18675256 lighting handbook licht 01 lighting with artificial light

licht.wissen 01Lighting with Artificial Light

licht.wissen 01 Lighting with Artificial Light

The medium of light 1From nature’s light ... to artificial lighting 4The physics of light 6The physiology of light 9

The language of lighting technology 12Quality features in lighting 15Lighting level –maintained illuminance and luminance 16Glare limitation – direct glare 18Glare limitation – reflected glare 20Harmonious distribution of brightness 22Direction of light and modelling 24Light colour 26Colour rendering 28

Light generation by thermal radiators,discharge lamps and LEDs 30Lamps 34

Luminaires – general requirementsand lighting characteristics 38Luminaires – electrical characteristics, ballasts 40Luminaires – operating devices, regulation, control, BUS systems 44Review of luminaires 48

Lighting planning 50Measuring lighting systems 52Lighting costs 54Energy-efficient lighting 56Lighting and the environment 58

Standards, literature 59licht.de publications 60Imprint and acknowledgements for photographs 61

Content

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[01] “The Artist’s Sister with a Candle” (1847),Adolf Menzel (1815 – 1905), Neue Pinakothek,Munich, Germany

[02] “Café Terrace at Night” (1888), VincentVan Gogh (1853 – 1890), Rijksmuseum Kröller-Müller, Otterlo, Netherlands

[03] “The Sleepwalker” (1927), René Magritte(1898 – 1967), privately owned

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Booklet 1 of the licht.de series of publica-tions is intended for all those who want todelve into the topic of light and lighting orwish to familiarize themselves with the ba-sics of lighting technology. It also forms theintroduction to a series of publications de-signed to provide useful information onlighting applications for all those involved inplanning or decision-making in the field oflighting.

One of the principal objectives of all licht.depublications is to promote awareness of amedium which we generally take for grant-ed and use without a second thought. It isonly when we get involved in “making” light,in creating artificial lighting systems, thatthings get more difficult, more technical.

Effective lighting solutions naturally call forexpertise on the part of the lighting de-signer. But a certain amount of basicknowledge is also required by the client, ifonly to facilitate discussion on “good light-ing” with the experts. This publication andthe other booklets in the series are de-signed to convey the key knowledge andinformation about light, lamps and lumi-naires needed to meet those requirements.

Light is not viewed in these booklets assimply a physical phenomenon; it is consid-ered in all its implications for human life. Asthe radiation that makes visual contact pos-sible, light plays a primarily physiologicalrole in our lives by influencing our visualperformance; it also has a psychologicalimpact, however, helping to define oursense of wellbeing.

Furthermore, light has a chronobiologicaleffect on the human organism. We knowtoday that the retina of the eye has a spe-cial receptor which regulates such things asthe sleep hormone melatonin. Light thushelps set and synchronize our “biologicalclock”, the circadian rhythm that regulatesactive and passive phases of biological ac-tivity according to the time of day and year.

So the booklets published by licht.de notonly set out to provide information aboutthe physics of light; they also look at thephysiological and psychological impact of“good lighting” and provide ideas and ad-vice on the correct way to harness light fordifferent applications – from street lightingto lighting for industry, schools and offices,to lighting for the home.


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The medium of lightLight has always held a special fascination – in art and architecture too. Brightness and shadow, colour andcontrast shape the mood and atmosphere of a room or space. They even help define fleeting moments.

[04] Coloured light sets accents.

Most of the information we receive aboutour surroundings is provided by our eyes.We live in a visual world. The eye is themost important sense organ in the humanbody, handling around 80% of all incominginformation. Without light, that would be im-possible – light is the medium that makesvisual perception possible.

Insufficient light or darkness gives rise to asense of insecurity. We lack information, welose vital bearings. Artificial lighting duringthe hours of darkness makes us feel safe.

So light not only enables us to see; it alsoaffects our mood and sense of wellbeing.

Lighting level and light colour, modellingand switches from light to dark impact onmomentary sensations and determine therhythm of our lives.

In sunlight, for instance, illuminance isabout 100,000 lux. In the shade of a tree itis around 10,000 lux, while on a moonlitnight it is 0.2 lux, and even less by starlight.

People nowadays spend most of the dayindoors – in illuminances between 50 and500 lux. Light sets the rhythm of our biolog-ical clock but it needs to be relatively in-tense to have an effect on the circadiansystem (� 1,000 lux), so for most of thetime we live in “chronobiological darkness”.The consequences are troubled sleep, lackof energy, irritability, even severe depres-sion.

As we said above, light is life. Good lightingis important for seeing the world around us.What we want to see needs to be illumi-nated. Good lighting also affects the waywe feel, however, and thus helps shape ourquality of life.

Around 300,000 years ago, man began touse fire as a source of warmth and light.The glowing flame enabled people to live incaves where the rays of the sun never pen-etrated.

The magnificent drawings in the Altamiracave – artworks dating back some 15,000years – can only have been executed in arti-ficial light. The light of campfires, of kindlingtorches and oil and tallow lamps radicallychanged the way prehistoric man lived.

But light was not only used in enclosedspaces. It was also harnessed for applica-tions outdoors. Around 260 BC, the Pharosof Alexandria was built, and evidence from378 AD suggests there were “lights in thestreets” of the ancient city of Antioch.

Ornamental and functional holders for theprecious light-giving flame appear at a veryearly stage in the historical record. But theliquid-fuel lamps used for thousands ofyears underwent no really major improve-ment until Aimé Argand‘s invention of thecentral burner in 1783.

That same year, a process developed byDutchman Jan Pieter Minckelaers enabledgas to be extracted from coal for street-lamps. Almost simultaneously, experimentsstarted on electric arc lamps – fuelling research which acquired practical signifi-cance in 1866 when Werner Siemens suc-ceeded in generating electricity economi-cally with the help of the dynamo. But thereal dawn of the age of electric light camein 1879, with Thomas A. Edison’s “re-invention” and technological application ofthe incandescent lamp invented 25 yearsearlier by the German clock-maker JohannHeinrich Goebel.

With each new light source – from campfireand kindling to candle and electric lightbulb – “luminaires” were developed tohouse and harness the new “lamps”. In re-cent decades, lamp and luminaire develop-ment has been particularly dynamic, draw-ing on the latest technologies, new opticalsystems and new materials while at thesame time maximising economic efficiencyand minimising environmental impact.


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From nature‘s light ... to artificial lightingLight is life. The relationship between light and life cannot be stated more simply than that.

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[05] The light of the sun determines the pulseof life and the changing alternation of day andnight throughout the year.

[06] The light of the moon and stars has only1/500,000th of the intensity of sunlight.

[07] In a rainbow, raindrops act like prisms.

[08] Advances in the development of electricdischarge lamps, combined with modern lumi-naires, has led to high-performance lighting sys-tems.

[09] For the majority of people today, life with-out artificial lighting would be unimaginable.

[10] For more than 2,000 years, artificial light-ing has illuminated the night and provided secu-rity and orientation for human beings.

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For example, since no connection could bediscerned between a flame and the object it rendered visible, it was at one time sup-posed that “visual rays” were projected bythe eyes and reflected back by the object.Of course, if this theory were true, wewould be able to see in the dark ...

In 1675, by observing the innermost of thefour large moons of Jupiter discovered byGalileo, O. Römer was able to estimate thespeed of light at 2.3 x 108 m/s.

A more precise measurement was obtainedusing an experimental array devised byLéon Foucault: 2.98 x 108. The speed oflight in empty space and in air is generally rounded up to 3 x 108 m/s or 300,000 km/s.

This means that light takes around 1.3 sec-onds to travel from the Moon to the Earthand about 81⁄3 minutes to reach the Earthfrom the Sun. Light takes 4.3 years toreach our planet from the fixed star Alpha inCentaurus, about 2,500,000 years from theAndromeda nebula and more than 5 billionyears from the most distant spiral nebulae.

Different theories of light enable us to de-scribe observed regularities and effects.

The corpuscular or particle theory of light,according to which units of energy (quanta)are propagated at the speed of light in astraight line from the light source, was pro-posed by Isaac Newton. The wave theoryof light, which suggests that light moves ina similar way to sound, was put forward by Christiaan Huygens. For more than ahundred years, scientists could not agreewhich theory was correct. Today, both con-cepts are used to explain the properties oflight: light is the visible part of electromag-netic radiation, which is made up of oscillat-ing quanta of energy.

It was Newton again who discovered that

white light contains colours. When a narrowbeam of light is directed onto a glass prismand the emerging rays are projected onto awhite surface, the coloured spectrum oflight becomes visible.

