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Lighting Guide

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1 Lighting Guide .......................................................................................................................... 3 2 Illuminance level ...................................................................................................................... 3 3 Glare prevention ....................................................................................................................... 4

3.1 Shielding .............................................................................................................................. 4 3.2 Placing fixtures .................................................................................................................... 4 3.3 Rooms with computer displays ............................................................................................ 5

4 Types of Lumiance fixtures ..................................................................................................... 5 4.1 General lighting ................................................................................................................... 5 4.2 Accent lighting ..................................................................................................................... 5 4.3 Wall washing ....................................................................................................................... 5 4.4 Local lighting ........................................................................................................................ 6 4.5 Decorative lighting ............................................................................................................... 6 4.6 Emergency lighting .............................................................................................................. 6

5 Fixture data ............................................................................................................................... 6 5.1 Polar diagram ...................................................................................................................... 6 5.2 Cartesian diagram ............................................................................................................... 7 5.3 Performance cone ............................................................................................................... 7 5.4 Isolux curve ......................................................................................................................... 7 5.5 Fast calculation table ........................................................................................................... 8 5.6 Utilization Factor (UF) .......................................................................................................... 8 5.7 Energy consumption per 100 lx per m2 ................................................................................ 9 5.8 Illuminance in standard grid ................................................................................................. 9 5.9 EULUMDAT ......................................................................................................................... 9 5.10 Unified Glare Rating (UGR) ............................................................................................ 10 5.11 Söllner Diagram .............................................................................................................. 11

6 Lighting of light-sensitive objects ........................................................................................ 11 6.1 Prevention of damage ....................................................................................................... 11 6.2 Light fastness .................................................................................................................... 11 6.3 Advised maximum illuminance .......................................................................................... 12 6.4 Filters ................................................................................................................................. 12 6.5 Calculation of the allowed illumination time ....................................................................... 12 6.6 Damage prevention with Lumiance products .................................................................... 12

7 Lighting terminology ............................................................................................................. 13 7.1 Light ................................................................................................................................... 13 7.2 Luminous flux .................................................................................................................... 13 7.3 Illuminance ........................................................................................................................ 14 7.4 Luminance ......................................................................................................................... 15 7.5 Colour temperature ............................................................................................................ 15 7.6 Colour rendering index ...................................................................................................... 16 7.7 Uniformity ratio .................................................................................................................. 16 7.8 SHR ................................................................................................................................... 16 7.9 Room index k ..................................................................................................................... 16 7.10 Maintenance factor ......................................................................................................... 16 7.11 Specific luminous flux ..................................................................................................... 17 7.12 Light Output Ratio (LOR) ................................................................................................ 17 7.13 Utilization Factor (UF) .................................................................................................... 17

Lighting Guide


1 Lighting Guide

This guide provides background information for the application of Lumiance fixture data. Lighting levels, glare values and other photometric characteristics of lighting projects can be assessed with graphs and diagrams from data sheets or with computer calculations. Technical data of Lumiance fixtures is available on paper in the form of tables and graphs and also as files for use in computer programs. A computer program is also available. Legal requirements are indicated for guidance only. In some countries and in specific projects, different regulations may apply. If in doubt, consult an expert.

2 Illuminance level

To determine how much light is required, account must be taken of the type of visual task:

To be able to safely find the emergency exit in a building, 1 lx is sufficient

To be able to distinguish facial expressions, approx. 20 lx is required

For accent lighting in shop windows, 1500 – 2000 lx is usual

Operation tables must be illuminated with a minimum of 5000 lx In rooms where people work, legal minima apply for the illuminance, depending on the room and on the visual task. Examples from European standard EN12464, Lighting of Indoor Work Places: 50 lx stable 75 lx parking area 100 lx storage space 200 lx canteen 300 lx classroom 500 lx professional kitchen 750 lx fine assembly work 2000 lx engraving installation 5000 lx operation table These minima relate to the average illuminance in the working area. The uniformity in the working area may not be less than 0.7, and not less than 0.5 In the immediate surroundings. The initial illuminance values must be higher than the legal minima, because account must be taken of light degradation caused by contamination and ageing of lamps and fixtures.

Lighting Guide


3 Glare prevention

Glare occurs when one part of the visual field is much brighter than the average brightness to which the visual system is adapted. Glare is divided into discomfort glare and disability glare. Measures have to be taken to limit discomfort glare in lighting installations.

