20.30.40.50.60.70.80.9

1

400 500 600 700

Longeur d'onde (nm)

Ré

po

ns

e

Light transmission

780

380

780

380

)(E.)(S

)(E.)(S.)(LT

With = transmission curve of the product

S() = eye sensitivity

E() = reference illuminant


Light reflexion

780

380

780

380

)(E.)(S

)(E.)(S.)(LR


S() = eye sensitivity

E() = reference lighting up


Index of reproduction of colours RD65

This index gives a quantitative evaluation of the difference in color between 8 samples of color-test lit directly by illuminating D65,and the light coming from same illuminating, transmitted by the glazing


}SF

SF = g = transmitted heat incident heat

e

qiqe

ER

e

Heat

Energetic transmission and reflexion (300–2500 nm)

Energetic equation : DET + EA + ER = 100 %

e = ER = energetic reflexion

e = DET = direct energetic transmission

e = EA = energetic absorption

SF = g = solar factor = total energetic transmission


Clear glazing

100

0

50

280 380 780 1000 2000 2500

Stopray Safir

Tra

nsm

issi

on (

%)

Wavelength (nm)


Direct energetic transmission

2500

300

2500

300

)(

)(.)(

E

EDET


E() = solar spectrum of reference


Solar factor (monolithic glazing)

EAhh

hDETSF

ei

i .


837,0

.4,46,3 cor

ih

78,0.1,7 vhe

For clear glazing, we have hi = 8 W/(m²K)

and he = 23 W/(m²K)


he = coefficient of surface heat exchange between the wall and the external environment absorption

hi = coefficient of surface heat exchange between the wall and the interior environment

Transmission et réflexion énergétique (300–2500 nm)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

250 500 750 1000 1250 1500 1750 2000 2250 2500

Longueur d'onde (nm)

Inte

nsi

té (W

/m².n

m)

EN 410 1997

ISO 9050 2003

ISO 9050 1990 t2


Remarks : indexes of the USA standards

SHGC (solar heat gain coefficient) = SFS

SC (shading coefficient) = sS/87 SC sw = DET/87 SC lw = SC – SC sw

Relative Heat Gain: RHG (W/m²) = 630 SC + 7,8 U

Protection of the glass against radiancy

Protection against X rays

Glass with high lead content


Protection against the UV

Laminated glass

TrUV, SPF, Krochman KDF The less the UV transmission, the less UV

penetrate int he building

Caution: no UV transmission is not synonymous with absence of discolouration (blanching)


Protection against the light and lighting of the buildings

Coloured glazings, coated glass

TL

The highest the LT, the more light comes into the building. The lighting level of the buildings depends on the LT

See training «Glass and solar control»


Protection against vision

Opaque, mat, painted, printed glazings …


Protection against short IR and the heat

Ccoloured glass, coated glass

SF, (TrIR)

The lowest the SF, the lowest heat comes into the building. The system of air conditioning of a building depends on the level of SF

See training «Glass and solar control»


Protection against long IR

Low emissivity glass (Top N, Top NT, Stopray, Planibel G, Sunergy)

Emissivity Ug

The heating system depends on the level of insulation of the building

See training «Glass and thermal insulation»


Protection against radio waves

Electrified coated glass

The colour

The colour

The colour of an object depends on : the illuminant which lights the object the object itself which modifies by

transmission or reflexion the received light the eye of the observer and the transfer of

the image towards the brain

The colour

The colour

To quantify a colour, it is thus necessary to know :

the spectrum of energy emitted by the source of light

the spectrum of transmission or reflexion of the object

the response of the human eye

The colour

Guild & Wright experiment

The colour

The colour

R, B, V graphic

The colour

CIE 1931 colorimetric graphic

0

0.5

1

1.5

2

380 480 580 680 780

x

y

z

The colour

780

380

_

780

380

_

)(.)(

)(.)(.)(

Ey

ExX

780

380

_

780

380

_

)(.)(

)(.)(.)(

Ey

EyY

780

380

_

780

380

_

)(.)(

)(.)(.)(

Ey

EzZ

Tristimuli X, Y, Z:

The colour

The colour

Tristimuli X, Y, Z:

Rem: Y = TL

Inconvenience : Are not sufficient to

differentiate all the colours.

The colour

ZYX

Xx

Trichromaticity coordinates x, y, z:

ZYX

Yy

ZYX

Zz

1 zyxwith

The colour

Trichromaticity coordinates x, y, z:

Only 2 independent coordinates

So we use : x, y, Y = TL

The colour

Diagram of trichromaticity CIE 1931:

contains 2 axis x and y

sources A, B, C, D, … according to the used

illuminant

graduated wavelengths on the border =

dominant wavelength

the pureness of the tint P = m/n

(0,2; 0,5)

n m

The colour


Example: A point of coordinates (x, y) = (0,2;

0,5) corresponds to :

a green colour

a dominant wavelength = 512 nm

a pureness of tint P = 4/10 = 0,4

The colour


Inconveniences :

The inferior side of the graphe corresponds to

multichromatics colours

we specify a negative dominant

wavelength

This system is not proportional to what the

eye can see.

The colour

The colour

Hunter Lab System :

nY

YL .100

nY

YYn

Y

Xn

XKa

a)(.

nY

YZn

Z

Yn

YKb

b)(.

The colour

CIE L*a*b* System:

16.116* 3 nY

YL

33.500*Yn

Y

Xn

Xa

33.200*

Zn

Z

Yn

Yb

The colour

Système CIE L*a*b*:

The colour

The colour

Difference of coulour between 2 products :

)²()²()²( baLEab

*)²(*)²(*)²(** baLE ba

The colour

The colour

0

0.5

1

1.5

2

2.5

380 480 580 680 780

x (1964)

y (1964)

z (1964)

x (1931)

y (1931)

z (1931)

CIE 1931 and CIE 1964 colorimetric graphic

The colour

The colour

Summary : Different systems exist :

X, Y, Z

x, y, z

Lab

L*a*b*

CIELCH (L*, C*, h); UCS (Y, u’, v’), …

The colour

Summary : In order to characterize a colour at

the best, we must specify 5 values :

3 coordinates of colour

1 illuminant

1 angle of observation

Example: Lab, D65, 2°

Conclusion

Conclusions

Stopray Neutral 50/40 (LR = 15)

Conclusion

The perception (colour, level of transmission and reflexion, …) that we have from an object, depends on : the object the illuminant the level on luminosity its environment (contrast)

A same objet (thus a same glazing) will have a different aspect depending on its location, the time of the day, the surrounding objects, …

introduction to the radiancy and the colour 2008 technical advisory service

Documents

nm slide

light light transmission

light reflexion

nm red625

nm blue462

nm green500

nm yellow577

nm orange600