In a further experiment, Newton directedthe coloured rays onto a second prism,from which white light once again ap-peared. This was the proof that white sun-light is the sum of all the colours of thespectrum.

In 1822, Augustin Fresnel succeeded in determining the wavelength of light andshowing that each spectral colour has aspecific wavelength. His statement that“light brought to light creates darkness”sums up his realization that light rays of thesame wavelength cancel each other outwhen brought together in correspondingphase positions.

Max Planck expressed the quantum theoryin the formula:

E = h · �

The energy E of an energy quantum (of radiation) is proportional to its frequency �,multiplied by a constant h (Planck‘s quan-tum of action).


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The physics of lightMan has always been fascinated by light and has constantly striven to unravel its mysteries. History has producedvarious theories that today strike us as comical but were seriously propounded in their time.

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[14] If the artificial light of a fluorescent lamp is split up, the individual spectral colours arerendered to a greater or lesser extent, depend-ing on the type of lamp.

[15] Both the particle and the wave theory oflight are used to provide a succinct descriptionof the effects of light and how these conform tonatural laws.

[11] Within the wide range of electromagneticradiation, visible light constitutes only a narrow band.

[12] With the aid of a prism, “white” sunlightcan be split up into its spectral colours.

[13] The prism combines the spectral coloursto form white light. Sunlight is the combinationof all the colours of its spectrum.

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1211

long waves

medium wavesshort wavesultra-short waves

television

radarinfrared rayslightultraviolet rays

x-rays

gamma rays

cosmic radiation

The Earth‘s atmosphere allows visible, ultra-violet and infrared radiation to pass throughin such a way that organic life is possible.

Wavelengths are measured in nanometres(nm) =10-9 m = 10-7 cm. One nanometre isa ten-millionth of a centimetre.

Light is the relatively narrow band of elec-tromagnetic radiation to which the eye issensitive. The light spectrum extends from380 nm (violet) to 780 nm (red).

Each wavelength has a distinct colour appearance, and from short-wave violetthrough blue, green, green-yellow, orangeup to long-wave red, the spectrum of sunlight exhibits a continuous sequence.

Coloured objects only appear coloured iftheir colours are present in the spectrum ofthe light source. This is the case, for exam-ple, with the sun, incandescent lamps andfluorescent lamps with very good colourrendering properties.

Above and below the visible band of the radiation spectrum lie the infrared (IR) andultraviolet (UV) ranges.

The IR range encompasses wavelengthsfrom 780 nm to 1 nm and is not visible tothe eye. Only where it encounters an objectis the radiation absorbed and transformedinto heat. Without this heat radiation fromthe sun, the Earth would be a frozen planet.Today, thanks to solar technology, IR radia-tion has become important both techno-logically and ecologically as an alternativeenergy source.

For life on Earth, the right amount of radia-tion in the UV range is important. This ra-diation is classed according to its biologicalimpact as follows:

> UV-A (315 to 380 nm), suntan, solaria;> UV-B (280 to 315 nm), erythema (reddening of the skin), sunburn;> UV-C (100 to 280 nm), cell destruction,bactericidal lamps.


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[16] A prism makes the colour spectrum oflight visible.

[17+18] Compared with its appearance indaylight, a red rose looks unnatural under themonochromatic yellow light of a low-pressuresodium vapour lamp. This is because the spectrum of such light contains no red, blue or green, so those colours are not rendered.

Despite the positive effects of ultraviolet radiation – e.g. UV-B for vitamin D synthe-sis – too much can cause damage. Theozone layer of the atmosphere protects usfrom harmful UV radiation, particularly fromUV-C. If this layer becomes depleted(ozone gap), it can have negative conse-quences for life on Earth.

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The image-producing optics consist of thecornea, the lens and the intervening aque-ous humour. Alteration of the focal lengthneeded for accurate focusing on objects atvarying distances is effected by an adjust-ment of the curvature of the refractive surfaces of the lens. With age, this accom-modative capacity decreases, due to ahardening of the lens tissue.

With its variable central opening – the pupil– the iris in front of the lens functions as anadjustable diaphragm and can regulate theincident luminous flux within a range of1:16. At the same time, it improves thedepth of field. The inner eye is filled with aclear, transparent mass, the vitreous hu-mour.

The retina on the inner wall of the eye is the“projection screen”. It is lined with some130 million visual cells. Close to the opticalaxis of the eye there is a small depression,

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[19] The eye is a sensory organ with extraordi-nary capabilities. Just a few highly sensitive“components” complement each other to forma remarkable visual instrument:

a corneab lensc pupild irise suspensory ligaments/ciliary musclesf vitreous humourg sclerah retinai blind spotj foveak optic nerve

[20] Curve of relative spectral sensitivity forday vision (cones) V(�) and night vision (rods)V‘(�).

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The physiology of lightThe optical components of the eye can be compared to a photographic camera.

the fovea, in which the visual cells for dayand colour vision are concentrated. This isthe region of maximum visual acuity.

Depending on the level of brightness (lumi-nance), two types of visual cell – cones androds – are involved in the visual process.

The 120 million rods are highly sensitive tobrightness but relatively insensitive tocolour. They are therefore most active atlow luminance levels (night vision); theirmaximum spectral sensitivity lies in theblue-green region at 507 nm.

The 7 million or so cones are the more sen-sitive receptors for colour. These take overat higher levels of luminance to provide dayvision. Their maximum spectral sensitivitylies in the yellow-green range at 555 nm.There are three types of cone, each with adifferent spectral sensitivity (red, green,blue), which combine to create an impres-sion of colour. This is the basis of colour vision.

400 500 600 700 800Wavelength (nm)

Sp

ectr

al li

ght

sens

itivi

ty V

(�)

1,0

0,8

0,6

0,4

0,2

The ability of the eye to adjust to higher orlower levels of luminance is termed adapta-tion. The adaptive capacity of the eye ex-tends over a luminance ratio of 1:10 billion.The pupils control the luminous flux enter-ing the eyes within a range of only 1:16,while the “parallel switching” of the ganglioncells enables the eye to adjust to the farwider range.

The state of adaptation affects visual per-formance at any moment, so that thehigher the level of lighting, the more visualperformance will be improved and visual errors minimized. The adaptive process andhence adaptation time depend on the lumi-nance at the beginning and end of anychange in brightness.

Dark adaptation takes longer than lightadaptation. The eye needs about 30 min-utes to adjust to darkness outdoors at nightafter the higher lighting level of a workroom.Only a few seconds are required, however,for adaptation to brighter conditions.

Sensitivity to shapes and visual acuity areprerequisites for identification of details.

Visual acuity depends not only on the stateof adaptation but also on the resolvingpower of the retina and the quality of theoptical image. Two points can just be per-ceived as separate when their images onthe retina are such that the image of eachpoint lies on its own cone with another “unstimulated” cone between them.

Inadequate visual acuity can be due to eyedefects, such as short- or long-sighted-ness, insufficient contrast, insufficient illumi-nance.

Four minimum requirements need to bemet to permit perception and identifica-tion:

1. A minimum luminance is necessary toenable objects to be seen (adaptation lumi-nance). Objects that can be identified in de-tail easily during the day become indistinctat twilight and are no longer perceptible indarkness.

2. For an object to be identified, thereneeds to be a difference between its bright-ness and the brightness of the immediate

surroundings (minimum contrast). Usuallythis is simultaneously a colour contrast anda luminance contrast.

3. Objects need to be of a minimum size.

4. Perception requires a minimum time. Abullet, for instance, moves much too fast.Wheels turning slowly can be made out indetail but become blurred when spinning athigher velocities. The challenge for lightingtechnology is to create good visual condi-tions by drawing on our knowledge of thephysiological and optical properties of theeye – e.g. by achieving high luminance andan even distribution of luminance within thevisual field.


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2

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[21] Schematic structure of the retina:1 ganglion cells2 bipolar cells3 rods4 cones

[22– 24] Adaptation of the eye: On coming outof a bright room and entering a dark one, we atfirst see “nothing” – only after a certain period oftime do objects start to appear out of the dark-ness.

[25] Where two points 0.3 mm apart are iden-tified from a distance of 2 m, visual acuity is 2. If we need to be 1 m from the visual object tomake out the two points, visual acuity is 1.

[26– 32] Four requirements need to be met topermit perception and identification: a minimumluminance, minimum contrast, minimum size,minimum time

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Luminous flux �

is the rate at which light is emitted by a lamp. It is measured in lu-mens (lm). Ratings are found in lamp manufacturers‘ lists.