3.1 Shielding

A shielding angle can be stated for open fixtures and for fixtures that are supplied with a clear, non-structured covering. The shielding angle is the angle from which the lamp or its reflection in the reflector is no longer visible. The following minima apply according to the European standard EN 12461, Lighting of Indoor Work Places. Luminance (kcd/m2) Example Minimum shielding angle (º) 1 to 20 fluorescent tube 10 20 to 50 compact fluorescent lamp 15 50 to 500 discharge lamp (mat) 20 more than 500 discharge lamp (clear) 30

3.2 Placing fixtures

Reflections from fixtures on glossy paper can make it difficult to read printed matter. This type of glare is called veiling glare. Fixtures must be placed in the room such that veiling glare is avoided

Discomfort glare causes symptoms of visual fatigue

Disability glare impairs vision

30°

30° 30°

Lighting Guide


3.3 Rooms with computer displays

The European standard EN 12464, Lighting of Indoor Work Places, contains regulations with regard to the allowed luminance of fixtures of which the mirror image can be visible in computer displays. If light is emitted at an angle of 65º or more to the vertical axis of a fixture, the luminance above this angle may not be more than 1000 cd/m2. When using displays with light characters on a dark background, a maximum of 200 cd/m2 applies. According to the British standard CIBSE LG3, fixtures can be subdivided into three categories:

Category 1 - 55º Suited for rooms where people work intensively with computer displays

Category 2 - 65º Suited for rooms where people work regularly with computer displays

Category 3 - 75º Suited for rooms where people now and then perform simple work with computer displays

For all three categories, the luminance may not exceed 200 cd/m2 above the stated angles.

4 Types of Lumiance fixtures

4.1 General lighting

General artificial lighting is provided by ceiling fixtures that are installed in a regular pattern. General lighting is mostly soft in nature with few shadows and differences in brightness.

4.2 Accent lighting

Accent lighting is used to emphasise the characteristic aspects of an interior or as an eye catcher in shop windows, shops, galleries or in the living room. Accent lighting is achieved by locally increasing the illuminance and by consciously introducing shadows to enhance the three-dimensional effect. For the local increase of the illuminance, beamed light is required.

4.3 Wall washing

With wall washing, the walls are illuminated as evenly as possible. This can be done for functional reasons, for esthetical purposes or to improve visual comfort. In rooms with general lighting the contrast ratios in the field of vision improve if the walls are also illuminated. This can be done with wall washers or with accent lighting fixtures.

Lighting Guide


4.4 Local lighting

Extra fixtures are often placed in task areas. The necessary illuminance depends on the character of the task that is being performed.

4.5 Decorative lighting

Certain types of lighting fixtures are used for beautification rather than for lighting purposes.

4.6 Emergency lighting

Emergency lighting should start automatically as soon as the mains voltage drops below 70% of its rated value. See the Lumiance Emergency Lighting Guide for further details.

5 Fixture data

Technical data of Lumiance fixtures is available on paper in the form of tables and graphs and also as files for use in computer programs. A computer program is also available. For reflector lamps, the data from the lamp manufacturer must be used.

5.1 Polar diagram

The polar diagram is the graphic representation of the luminous intensity in different directions. The value of the luminous intensity is indicated in candelas per 1000 lumen (cd/klm). This value must be multiplied by the luminous flux of the used lamp(s). Example: 1000 cd/klm corresponds with 400 cd with a 400 lm lamp and with 1100 cd with an 1100 lm lamp. If two curves are plotted in one diagram, the intensity distributions are different in two vertical planes or in all four half planes: C0, C90, C180 and C270. C0 is one of the two half planes perpendicular to the axis of the lamp. The half plane in which the highest luminous intensity has been measured is taken as C0 in Lumiance data files.

Gamma ( ) is the angle between the optical axis of the luminaire and the direction in which a particular luminous intensity value has been measured.

light distribution

C0 C90 30° 30°

45° 45°

60° 60°

75° 75°

90° 90°

105° 105°

200

250

300 I ( cd/klm )

100

Lighting Guide


5.2 Cartesian diagram

The Cartesian diagram is the graphic representation of the luminous intensity in different directions. The difference with the polar diagram is that rectangular coordinates are used in the Cartesian diagram instead of polar coordinates. The scales are therefore easier to read, but the shape of the light distribution is more difficult to assess. The values are indicated in candelas per 1000 lumen (cd/klm). This value must be multiplied by the luminous flux of the used lamps. Example: 1000 cd/klm corresponds with 400 cd with a 400 lm lamp and with 1100 cd with an 1100 lm lamp. If two curves are plotted in one diagram, the distribution is different in two vertical planes.