The luminous flux of a 100 W incandescent lamp is around 1,380lm, that of a 20 W compact fluorescent lamp with built-in elec-tronic ballast around 1,200 lm.

Luminous intensity I

is the amount of luminous flux radiating in a particular direction. It ismeasured in candelas (cd).

The way the luminous intensity of reflector lamps and luminaires isdistributed is indicated by curves on a graph. These are known asintensity distribution curves (IDCs).

To permit comparison between different luminaires, IDCs usuallyshow 1,000 lm (= 1 klm) curves.

This is indicated in the IDC by the reference cd/klm. The form ofpresentation is normally a polar diagram, although xy graphs areoften found for floodlights.


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The language of lighting technology

� �

33 35

34 36

Illuminance E

is measured in lux (lx) on horizontal and vertical planes. Illuminanceindicates the amount of luminous flux from a light source falling on agiven surface.

Luminance L

indicates the brightness of an illuminated or luminous surface asperceived by the human eye. It is measured in units of luminousintensity per unit area (cd/m2). For lamps, the “handier” unit ofmeasurement cd/cm2 is used. Luminance describes the physio-logical effect of light on the eye; in exterior lighting it is an impor-tant value for planning. With fully diffuse reflecting surfaces – ofthe kind often found in interiors – luminance in cd/m2 can be cal-culated from the illuminance E in lux and the reflectance �:

L = � · E�

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L

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Luminous efficacy �

is the luminous flux of a lamp in relation toits power consumption. Luminous efficacyis expressed in lumens per watt (lm/W).

For example, an incandescent lamp pro-duces approx. 14 lm/W, a 20 W compactfluorescent lamp with built-in EB approx. 60 lm/W.

Light output ratio �LB

is the ratio of the radiant luminous flux of aluminaire to the luminous flux of the fittedlamp. It is measured in controlled operatingconditions

Glare

is annoying. It can be caused directly by lu-minaires or indirectly by reflective surfaces.

Glare depends on the luminance and sizeof the light source, its position in relation tothe observer and the brightness of the sur-roundings and background. Glare shouldbe minimized by taking care over luminairearrangement and shielding, and taking ac-count of reflectance when choosing coloursand surface structures for walls, ceiling andfloor. Glare cannot be avoided altogether.

It is especially important to avoid directglare in street lighting as this affects roadsafety.

Where VDU workplaces are present, specialprecautions must be taken to avoid re-flected glare.

Reflectance �

indicates the percentage of luminous fluxreflected by a surface. It is an importantfactor for calculating interior lighting.

Dark surfaces call for high illuminance,lighter surfaces require a lower illuminancelevel to create the same impression ofbrightness.

In street lighting, the three-dimensional dis-tribution of the reflected light caused by di-rectional reflectance (e.g. of a worn roadsurface) is an important planning factor.

Maintained illuminance E_

m and luminance L

_m

depend on the visual task to be performed.Illuminance values for interior lighting areset out in the harmonized European stan-dard DIN EN 12464-1. Values for “Outdoorworkplaces” are contained in DIN EN124564-2.

Illuminance and luminance values for streetlighting are stipulated in DIN EN 13201-2.Sports facility lighting is covered by anotherharmonized European standard, DIN EN12193.

Maintained values are the values belowwhich the local average values of the light-ing installation are not allowed to fall.

Uniformity

of illuminance or luminance is another qual-ity feature. It is expressed as the ratio ofminimum to mean illuminance (g1 = Emin / E

_)

or, in street lighting, as the ratio of minimumto mean luminance (U0 = Lmin / L

_).

In certain applications, the ratio of minimumto maximum illuminance g2 = Emin /Emax isimportant.

Maintenance factor

With increasing length of service, illumi-nance decreases as a result of ageing andsoiling of lamps, luminaires and room sur-faces.

Under the harmonized European standards,designer and operator need to agree andrecord maintenance factors defining the illuminance and luminance required on in-stallation to ensure the values which needto be maintained.

Where this is not possible, a maintenancefactor of 0.67 is recommended for interiorssubject to normal ageing and soiling; thismay drop as low as 0.5 for rooms subjectto special soiling. Maintained value andmaintenance factor define the value re-quired on installation: maintained value =maintenance factor x value on installation.


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Just as the nature of occupational andrecreational activities differs – e.g. reading abook, assembling miniature electronic com-ponents, executing technical drawings, run-ning colour checks in a printing works, etc.– so too do the requirements presented byvisual tasks. And those requirements definethe quality criteria a lighting system needsto meet.

Careful planning and execution are pre-requisites for good quality artificial lighting.This is what specific quality features deter-mine:

> lighting level – brightness,

> glare limitation – vision undisturbed by either direct or indirect glare,

> harmonious distribution of brightness –an even balance of luminance,

> light colour – the colour appearance oflamps, and in combination with

> colour rendering – correct recognitionand differentiation of colours and room ambience,

> direction of light and

> modelling – identification of three-dimen-sional form and surface textures.

Depending on the use and appearance of aroom, these quality features can be givendifferent weightings. The emphasis may beon:

> visual performance, which is affected bylighting level and glare limitation,

> visual comfort, which is affected bycolour rendering and harmonious bright-ness distribution,

> visual ambience, which is affected bylight colour, direction of light and modelling

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[41] Lighting quality features are interrelated.

Quality features in lightingTaken together, quality features determine the quality of lighting. So it is not enough to design a lighting system onthe basis of only one feature, e.g. illuminance.

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Lighting level is influenced by illuminanceand the reflective properties of the surfacesilluminated. It is a defining factor of visualperformance.

Some examples of reflectance: > white walls up to 85 % > light-coloured wood panelling up to 50 %> red bricks up to 25 %.

The lower the reflectance and the more dif-ficult the visual task, the higher the illumi-nance needs to be.

Maintained illuminance

Maintained illuminance is the value belowwhich the average illuminance on the as-sessment plane is not allowed to fall. Withincreasing length of service, illuminance isreduced owing to ageing and soiling oflamps, luminaires and room surfaces. Tocompensate for this, a new system needsto be designed for higher illuminance (valueon installation).

The reduction is taken into consideration bya maintenance factor: maintained illumi-nance = maintenance factor x illuminanceon installation.

Maintenance factor

The maintenance factor depends on themaintenance characteristics of lamps andluminaire, the degree of exposure to dustand soiling in the room or surroundings aswell as on the maintenance programmeand maintenance schedule. In most cases,not enough is known at the lighting plan-ning stage about the factors that will laterimpact on illuminance, so where a mainte-nance interval of three years is defined, themaintenance factor required is 0.67 forclean rooms and as low as 0.5 for rooms

subject to special soiling (e.g. smokingrooms).

The surface on which the illuminance is re-alised is normally taken as the evaluationplane. Recommended heights: 0.75 mabove floor level for office workplaces, max.0.1 m in circulation areas. The maintainedilluminance values required for indoor work-places are set out in DIN EN 12464-1 fordifferent types of interior, task or activity.For outdoor workplaces, the values re-quired are stipulated in DIN EN 12464-2.

Examples:Circulation areas 100 lxOffice 500 lxOperating cavity 100,000 lx

For sports lighting, reference planes (atfloor/ground level) and illuminance require-ments are set out for different types ofsport in the harmonized European standardDIN EN 12193. Illuminance is the variableused for planning interior lighting because itis easy to measure and fairly straightfor-ward to compute.

Luminance

Determining luminance L (measured incd/m2) entails more complex planning andmeasurement.

For street lighting, luminance is an essentialcriterion for assessing the quality of a light-ing system. What motorists see is the lightreflected in their direction from the per-ceived road surface (the material-depen-dent and directional luminance).


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Lighting level –Maintained illuminance and luminanceFor interiors and for certain exterior lighting applications, maintained illuminance is stipulated by standards. Lumi-nance is a quality feature of e.g. street lighting.

Since the reflectance of road surfaces isstandardized and a single observation pointhas been defined as standard, luminance isthe variable normally used for planningstreet lighting.

The illumination of a street depends on theluminous flux of the lamps, the intensity distribution of the luminaires, the geometryof the lighting system and the reflectance

of the road surface. The quality features ofstreet lighting are listed in DIN EN 13201-2.

Recommended values:Local service street 7.5 lxMain thoroughfare 1.5 cd/m2

Car park 15 lx

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[42] Reflectance � of walls, floor, ceiling and working plane recommended in DIN EN12464-1.

[43] In street lighting, luminance is the keyquantity: road users perceive the light reflectedby the road surface as luminance.

[44] Value on installation (initial value) andmaintained value

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Glare causes discomfort (psychologicalglare) and can also lead to a marked reduc-tion in visual performance (physiologicalglare); it should therefore be limited.

The TI method in street lighting

Every motorist is aware of the dangers ofglare in street lighting and its implicationsfor road safety. Effective limitation of physi-ological glare is therefore an important requirement for good street lighting.

The method used to limit glare in streetlighting is based on the physiological effectof glare and demonstrates the extent towhich glare reduces the eye‘s threshold ofperception.

In outdoor lighting, physiological glare is as-sessed by the TI (Threshold Increment)method.

The TI value shows in percent how muchthe visual threshold is raised as a result ofglare. The visual threshold is the differencein luminance required for an object to bejust perceptible against its background.

Example:Where street lighting is glare-free, the eyeadapts to the average luminance of theroad L. A visual object on the roadway isjust perceptible where its luminance con-trast in relation to its surroundings is L0

(threshold value). Where dazzling lightsources occur in the visual field, however,diffuse light enters the eye and covers theretina like a veil. Although the average lumi-

nance of the road remains unchanged, thisadditional “veiling luminance” Ls causes theeye to adapt to a higher level L + LS. An object with a luminance contrast of L0 inrelation to its surroundings is then no longervisible.

Where glare occurs, luminance contrastneeds to be raised to LBL for an object tobe perceptible. On a road of known aver-age roadway luminance L, the increment LBL – L0 can be used as a yardstick forthe impact of glare. The percentage rise inthreshold values TI (Threshold Increment)from L0 auf LBL has been adopted as ameasure of physiological glare and is calcu-lated on the basis of the following formula:

The UGR method in indoor lighting

In indoor lighting, psychological glare israted by the standardized UGR (UnifiedGlare Rating) method. This is based on aformula which takes account of all the lumi-naires in a lighting system that contribute to a sensation of glare. Glare is assessedusing UGR tables, which are based on theUGR formula and are available from lumi-naire manufacturers.


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Glare limitation – direct glareDirect glare is caused by excessive luminance – e.g. from unsuitable or inappropriately positioned luminaires or fromunshielded general-diffuse lamps.

UGR = 8 log0,25 L2 �

Lb � p2

TI=

LBL - L0· 100

% Lo

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[45] The UGR method takes account of all theluminaires in a lighting system which add to thesensation of brightness as well as the bright-ness of walls and ceilings; it produces a UGRindex.

[46] Assessment of physiological glare by theTI method: luminance contrast L as a functionof adaptation luminance L. Where glare occurs,the luminance contrast needs to be raised to LBL for the visual object to be perceptible.

To avoid glare due to bright light sources, lamps should beshielded. The minimum shielding angles set out below need tobe observed for the lamp luminance values stated.

Lamp luminance cd/m2 Minimum shielding angle �

20,000 to 50,000 15°

50,000 to 500,000 20°

� 500,000 30°

Shielding against glare

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VDUs Mean luminance of luminaires and surfaces which reflect on screens

Positive display VDUs

Negative display VDUs with � 1,000 cd/m2

high-grade anti-reflective systemEvidence of test certificate required

Negative display VDUs with � 200 cd/m2

lower-grade anti-reflective system

Reflected glare refers to the disturbing re-flections of lamps, luminaires or bright win-dows found on reflective or glossy surfacessuch as art paper, computer monitors orwet asphalt roads.

Reflected glare can be limited by the rightchoice and appropriate arrangement oflamps and luminaires.

Reflected glare on shiny horizontal surfaces(reading matter and writing paper) is as-sessed using the contrast rendering factorCRF, which can be calculated by specialsoftware. For normal office work, a mini-mum CRF of 0.7 is enough; only work in-volving high-gloss materials calls for ahigher factor.

Reflected glare on VDU screens is the mostcommon cause of complaint. It is effectivelyavoided where monitors are arranged insuch a way that bright surfaces such aswindows, luminaires and light-colouredwalls cannot be reflected on screens.Where such an arrangement is not possi-ble, the luminance of the surfaces reflectedon screens needs to be reduced.

For luminaires, luminance limits have beendefined (see table below). These depend on the anti-glare system of the computermonitor and apply to all emission anglesabove 65° to the vertical all around the ver-tical axis.


20

Glare limitation – reflected glareReflected glare causes the same kind of disturbance as direct glare and, above all, reduces the contrasts neededfor trouble-free vision.

21

[50+51] Depending on the class of VDU, the mean luminance of luminaires which couldcast reflections onto the screen needs to be limited to 200 cd/m2 or 1,000 cd/m2 above thecritical beam angle of � = 65° (at 15° intervals all round the vertical axis).

[48] Reflected glare, caused by veiling reflec-tions on the surface of the object being viewed,is disturbing and thus makes for poor visualconditions.

[49] Reflections on monitors are particularlyannoying. Where direct luminaires could cast reflections onto screens, their luminance needsto be limited.

50

48 49

51

Marked differences in luminance in the fieldof vision impair visual performance andcause discomfort, so they need to beavoided. This applies as much outdoors,e.g. in sports facilities or street lighting, as itdoes in interior lighting.

The luminance of a desktop, for example,should be no less than one third of the lu-minance of the document.

The same ratio is recommended betweenthe luminance of the work surface and thatof other areas further away in the room. The ratio of visual task luminance to the luminance of large surfaces further awayshould not exceed 10:1.

Where luminance contrasts are not suffi-ciently marked, a monotonous impressionis created. This is also found disagreeable.

On the roads, good even local luminancedistribution is an important safety require-

ment. It permits timely identification of ob-stacles and hazards.

Harmonious distribution of brightness, e.g.in offices, can be achieved by lightinggeared to the colours and surface finishesof office furnishings. Factors which helpcreate a balanced distribution of luminancein the field of vision include:

> room-related or task area lighting

> use of lighting with an indirect compo-nent for better uniformity.

> a ratio of minimum to mean illuminance(Emin / E

_) of at least 0.7

> adequately high wall, floor and ceiling reflectance.


22

Harmonious distribution of brightnessLuminance is a measure of the brightness of a luminous or illuminated surface perceived by the human eye.

575655

52 53 54

[52– 54] Indoors, harmonious distribution ofbrightness is important for visual comfort.

[55– 57] On roads, safety is improved by goodlongitudinal uniformity – which corresponds toharmonious brightness distribution.

[58] For harmonious brightness distribution,lighting needs to be coordinated with the coloursand finishes of the room furnishings.

[59] Illuminance in a room says nothing aboutthe harmonious distribution of brightness. Thiscan be established only by determining the lumi-nance of the surfaces (cd/m2) indicated in this il-lustration.

[60] A pedestrian precinct should also be litevenly for safety, which need not mean that itbecomes “boring”.

23

59

58

60

Light and shadow are vital to ensure thatobjects, surfaces and structures are clearlyidentifiable. A bright room with nothing butdiffuse lighting and no shadows makes amonotonous impression; the lack of orien-tation, poor definition of objects and diffi-culty in gauging distances make us feel un-comfortable.

In contrast, point-like light sources with ex-tremely directional beams produce deepshadows with hard edges. Within thesecast shadows, virtually everything becomesunrecognizable; even potentially dangerousoptical illusions can occur, e.g. where toolsare used, machines are operated or stairsneed to be negotiated.

Direction of light and modelling also helpdefine visual ambience. A good ratio of dif-fuse light (e.g. from indirect lighting compo-nents) to directional light (e.g. from directlouver luminaires or downlights) makes foragreeable modelling.

Direction of light is generally defined bydaylight entering the room through a win-dow from a particular direction. Excessivelydeep shadowing, e.g. in front of a writinghand, can be offset by artificial lighting.

In offices where desk arrangements aregeared to incident daylight, it is advisable tocontrol daylight incidence by means of win-dow blinds and to use continuous rows ofluminaires on separate switching circuits tolighten disturbing shadows.

Where luminaires are arranged parallel tothe window wall, the rear row of luminairescan lighten any dark shadows that mightoccur during the day. As daylight fades, thefront row of luminaires near the windowscan be partially or fully activated to makeup for the loss of natural light.

For certain visual tasks, e.g. for appraisingsurface characteristics, marked modellingby directional light is required.

In fast ball games such as tennis or squash,adequate modelling is necessary for rapididentification of the ball, its flight path andthe place where it will land.


24

Direction of light and modellingWithout light we cannot make out objects, without shadow we see objects only as two-dimensional images. It takes directional lighting and modelling to permit 3D projection, to give objects depth.