5.3 Performance cone

The performance cone gives an indication of whether the fixture emits a narrow or a wide beam of light. The diagram also shows the illuminance at the centre of the beam Emax for different distances h between the fixture and an illuminated object. With accent lighting, the beam diameters give an impression of the size of the light spot with different distances between the fixture and an illuminated object. With downlights placed in a grid, the beam diameter is also a means to broadly assess the degree of uniformity.

If two beam angles are indicated in one diagram, this concerns a fixture with a non-rotationally symmetrical distribution. In this case, the data of two vertical planes are presented. The illuminance can be expressed in lux (lx) and this illuminance then applies to a specific lamp. However, the luminance can also be expressed in lux per 1000 lumens (lx/klm). These values must be multiplied by the luminous flux of the used lamp. Example: 1000 lx/klm corresponds with 400 lx with a 400 lm lamp and with 1100 lx with an 1100 lm lamp.

5.4 Isolux curve

The isolux lines indicate the points of equal illuminances. These curves give an idea of the illuminance on the reference plane if the fixture is suspended at a certain height.

For uplighters and wall fixtures, the stated suspension height in a room with the stated dimensions and the also-stated reflection values of ceiling, walls and floor are assumed. The same standard room is used each time to enable comparison between fixtures. Different values will be obtained in other rooms. The illuminance can be expressed in lux (lx) and this illuminance then applies to a specific lamp. However, the luminance can also be expressed in lux per 1000 lumens (lx/klm). These values must be multiplied by the luminous flux of the used lamp. Example: 1000 lx/klm corresponds with 400 lx with a 400 lm lamp and with 1100 lx with an 1100 lm lamp.

0

40

80

120

160

200

0° 45° 45° 90° 90° 135° 135° 180° 180°

C0 I ( cd/klm )

Angle gamma

Cone angle 94 °

Lamp flux 3600 lm

h Ø Emax

(m) (m) (lx)

1 2,1 670

2 4,3 167

3 6,4 74

4 8,6 42

5 10,7 27

Wall mounted vertically

5m

4

3

2

1

0

Isolux diagram floor

h = 1m

ceiling height 2.5 m

C/W/F=80/50/30%

12 lx

24 lx

18 lx

6 lx

30 lx

+2m-2m +1m-1m

Lighting Guide


5.5 Fast calculation table

fast calculation table (refl. : 80/ 80/ 30 )

2 x TC-L 18W 2G11 / 2400 lmE Lphin inlx m

room sizes in m²20 30 40 50 70 80 90 100

1,65 1 1 1 1 2 2 2 2

2,1520 1 1 1 1 2 2 2 2

2,65 1 1 1 2 2 2 2 2

1,65 2 2 2 3 4 4 4 5

2,1550 2 2 2 3 4 4 5 5

2,65 2 2 3 3 4 4 5 5

1,65 3 3 4 5 7 8 8 9

2,15100 3 4 4 5 7 8 9 10

2,65 3 4 5 6 7 8 9 10

maintenance factor : 0,8 The fast calculation table is intended for a fast estimate of the required number of fixtures. No account is taken of the shape of the room or the reflection factors of reflecting surfaces. Mounting height Lph = room height – table height. Examples: The average illuminance is E = 50 lx with 4 fixtures placed in a room of 70 m2 at suspension height Lph = 2.65 m. With 8 fixtures the average illuminance is E = 100 lx. The average illuminance increases almost proportionally with the number of fixtures, so 16 fixtures will give about 200 lx.