61 62

25

[61+62] Most people prefer light to fall pre-dominantly from above and the left, since thisprevents disturbing shadows being cast on written work.

[63] To avoid harsh shadows, floodlights arearranged so that each individual beam elimi-nates the shadow created by others.

[64] Light and shadow bring out the details ofthis white marble statue.

[65+66] Only under directional light from theside can the three-dimensional structure of thewall surface be perceived; in diffuse light it appears smooth.

64

63

65 66

The light colour of a lamp is expressed interms of colour temperature Tc measured indegrees Kelvin (K). The Kelvin temperaturescale begins at absolute zero (0 Kelvin �–273° C).

Colour temperature is used to denote thecolour of a light source by comparison withthe colour of a standardized “black bodyradiator”. A black body radiator is an “ide-alised” solid body, e.g. made of platinum,which absorbs all the light that hits it andthus has a reflective radiance of zero.

When a black body is slowly heated, itpasses through graduations of colour fromdark red, red, orange, yellow, white to lightblue. The higher the temperature, the whiterthe colour. The temperature in K at which ablack body radiator is the same colour asthe light source being measured is knownas the correlated colour temperature of thatlight source.

An incandescent lamp with its warm whitelight, for example, has a correlated colourtemperature of 2,800 K, a neutral white flu-orescent lamp 4,000 K and a daylight fluo-rescent lamp 6,000 K.

For reasons of standardization, the lightcolours of lamps are divided into threegroups: dw – daylight white, nw – neutralwhite and ww – warm white.

Light colour of lamps:

Light colour Colour temperaturein Kelvin

warm white < 3,300neutral white 3,300 – 5,300daylight white > 5,300

Lamps with the same light colour can emitlight of completely different spectral com-position and thus with quite different colourrendering properties. It is not possible todraw conclusions about colour renderingfrom light colour.


26

Light colourWe experience our surroundings not just as brightness and darkness, light and shadow, but also in colour.

Numeral Ra range Light colour Colourtemperature

1st numeral 2nd + 3rd numeral in Kelvin

9 90 – 100 27 2,700 K

8 80 – 89 30 3,000 K

7 70 – 79 40 4,000 K

6 60 – 69 50 5,000 K

5 50 – 59 60 6,000 K

4 40 – 49 65 6,500 K

The international colour designation code for lamps consists of three numerals. Thefirst numeral indicates colour rendering (Ra range), the second and third colour tem-perature (in Kelvin).

67

27

[67] The way we see colours depends onmore than just the light colour and colour ren-dering properties of the lamp. Where light colourdiffers from daylight, stored “visual experience”enables us to correct colours automatically upto a point.

[68] The International Commission on Illumina-tion CIE has devised a triangle in which thecolours of light sources and body colours canbe classified. Depending on brightness, achro-matic light (i.e. white, grey or black) is found at x = y = 0.333.

All the other colours are located around thispoint. Along the straight line from the achro-matic position to the limiting curve (which repre-sents the spectral colours of sunlight) lie thecolours of the same hue but differing degrees of saturation. Saturation increases towards thelimiting curve.

The colour triangle contains all real colours. Thecurve describes the colours of the “black bodyradiator” for the given temperatures (in Kelvin).

[69– 71] Fluorescent lamps have a line orband spectrum. The examples here show thespectra of fluorescent lamps in each of the three groups dw, nw and ww.

[72] In contrast, the incandescent lamp at thebottom exhibits a continuous spectrum.71

69 70

72

68

400 500 600 700 nm

400 500 600 700 nm

400 500 600 700 nm

400 500 600 700 nm

Guaranteeing correct colour perceptionunder artificial light forms a very importantpart of the lighting designer‘s brief. The ap-pearance of coloured objects is affected bythe interaction between the colour – i.e. thespectral reflectance – of the objects we seeand the spectral composition of the light il-luminating them.

In everyday life, we come across surfacecolours which can differ in appearance de-pending on how they are illuminated butwhich we recognize for what they arethanks to stored visual experience inde-pendent of lighting.

For example, we have a stored impressionof the colour of human skin in daylight.Where artificial lighting lacks a particularspectral colour or exaggerates certaincolours in its spectrum (as is the case withincandescent lamps), skin seen under itmay appear a different colour but will stilllook “natural” because of empirical com-pensation. For coloured materials for whichno “empirical standards” exist, however,colour perception can vary widely.

The effect a light source has on the appear-ance of coloured objects is described by itscolour rendering properties. These aregrouped into grades based on the “generalcolour rendering index” Ra. The colour ren-dering index indicates how closely thecolour of an object matches its appearanceunder the relevant light source.

To determine the Ra values of light sources,eight defined test colours commonly foundin the environment are each illuminatedunder the reference light source (Ra = 100)and then under the source being evaluated.The greater the difference in the appear-ance of the test colours rendered, thepoorer the colour rendering properties ofthe light source under examination.

Under a light source with an Ra = 100 rat-ing, all the colours have the same – optimal– appearance as under the reference lightsource. The lower the Ra index, the poorerthe rendering of the surface colours of theilluminated objects.


28

Colour renderingLight and colour define the atmosphere of a room and influence our mood and sense of wellbeingby their “warmth” or “coldness”.

29

[73] Electric lamps are classed according tolight colour (dw, nw or ww) and colour renderingindex Ra (from 20 to 100).

[74] Despite identical light colour, different colour rendering properties lead to variations incolour perception. For instance, where thespectrum of a lamp contains little red light(right), red surface colours are only incompletelyrendered.

74

73

1 De luxe fluorescent lamps, daylight2 Metal halide lamps3 De luxe fluorescent lamps, white4 De luxe fluorescent lamps, warm tone5 Halogen lamps6 Incandescent lamps7 Three-band fluorescent lamps, daylight8 Metal halide lamps9 Three-band fluorescent lamps, white

10 Compact fluorescent lamps, white11 Metal halide lamps12 Three-band fluorescent lamps, warm

tone13 Compact fluorescent lamps, warm tone14 High-pressure sodium vapour lamps

(Ra � 80)15 Metal halide lamps16 Fluorescent lamps, universal white 25

17 Standard fluorescent lamps, white18 Metal halide lamps19 High-pressure sodium vapour lamps

(Ra � 60)20 High-pressure mercury vapour lamps 21 Standard fluorescent lamps, warm tone22 High-pressure sodium vapour lamps

(Ra � 20

Celsius

6,000° C

5,000° C

4,000° C

3,000° C

2,000° C

1,000° C

0° C

-273° C

Kelvin

5,300 K

3,300 K

1,000 K

0 K

Correlated colour temperature TF

dw daylight white

nw neutral white

ww warm white

100 90 80 70 60 40 20

Colour rendering index Ra

1 7

2

3

45

6 1415

16 17

18

19 2122

2091011

1313

8


30

Light generation by thermal radiators,discharge lamps and LEDsIn general, lamps generate light either by thermal radiation or by gas discharge, the radiation of which is eitherdirectly visible or is made visible by luminescent material.

Incandescent lamps

The incandescent lamp is a thermal radiatorwhich generates light by resistance heating.It consists of a tungsten filament in a glassbulb which, depending on the model, is either evacuated or filled with nitrogen orinert gas (argon).

The inert gas raises the temperature of thetungsten filament and reduces volatilization.This increases the luminous efficacy and,by hindering the blackening of the inside ofthe glass bulb, counteracts the decline inluminous flux. The luminous efficacy can befurther improved by doubling the coiling ofthe resistance wire.

However, the luminous efficacy of incan-descent lamps is basically poor. Halogenlamps generate light more efficiently; thebest luminous efficacy ratings are achievedby discharge lamps.

The mean service life of an incandescentlamp is defined as the length of service of50 % of all lamps under normal workingconditions. For general-service tungsten filament lamps this is 1,000 h. The servicelife and the luminous flux of an incandes-cent lamp are influenced by the level of thesupply voltage.

Halogen lamps

A further development of the incandescentbulb is the halogen lamp, in which the bulbis filled with halogen gas. This ensures thatvolatizing tungsten atoms are re-depositedon the coil after a “circulating process” andthereby prevents blackening of the bulb.

The main advantages of halogen lamps areincreased luminous efficacy up to around25 lm/W, a longer service life, e.g. 2,000hours, constant luminous flux, white lightcolour and small dimensions.

A distinction is made between the halogenbulbs in high-voltage lamps for 230 V oper-ation and those for low-voltage operationon 6, 12 or 24 V.

Halogen reflector lamps with a metal orspecular glass reflector deliver focusedbeams of light with various beam spreads.

In cool-beam reflector lamps 2⁄3 of the heat(IR radiation) is diverted backwards throughthe infrared-permeable specular surfaceand thereby removed from the light beam.Museum exhibits, for example, are thusprotected from excessive heat.

All thermal radiators can be dimmed with-out problems. However, low-voltage lampsrequire a special dimmer, which needs tobe compatible with the transformer.

Discharge lamps

Discharge lamps generate light by electricdischarge through ionized gas or metalvapour. Depending on the type of gas in thedischarge tube, visible light is either emitteddirectly or UV radiation is converted intovisible light by luminescent materials on theinside of the tube.

A distinction is made between low- andhigh-pressure lamps, depending on the operating pressure in the tube.

To operate, discharge lamps require a ballast, which serves mainly to limit theamount of current flowing through thelamp. To ignite a discharge lamp, a starteror igniter is required. This supplies voltageand energy pulses high enough to ionizethe gas column (discharge path) andthereby ignite the lamp.

The service life of discharge lamps is gener-ally referred to as the economic life. Thistakes account of the lamps in a lightingsystem which are rendered defective e.g.by a broken filament as well as the de-crease in luminous flux due to fatigue in thefluorescent material and deterioration of the discharge mechanism. The system lu-minous flux thus defined must not fall belowa certain minimum (80 % of output on in-stallation).

Electronic ballasts

Where electronic ballasts (EBs) are used,luminous efficacy and lamp life are in-creased. Lamps also start instantly andwithout flickering and provide constant,steady lighting with no stroboscopic ef-fects. Defective lamps are automaticallyshut down.

Fluorescent lamps

Three-band fluorescent lamps are low-pressure discharge lamps. They have threeor five particularly prominent spectral areasin the blue, green and red sectors, whichmake for good colour rendering properties.

The luminescent coating on the inside ofthe lamp tube converts the largely invisibleUV radiation of the gas discharge into visible light. The chemical composition ofthe luminescent material determines,among other things, the light colour andcolour rendering properties of the lamp.

26 mm-diameter three-band fluorescentlamps have a high luminous efficacy ratingand a long service life. As with all othertypes of fluorescent lamp, the amount of luminous flux they emit depends on the am-bient temperature: at –20° C, for example,it falls below 20 % capacity, at +60° Cbelow 80 %.

Three-band fluorescent lamps with a 16 mm diameter and shorter tube have even higher luminous efficacy ratings. These T5fluorescent lamps can only be operated by electronic ballasts (EBS).

31

[75] In the evacuated bulbs of the earliest incandescent lamps, tungsten particles settledon the inside of the bulb and made it increas-ingly dark. Today, inert gas limits the freedom ofmovement of the tungsten molecules.

tungsten inert gas

[76] In 230 V and low-voltage halogen lamps, the circulating process makes for higherluminous efficiacy and a longer life.

tungsten halogen

[77] By deflecting heat backwards, the low-voltage halogen cool-beam reflector lamp generates 2⁄3 less beam heat than other low-voltage lamps.

1 Glass2 Cool-beam facet reflector3 High-performance burner4 Base

75 76 77

1

2

3

4

in thepast

today

Energy label

Lamps across Europe display the EU energy label, which rates them in terms ofa set of energy efficiency classes from A toG. ‘A’ indicates a particularly economicalconsumer, ‘G’ an energy waster.

Ballasts are rated on the basis of the Euro-pean Energy Efficiency Index (see page42). Class C and D ballasts – models in theleast efficient categories – have long beenprohibited. An energy classification systemis also planned for luminaires.


32

The distinctive features of high-pressuresodium vapour lamps are a particularlywarm white light with no UV content andvery high luminous efficacy. Like metalhalide lamps, they are also available in el-lipsoid, tubular and double-ended designs.The lamp types with poor colour rendering(Ra � 59) are suitable for street lighting.Types with improved colour renderingproperties (Ra � 69) are predominantlyused for industrial lighting, those with goodcolour rendering (Ra � 80) find applicationsin decorative accent lighting andsalesrooms.

Metal halide lamps and high-pressuresodium vapour lamps require igniters andballasts compatible with the individual lamptypes; most can be EB-operated. Dimmingcalls for sophisticated lighting control, es-pecially to ensure colour consistency.Today, dimmable EBs are also available forthese lamps.

LEDs

In an LED, a solid-state crystal is inducedto emit light by passing an electric currentthrough it. The type of crystals used havetwo sections or regions: a region with asurplus of electrons (n-type semiconductor)and a section with a deficit of electrons (p-type semiconductor). When a directvoltage is applied, electrons flow acrossthe junction between the two regions, gen-erating light in the process.

The light thus created has a narrow-bandemission spectrum which differs accordingto the semiconductor material used. WhiteLEDs can be created by additive colourmixing or by luminescence conversion.Their colour temperatures are between4,000 and 7,000 Kelvin and colour render-ing index Ra around 70.

Among the most important advantages ofLEDs are their small dimensions, long lifeand low failure rates. Also, they emit no IRor UV radiation.

Two type series are available: “high lumi-nous efficacy” lamps in 14 W to 35 Wpower ratings for maximum economy, and“high luminous flux” lamps in 24 W to 80 Wratings for indirect or direct lighting inrooms with high ceilings. 7 mm-diameterfluorescent lamps with 6 W to 13 W ratingsare used in display, furniture and picturelights.

Fluorescent lamps and compact fluores-cent lamps operated by appropriate EBscan be dimmer-controlled without prob-lems.

Induction lamps

Induction lamps are also low-pressure dis-charge lamps. The difference is that theyhave no electrodes. The electron flow hereis induced by a magnetic field. Because induction lamps have no components thatare subject to wear, they attain an averageservice life of 60,000 operating hours.

Induction lamps are available in circularand spherical designs.

High-pressure discharge lamps

The most important high-pressure lampsare metal halide and high-pressure sodiumvapour lamps.

Thanks to the use of halogen compoundsof various metals, metal halide lampsachieve high luminous efficacy and goodcolour rendering. The high intensity, energyefficient, long life light sources are availablein ellipsoid, tubular and double-ended de-signs in warm-white and neutral-white lightcolours. Nearly all metal halide lamps haveUV-absorbing bulbs.

78

33

[78] Fluorescent lamps work with mercuryvapour under low pressure. When current flows,electrons are emitted from both tungsten wireelectrodes. On their way through the dischargetube, they collide with the mercury atoms. In thiscollision, a mercury electron is deflected from its path and orbits at a greater distance from thenucleus. As it springs back into its original orbit,it releases the collision energy in the form of UVradiation, which is then transformed into visiblelight by the fluorescent coating on the inside ofthe discharge tube. The light colour and colourrendering of fluorescent bulbs can be variedover a wide range by the chemical compositionof the coating.

[79] As burning time increases, the luminousflux of fluorescent lamps diminishes and individ-ual lamps fail. These factors determine the sys-tem luminous flux, which must not fall below80% of the luminous flux on installation. This decline in luminous flux needs to be taken intoaccount when a lighting system is installed (see“Maintenance factor”, page 14)

[80] High-pressure discharge lamps possess a burner in which light is generated by electricaldischarge in a gas, a metal vapour or a mixtureof the two. The metal halide lamp shown abovehas a transparent ceramic burner, which en-sures uniform colour characteristics throughoutthe life of the lamp.

[81] LEDs are individual punctual light sourcesand can be white or coloured. They are onlythree to five millimetres high and thus permit totally new luminaire designs.