5.6 Utilization Factor (UF)

utilization factors / TM5

room indexreflection

C W F 0,75 1,0 1,25 1,5 2,0 2,5 3,0 4,0 5,0

70 50 20

70 30 20

70 10 20

50 50 20

50 30 20

50 10 20

30 50 20

30 30 20

30 10 20

0 0 0

BZ-class

66 70 73 75 78 80 81 83 84

63 67 70 73 76 78 79 81 83

61 65 68 70 74 76 78 80 81

65 69 72 74 76 78 79 80 81

62 67 69 71 74 76 77 79 80

60 64 67 69 72 74 76 78 79

64 68 70 72 74 75 76 78 78

62 66 68 70 72 74 75 76 77

60 64 67 68 71 73 74 76 77

59 62 65 66 69 70 71 72 73

1 1 1 1 1 1 1 1 1

SHRnom : 0,50 SHRmax : -0,899 The Utilization Factor indicates which percentage of the light reaches the working surface. The UF depends on the shape of the room (see room index) and on the reflection factors of reflecting surfaces. Example: From the table, we can read that UF = 78% with room index k = 2 and with reflection factors Ceiling 70% Wall 50% Floor 20%. With UF = 78%, the average illuminance is E = 998 lx if 10 fixtures with 4 lamps of 3200 lm are placed in a room of 100 m2. (E = 0.78 x 10 x 4 x 3200/100 = 998 lx)

Lighting Guide


5.7 Energy consumption per 100 lx per m2

Correction factors (%)

Reflectances (%)

Ceiling 80 80 50 80 80 70 70 50 30 0

Wall 50 30 30 50 30 50 30 30 30 0

Low loss TC-D 26W G24d3 Floor 30 30 30 80 10 20 20 10 10 0

PLuminaire (W) 62 Room index k

P* (W/100lx.m2) 5.3 0.6 56 48 47 54 46 54 47 45 45 39

1 77 68 66 72 65 73 66 64 63 57

1.5 94 86 82 85 80 88 82 78 77 71

2.5 109 102 96 96 92 100 95 89 88 83

3 114 108 100 99 96 104 100 93 92 87

Lamp flux = 3600 lm

Energy consumption

per 100 lux per m2

C/W/F = 70/50/20% k = 2.5

P* (W/100lx.m2) is the energy consumption per 100 lx per m2. This figure indicates the relationship between energy consumption and light output. PL (W) is the energy consumption per fixture (Luminaire), including ballast. With these two facts, it can be determined how many fixtures are required to illuminate a certain surface with a certain average illuminance and what the energy consumption will be. The values are calculated for a room with room index of k = 2.5 and reflection factors Ceiling 70% Wall 50% Floor 20% with a maintenance factor of 0.8. If k or the reflection values are different, the stated values must be corrected with the correction percentage from the correction table.

5.8 Illuminance in standard grid

Correction factors (%)

Grid (m) E (lx) Reflectances (%)

1.2 x 1.2 807 Ceiling 80 80 50 80 80 70 70 50 30 0

1.2 x 1.8 538 Wall 50 30 30 50 30 50 30 30 30 0

1.8 x 1.8 359 Floor 30 30 30 80 10 20 20 10 10 0

1.8 x 2.4 269 Room index k

1.8 x 3.0 215 0.6 56 48 47 54 46 54 47 45 45 39

2.4 x 2.4 202 1 77 68 66 72 65 73 66 64 63 57

2.4 x 3.0 161 1.5 94 86 82 85 80 88 82 78 77 71

3.0 x 3.0 129 2.5 109 102 96 96 92 100 95 89 88 83

3 114 108 100 99 96 104 100 93 92 87

Lighting level in

standard grid

The illuminance in a standard grid gives the illuminance when the fixtures are positioned in a regular grid, for instance in a suspended ceiling. The values are calculated for a room with a room index of k = 2.5 and reflection factors Ceiling 70% Wall 50% Floor 20% with a maintenance factor of 0.8. If k or the reflection values are different, the stated values can be corrected with the correction percentage from the correction table.

5.9 EULUMDAT

The photometric data of Lumiance fixtures is available as computer files in EULUMDAT format. This makes it possible to perform calculations for lighting projects with your own software. EULUMDAT data can be used in virtually any European lighting calculation software package and also in many North-American lighting calculation software packages.