80 81

79


34

Lamps15

16

16

1410

9

3

2

1

13

12

11

65

Nr. Lamp type Power Luminous flux Luminous flux Light colour Colour render-rating (Watts) (lumens) (lumens/Watts) ing index

Linear three-band fluorescent lamps1 T5; 16 mm dia.1) high luminous efficacy 14 – 35 1,250 – 3,6502) 89 – 104 ww,nw,dw 80 – 892 T5; 16 mm dia.1) high luminous flux 24 – 80 1,850 – 7,0002) 77 – 88 ww,nw,dw 80 – 893 T8; 26 mm dia. 18 – 58 1,350 – 5,200 75 – 903) ww,nw,dw 80 – 89

Compact fluorescent lamps4 2-, 4-, 6-tube lamp 5 – 120 250 – 9,000 50 – 75 ww,nw 80 – 895 2-tube lamp 18 – 80 1,200 – 6,000 67 – 75 ww,nw,dw 80 – 896 4-tube lamp 18 – 36 1,100 – 2,800 61 – 78 ww,nw 80 – 89

2D-lamp 10 – 55 650 – 3,900 65 – 71 ww,nw,dw 80 – 89

Energy-saving lamps7 Incandescent shape 5 – 23 150 – 1,350 30 – 59 ww 80 – 898 Standard shape 5 – 23 240 – 1,500 48 – 65 ww 80 – 89

230 V halogen lamps9 with jacket 25 – 250 260 – 4,300 10 – 17 ww � 90

10 miniature 25 – 75 260 – 1,100 10 – 15 ww � 9011 with reflector 40 – 100 ww � 9012 with base at both ends 60 – 2,000 840 – 44,000 14 – 22 ww � 90

Low voltage 12 V halogen lamps13 with reflector 20 – 50 ww � 9014 pin-based lamps 5 – 100 60 – 2,300 12 – 23 ww � 90

Metal-halide lamps15 with base at one end 35 – 150 3,300 – 14,000 85 – 95 ww,nw 80 – 89, � 9016 with base at both ends 70 – 400 6,500 – 36,000 77 – 92 ww,nw 80 – 89, � 90

High-pressure sodium vapour lamps17 tubular 35 – 1,000 1,800 – 130,000 51 – 130 ww 20 – 39

Low-pressure sodium vapour lamps18 tubular 18 – 180 1,800 – 32,000 100 – 178 yellow

Light emitting diodes19 LED 0.7 – 1.5 18 – 27 13 – 23

Light colour: ww = warm white, nw = neutral white, dw = daylight white 1) for EB operation only 2) luminous flux at 35° C 3) luminous efficacy increases to

Good lighting depends on the right choice oflamp. Below are the most important lamptypes and their specifications.

Three-band fluorescent lamps (1, 2, 3)Three-band fluorescent lamps offer high lumi-nous efficacy coupled with good colour ren-dering and a long service life. Operated byelectronic ballasts (EBs), they achieve aneven higher luminous efficacy and longerservice life. 16 mm-diameter T5 lamps aredesigned for EB operation only. With appro-priate EBs, all three-band fluorescent lumi-naires can be dimmer-controlled.

Compact fluorescent lamps (4, 5, 6)Compact fluorescent lamps have the samecharacteristics as three-band fluorescentlamps. Here too, luminous efficacy, service lifeand lighting comfort are enhanced by elec-tronic ballasts and dimmer control is possiblewith appropriate EBs.

Energy-saving lamps (7, 8)Energy-saving lamps have a built-in ballastand a screw base (E14 or E27). They con-sume as much as 80 % less power and havea considerably longer life than incandescentlamps.

230 V halogen lamps (9, 10, 11, 12)Halogen lamps for line operation produce anagreeable white light with good colour render-ing properties. They have a longer service life

than incandescent lamps and achieve higherluminous efficacy. They are fully dimmableand available also as reflector lamps.

Low-voltage 12 V halogen lamps (13, 14)Low-voltage halogen lamps produce anagreeable white light with very good colourrendering properties. To operate them, atransformer is needed to reduce the voltageto 12 V. With appropriate transformers, theycan be dimmer-controlled. IRC (Infra-RedCoating) lamps consume 30 % less power forthe same luminous flux.

Metal halide lamps (15, 16)These lamps are noted for their high luminousefficacy and excellent colour rendering prop-erties. Modern metal halide lamps have a ce-ramic burner, which produces light of a con-stant colour throughout the lamps‘ life. Aballast is needed to operate metal halidelamps. EB operation makes for a longer lamplife and enhanced lighting comfort.

High-pressure sodium vapour lamps (17)Very high luminous efficacy and long lamp lifemake high-pressure sodium vapour lamps ahighly economical option for outdoor lighting.They consume only half as much power ashigh-pressure mercury vapour lamps. Appro-priate ballasts and igniters are needed to op-erate high-pressure sodium vapour lamps.

Low-pressure sodium vapour lamps (18)This type of lamp is noted for having a higherluminous efficacy than any other. Because ofits monochromatic beam, it is particularlygood at penetrating fog and mist. Low-pres-sure sodium vapour lamps are used for illumi-nating port and lock control installations andfor security lighting.

Light-emitting diodes (19)LEDs come in numerous shapes and colours.They are extremely small, have a high resist-ance to impact and a very long service lifeand emit neither IR nor UV radiation. Given aspecial fluorescent coating, LEDs producewhite light. LEDs are designed for d.c. opera-tion.

35

17 18

19

8

7

Base

G5G5G13

G23, G24, GX24, 2G7/82G112G10

GR8, GR10, GRY10

E14, E27E14, E27

E14, E27G9

E14, E27, GZ10, GU10R7s

GU5,3G4, GY6,35

G12, G8,5RX7s, Fc2

E27, E40

BY22d

81 – 100 lm/W with EB operation

Selection of luminaires

Luminaires are selected on the basis of:> application interior or exterior luminaire, > type and number of lamps incandescent lamp, low-pressure or high-pressure discharge lamp,> structural type open or closed luminaire,> type of mountingrecessed, surface-mounted or pendant luminaire,> lighting characteristicssuch as luminous flux distribution, luminousintensity distribution, luminance distributionand light output ratio,> electrical characteristics, including com-ponents required for lamp operationelectrical reliability, protection class, radiointerference suppression, ballast,igniter/starter, etc.,> mechanical characteristicsmechanical reliability, degree of protection,fire safety features, impact resistance, ma-terial properties, etc., > size, construction and design.

Luminous flux distribution

Total luminous flux �L is the sum of the partial luminous flux emitted in the lowerhalf �U and upper half �O of the luminaire.Luminaires are categorized by the amountof lower luminous flux they emit and as-signed to groups A to E as defined in DIN5040.

For most outdoor applications, luminairesfor direct lighting are normally the preferredoption. However, for decorative lighting inpedestrian precincts, parks etc., luminaireswith a small indirect lighting component canbe usefully employed to highlight trees orbuilding façades.

Luminous intensity distribution

The three-dimensional distribution of the lu-minous intensity of a luminaire is indicatedby the luminous intensity distribution model.It can be shown for various planes in polardiagrams (IDCs). To facilitate comparison,the intensities relate to 1,000 lm of thelamps in the luminaire and are expressed


36

LuminairesGeneral requirements and lighting characteristics

82

37

accordingly as cd/klm (candelas per kilo-lumen).

The shape of an IDC shows whether the luminaire has a narrow- or wide-angle,symmetrical or asymmetrical beam.

Intensity distribution curves are usually established under standardized luminaireoperating conditions using a computer-controlled rotating mirror goniophotometer.They provide the basis for planning interiorand exterior lighting.

Luminance distribution and shielding

To assess the glare produced by interior luminaires, it is necessary to know theirmean luminance at angles critical for glare.Mean luminance is the quotient of luminousintensity and the effective luminous areaperceived by observers.

In street lighting, glare depends, amongother things, on the size of the luminousarea and the light emitted by the luminaires.Luminous intensity at critical beam angles is limited by deflection within the opticalcontrol system.

85

[82+83] CAD systems are used for luminairedevelopment.

[84] Computer-generated three-dimensionalintensity distribution of an exterior luminaire.

83 84

[85] Computer-calculated reflector/louvercombinations are used to achieve optimal luminance distribution with effective luminaireshielding.

In order to direct, distribute or filter the lu-minous flux of lamps, two basic kinds of“lighting materials” are used:

> reflective materials> translucent light-transmitting materials.

Reflective materials are used to reflect asmuch light as possible. They can be subdi-vided into materials for:


38

> directional reflection

e.g. specular reflectors and louvers ofhighly polished anodised aluminium; cou-pled with precise specular design, theseoptical controllers make for finely definedbeams and luminance control.

> mixed reflection

e.g. satinised specular louvers; in contrastto matt materials, the surface of these opti-cal controllers has a more pronounced di-rectional component for “defined” shieldingconditions.

This is an important quantity for assessingthe energy efficiency of a luminaire and itslighting performance.

Light output ratio �LB is the ratio of the lu-minous flux radiated by a luminaire to thesum of the luminous fluxes of its lamps,measured under specific operating condi-tions.

Those conditions define the normal operat-ing position of the luminaire and a normalambient temperature of 25° C.

Although a track-mounted general-diffuseluminaire has a higher light output ratio �LB

than a shielded specular luminaire, it alsocauses more glare. Specular louver lumi-naires, for instance, produce substantially

Lighting materials

Light output ratio �LB

86 87 88

> diffuse reflection

e.g. matt specular louvers or reflectors andlouvers with enamelled surfaces; the lumi-naire face is clearly visible owing to itshigher luminance.