Lighting Guide


5.10 Unified Glare Rating (UGR)

The UGR method relates to glare from ceiling fixtures that are placed in a regular pattern. European standard EN 12461, Lighting of Indoor Work Places, contains a table in which the maximum allowed UGR value is prescribed per type of room and per type of activity. The UGR method produces a scale figure: below 13 no glare 13 – 16 suited for accurate eye tasks 16 –19 suited for average eye tasks 19 –22 suited for moderate eye tasks 22 –28 suited for simple eye tasks above 28 not suited for work lighting

glare rating according to UGR

-ceiling 70 7070 7050 5050 5030 30

-walls 50 5030 3050 5030 3030 30

-workplane 20 2020 2020 2020 2020 20

room dimensionsX Y

viewed crosswise viewed endwise

2H 2H 15,3 15,316,7 16,715,6 15,616,9 16,917,1 17,13H 15,6 15,616,6 16,615,8 15,816,8 16,817,0 17,04H 16,1 16,117,1 17,116,4 16,417,3 17,317,5 17,56H 16,5 16,517,4 17,416,8 16,817,7 17,717,9 17,98H 16,7 16,717,6 17,617,0 17,017,9 17,918,1 18,1

12H 16,8 16,817,8 17,817,1 17,118,0 18,018,3 18,3

4H 2H 15,2 15,216,1 16,115,4 15,416,3 16,316,5 16,53H 16,5 16,517,4 17,416,8 16,817,7 17,717,9 17,94H 17,2 17,218,1 18,117,5 17,518,4 18,418,7 18,76H 17,5 17,518,2 18,217,8 17,818,6 18,618,9 18,98H 17,7 17,718,4 18,418,1 18,118,8 18,819,1 19,1

12H 18,0 18,018,7 18,718,5 18,519,1 19,119,5 19,5

8H 4H 17,3 17,318,0 18,017,7 17,718,3 18,318,7 18,76H 18,2 18,218,9 18,918,6 18,619,3 19,319,7 19,78H 18,6 18,619,2 19,219,0 19,019,6 19,620,1 20,1

12H 18,7 18,719,2 19,219,2 19,219,7 19,720,2 20,2

12H 4H 17,5 17,518,2 18,217,9 17,918,6 18,619,0 19,06H 18,4 18,419,0 19,018,8 18,819,4 19,419,9 19,98H 18,6 18,619,1 19,119,1 19,119,6 19,620,1 20,1

variation of observer position

S = 1,0H +0,2/ -0,2 +0,2/ -0,21,5H +0,4/ -0,6 +0,4/ -0,62,0H +0,8/ -1,0 +0,8/ -1,0

standard-table

correctionfor luminaire

BK04

-8,1

BK04

-8,1

correct glare indices for a total flux of 1200lm When the dimensions and the reflection factors of a room are known, the uncorrected UGR value can be read from the UGR table of a fixture. The number found must be corrected for:

The position of the observer

The actual distance between the fixtures

The actual lamps used

Lighting Guide


5.11 Söllner Diagram

glare rating for service value of illuminance (lx)class

A

1

2

3

A

B

D

E

1000

2000

750

1500

500

1000

--

750

300

500

2000

300

1000

2000

500

1000

300

500 300

1 2 3 4 5 6 7 9 10 20 30

85°

75°

65°

55°

45°

2

4

6 8

luminance curve(s)

C0-C180

Lamp type

1 x QT-ax 12 50W GY6.35

1000 lm

hsa

L (kcd/m²)

Type A

The Söllner Diagram is a graphical representation of the calculated luminance values in the area between 45 and 85 degrees to the vertical. Measures to limit discomfort glare by downlights mainly relate to this area. The slanted lines indicate the allowed limit values. The limit values depend on the quality class of the eye task and on the rated value of the illuminance.

6 Lighting of light-sensitive objects

6.1 Prevention of damage

Light can damage objects. The risk of damage from interior lighting is less than from sunlight. Sunlight can reach values of up to 100 000 lx, while the illuminance from interior lighting will mostly be below 2000 lx. Besides the amount of light produced, the spectral composition of the light is also a determining factor. In particular, blue, violet and ultraviolet light are harmful. The damage increases proportionally to the illumination time and the illuminance. A restriction of the illuminance and the lighting time are therefore the most important measures to prevent damage. Filters can be used as an additional measure.

6.2 Light fastness

The light fastness of an object can be established by subjecting samples of the materials to accelerated ageing under a strong light source, and then comparing them with materials with a known light fastness such as the „Light fastness scale‟ according to DIN 54004. Permissible illumination time with 1000 lx unfiltered daylight Class Illumination time 1 70 h 2 150 h 3 300 h 4 600 h 5 1200 h

Lighting Guide


6 2 500 h 7 5 000 h 8 10 000 h The following are highly light sensitive: Watercolours, postage stamps, prints, parchment, manuscripts, tapestries, feathers and wax. The following are fairly light sensitive: Oil paintings, wood, cork, untanned leather, bone, ivory, horn, mother of pearl and natural rubber. The following are insensitive to light: Glass, enamel, glazing and all types of stone and metal, jewellery. With some materials, the light sensitivity of specific types and qualities can differ considerably. The following are light sensitive to varying degrees: Paint, lacquer, ink, plastic, paper, textile and photographic products.

6.3 Advised maximum illuminance

Highly light sensitive 50 lx Fairly light sensitive 150 lx Slightly light sensitive 300 lx

6.4 Filters

UV radiation can be filtered out with UV filters. This reduces the harm caused by light sources. To make a comparison between different lighting systems possible, the operation of light source + filter is given with respect to unfiltered daylight. An extension factor of roughly 4 with respect to unfiltered daylight is the highest achievable value with an artificial light source in combination with a UV filter. A higher extension factor can only be achieved by also filtering out the blue part of the visible light. This naturally has an unfavourable effect on the colour reproduction and the light output.

6.5 Calculation of the allowed illumination time

T = k.t.1000/E Where: T = the allowed illumination time in hours k = extension factor t = permissible time in hours at 1000 lx, unfiltered daylight E = illuminance (lx) Example: newsprint in light fastness class I In sunlight (100 000 lx) and extension factor 1, the permissible illumination time is 1 x 70 x 1000/100 000 = 0.7 hour. In halogen light (200 lux) and extension factor 2.3, the permissible illumination time is 2.3 x 70 x 1000/200 = 805 hours. In UV-filtered halogen light (200 lux) and extension factor 3.5, the permissible illumination time is 3.5 x 70 x 1000/200 = 1225 hours.

6.6 Damage prevention with Lumiance products

Fixtures for incandescent lamps, extension factor 2.7 – 3.5 The extension factor of incandescent lamps with respect to unfiltered daylight is 2.7. By dimming, this factor can be increased to 3.5. Here, the light colour changes from warm white to yellow. If there is further dimming, the light colour goes to orange and then to red. From a conservation viewpoint, lighting with red light is preferred.

Lighting Guide


Fixtures for halogen reflector lamps, extension factor 2.5 – 3.5 Lumiance recommends that only halogen reflector lamps with a front glass be used. With lamps with a front glass of borosilicate glass, the extension factor is 2.5 with respect to unfiltered daylight. QR-CB “UV-stop” lamps can be used in all Lumiance fixtures for QR-CB. The extension factor is approx. 3.5 with respect to unfiltered daylight. Fixtures for halogen capsules, extension factor 2.5 – 3.5 Fixtures for QT halogen lamps are supplied as standard with a front glass. In this case, the extension factor is 2.5 with respect to unfiltered daylight. With “UV-stop” QT lamps, the same effect is achieved as with a normal QT lamp in combination with a UV filter. The extension factor is approx. 3.5 with respect to unfiltered daylight. Fixtures for high-pressure metal-halide, extension factor 1.1 - 2.1 Fixtures for high-pressure metal-halide lamps are supplied standard with a safety glass with an extension factor of 1.1 with respect to unfiltered daylight. UV filters can be supplied for these fixtures. The extension factor of these filters is 2.1 with respect to unfiltered daylight. Fixtures for high-pressure sodium lamps, extension factor 4 High-pressure sodium lamps do not produce UV radiation. These lamps can be used without a filter. The extension factor is approx. 4 with respect to unfiltered daylight. Fixtures for fluorescent lamps, extension factor 1.9 - 2.7 With fluorescent lamps, the extension factor depends on the light colour (cool white approx. 1.9, warm white approx. 2.7).

7 Lighting terminology

7.1 Light

The human eye is sensitive for electromagnetic radiation with a wavelength between 380 and 720 nm. If the wavelength is less than 380 nm, it is called ultraviolet light; if the wavelength is higher than 720 nm, it is called infra-red light (thermal radiation).

7.2 Luminous flux

Phi (lm) The luminous flux is the amount of visible electromagnetic radiation, measured in lumens (lm). The lamp manufacturers specify the rated luminous flux of their lamps. The luminous flux is expressed in lumens (lm).

Luminous flux is measured in an Ulbricht sphere.

Lighting Guide


Luminous intensity

I = Phi/sr (cd) The luminous intensity always relates to a certain direction and is connected with the operation of reflectors and diffusers. The luminous intensity is the luminous flux radiated in a certain solid angle (sr), divided by this solid angle. The luminous intensity is expressed in candelas (cd).

Luminous intensity distributions of luminaires are measured in a photometer.

7.3 Illuminance

E = Phi/A (lx) The illuminance refers to the incidence of the light flux on a surface, per unit of surface. The illuminance is expressed in lux (lx). Full moon 0.1 lx Emergency lighting 1 lx Street lighting 10 lx Winter day 10 000 lx Summer day 100 000 lx

lluminance is measured with a lux meter.

light distribution

C0 C90 30° 30°

45° 45°

60° 60°

75° 75°

90° 90°

105° 105°

200

250

300 I ( cd/klm )

100

C

Lighting Guide


7.4 Luminance

L = E/A (cd/m2) Luminance indicates the degree of brightness with which the human eye perceives a light source or an illuminated surface. The luminance is expressed in candela per square meter (cd/m2).

Luminance is measured with a luminance meter.

7.5 Colour temperature

Tc (K) Temperature of a certain object (black body) that radiates light of the same type of colour as the given light source. Incandescent lamps have a colour temperature of 2700 K, but halogen lamps have a higher colour temperature. A higher colour temperature is perceived as a „cooler‟ light (more blue). The colour temperature is expressed in Kelvin (K). Candle 1 900 K Incandescent lamp 2 700 K Halogen lamp 3 000 K Direct sunlight 6 000 K Daylight with cloudy sky 7 000 K Daylight with clear sky 20 000 K

1 000 000 000 cd/m2 10 000 cd/m

2 10 000 000 cd/m

2

Lighting Guide


7.6 Colour rendering index

Ra (%) The colour rendering index indicates to what degree the colour rendering of a light source deviates from that of an incandescent lamp. With Ra(8), the colour shift of eight reference colours is measured as a percentage. The Ra is the average of these eight values. A colour rendering index of 100 to 90 is good, 90 to 80 are less good and lamps with an Ra below 80 are unsuited for applications where colour rendering is important.

Lamps are divided into quality classes: Class Ra 1a 90 to 100 1b 80 to 89 2a 70 to 79 2b 60 to 69 3 40 to 50 4 20 to 39

7.7 Uniformity ratio

G = Emin/Egem (%) The uniformity ratio is the ratio between the minimum illuminance and the average illuminance on a surface. This figure indicates the degree of “eveness”. E = 1 indicates complete uniformity.

7.8 SHR

The SHR (Spacing to Height Ratio) is the number that indicates the maximum that the fixtures may be apart to still achieve sufficient uniformity. The number is given as the ratio between the distance between the fixtures and the height between the fixtures and the working plane. As a result, the same number applies to every suspension height.

7.9 Room index k

The room index is the ratio between the surface of the working plane and the half surface of the adjacent walls. This indicates whether a room is narrow and high, or low and wide. This influences the amount of light that is reflected to the working plane from the walls. k = a . b / ( h . (a + b)) a = length of the room b = width of the room h = height between the lighting fixtures and the working plane.

7.10 Maintenance factor

As a result of contamination of the lamp and fixture, plus degradation of the lamp, the illuminance reduces in the course of time. This must be taken into account during the lighting design. With normal maintenance, the maintenance factor should be 0.8 or higher.

Lighting Guide


7.11 Specific luminous flux

The specific luminous flux indicates how efficiently a lamp converts electrical energy to light that is visible for human beings. This is indicated in lumens per Watt (lm/W).

7.12 Light Output Ratio (LOR)

LOR (%) The luminaire efficiency indicates how well a fixture uses the luminous flux of the lamp. This is indicated as the ratio between the luminous flux of a fixture and the light source of the „bare‟ lamp, expressed as a percentage.

7.13 Utilization Factor (UF)

UF (%) The utilization factor indicates how well a lighting installation uses the luminous flux of the lamps. This is indicated as the ratio between the luminous flux that reaches the working plane and the light source of the „bare‟ lamps, expressed as a percentage.

light_gd1

Documents

indoor work

permissible

allowed illumination

limit discomfort

pressure sodium

fast calculation

colour rendering

halogen reflector