39

(such as glass and plastics) are alsoemployed for optical control by harnessingtheir capacities for refracting and reflectinglight.

higher illuminance on the working plane.Light output ratio is thus not a reliableyardstick for illuminance on the workingplane.

Directionally translucent materials

When a beam of light passes from oneoptical medium into another, it changesdirection according to the angle of inci-dence and thus undergoes optical control.

89 90

Planning at 25° C

Light output ratios are measured in the laboratory at an

ambient temperature of exactly 25° C. Hence the need to

plan a lighting installation on the basis of the luminous flux

established for a lamp at 25° C. Otherwise, the illuminance

values computed for the installation will be wrong.

Class of protection

Luminaires are divided into three classes ofprotection according to the protectivemeasures taken against electric shock:

> Class I: Touch-accessible metal components areconnected to the protective conductor. Theprotective conductor terminal is indicatedby the symbol

> Class II: Live components are provided with addi-tional protective insulation. Connection tothe protective conductor is not allowed.Symbol:

> Class III: Luminaires are operated on protectiveextra-low voltages (< 42 V) that present nodanger to human beings. Symbol:

Degrees of protection IP

The mechanical design of luminaires mustbe such that they are adequately protectedagainst the ingress of foreign bodies andmoisture. The degree of protection is indi-cated by the IP (Ingress Protection) num-bering system.

The first numeral indicates the degree ofprotection against foreign bodies, the sec-ond numeral protection against water (seetable and figs. 93 – 98 on page 41)

An IP 20 luminaire, for example, is pro-tected against the ingress of foreign bodies� 12 mm but not against moisture. A lumi-naire designed for use in damp interiors,with a degree of protection of IP 65, is pro-tected against the ingress of dust andagainst jets of water.

Electromagnetic compatibility

Electrical equipment and electronic circuitscan send out intended or unintended highfrequency electromagnetic signals, whichare either beamed through the air or fedinto cables. Such equipment is also sus-ceptible to external interference which canprevent it from operating normally. Growinguse of electronic equipment makes it vitalto ensure that this kind of cross-interfer-ence is suppressed. Luminaires for dis-charge lamps are potential sources of suchinterference.

Under Ordinance 242/1991 issued by theFederal Minister for Post and Telecommuni-cations on 11 December 1991, luminaireslicensed for use in Germany are required tomeet certain standards of immunity to inter-ference and interference suppression. Theordinance is based on the ElectromagneticCompatibility Act, which incorporates ECDirective 89/336/EEC “ElectromagneticCompatibility” into German law.

Compliance with the relevant standards isevidenced by the EMZ symbol of the VDEtest and certification institute.


40

LuminairesElectrical characteristics, ballasts

41

[91] Luminaires are exposed to a range of ex-ternal influences.

[92] Luminaires need to be designed for con-formity with one of the three electrical classes ofprotection against electric shock.

[93– 98] The luminaires are examples of differ-ent IP degrees of protection and show that thehigher degrees of protection require much moresophisticated mechanical solutions.

92

93

91

Degree of 1st numeral 2nd numeralprotection foreign body protection water protection

IP 11 foreign bodies > 50 mm drops of water

IP 20 foreign bodies > 12 mm unprotected

IP 23 foreign bodies > 12 mm spraywater

IP 33 foreign bodies > 2,5 mm spraywater

IP 40 foreign bodies > 1 mm unprotected

IP 44 foreign bodies > 1 mm splashwater

IP 50 dust-protected unprotected

IP 54 dust-protected splashwater

IP 65 dustproof jetwater

IP 66 dustproof floodwater

IP 20 IP 20

IP 40 IP 54

IP 54 IP 65

LN

PE

94

95 96

97 98

Fire safety

When selecting luminaires, considerationshould be given to the fire-resistance of themounting surfaces and the luminaire sur-roundings.

DIN VDE 0100 Part 559 stipulates that lu-minaires with the symbol -are suitable fordirect installation on building materials thatremain dimensionally stable and stationaryat temperatures up to 180° C. Luminaireswithout a fire protection symbol may onlybe directly installed on non-flammablebuilding materials such as concrete.

At locations exposed to fire hazards, how-ever, where highly flammable materials suchas textile fibres etc. may be deposited onluminaires, only models with the -symbolmay be installed. Such luminaires are de-signed so the temperature of their surfacesdoes not rise above the stipulated thresholdtemperature. Luminaires for direct mountingin or on furnishings, e.g. furniture, mustbear the or symbol, depending onthe material of the mounting surface.

Impact resistance

Luminaires for use in sports facilities inwhich ball games are played must be im-pact resistant and be marked with the sym-bol indicating suitability for sports facilityuse. This also applies to luminaire acces-sories and mounting components

Energy efficiency of luminaires

Most of the electrical energy consumed isconsumed by the lamp and its operatinggear. To indicate the energy consumption of the ballast/lamp system, an energy clas-sification system has been introduced atEuropean level (Directive 2000/55/EC onenergy efficiency requirements for ballastsfor fluorescent lamps).

As in the case of lamps and ballasts (seepage 32), a separate energy classificationsystem is also planned for luminaires.

Ballasts

The EEI (Energy Efficiency Index) distin-guishes between seven classes of ballast:

A1 Dimmable electronic ballasts (EBs)A2 Electronic ballasts (EBs) with re-

duced lossesA3 Electronic ballasts (EBs) B1 Magnetic ballasts with very low

losses (LLBs)B2 Magnetic ballasts with low losses

(LLBs)C Magnetic ballasts with moderate

losses (CBs)D Magnetic ballasts with very high

losses (CBs).

The sale of Class D ballasts has been pro-hibited since 21 May 2002; Class C ballastshad to be withdrawn from the market by 21 November 2005.

One thing all discharge lamps have in common is their negative current/voltagecharacteristic: a current supplied at con-stant voltage reaches an intensity thatwould destroy the lamp. Hence the needfor discharge lamps to be operated by ballasts. These serve to limit the currentand, in combination with e.g. starters, to ignite the lamps

Growing energy awareness has promptedmajor technological improvements in ballasts for fluorescent lamps. The conven-tional ballast (CB) has now been super-seded by the (inductive) low-loss ballast(LLB) and the electronic ballast (EB).

Electronic ballasts convert 230 V/50 Hz linevoltage into a high-frequency a.c. voltage of 25 to 40 kHz, which lowers the power intake of a 58 W lamp to around 50 W whilemaintaining virtually identical luminous flux.The power required by a lamp/EB system in our example is reduced to 55 W, whichrepresents a 23% saving in comparisonwith the CB system. Use of efficient, en-ergy-saving ballasts is encouraged bymeasures taken by the EU. Today, morethan 40% of new and refurbished lightingsystems with fluorescent – including com-pact fluorescent – lamps are already fittedwith EBs.

In addition to the considerable energy savings achieved, making for short EB payback times of only a few years, high fre-quency EB operation of fluorescent lampsand a growing number of other dischargelamps has other advantages:

Advantages of electronic ballasts (EBs)

> low ballast losses > higher lamp luminous efficacy> optimal transformation of wattage

into light > enhanced lighting comfort and light-

ing quality> reduced operating costs > no flicker due to higher operating

frequency> flicker-free shutdown (filament pre-

heating for instant start up) > lower operating costs> reduced air-conditioning costs > no starter, no p.f. correction capacitor > can be run on a.c. or d.c. current > constant lamp performance over

wide voltage range > suitable for emergency lighting > low magnetic induction interference > use in medical examination rooms > defective lamps automatically shut

down (fire protection) > approx. 50 % longer lamp life > dimmer control possible


42

Luminaire fire protection symbols

Luminaires for mounting on building parts non-flammable up to180° C.

As F symbol, but suitable for use with thermal insulation backing.

Luminaires for mounting in/on furniture where the mounting surface is non flammable up to 180° C.

Luminaires for mounting in/on furniture where the mounting surface is non flammable up to 95° C in normal operation.

Luminaires for locations exposed to fire hazards. Temperature ofhorizontal luminaire surfaces max. 90° C in normal operation.Glass surfaces of fluorescent lamps max. 150° C.

Other symbols on luminaires

Impact-resistant to VDE, “Not for tennis” if openings > 60mm

Protected against explosion

Max. permissible ambient temperature, deviating from 25° C ta…° C

Non-permissible lamps

Min. clearance from illuminated surface

43

COOLBEAM

99

Transformers

Operating low-voltage halogen lamps re-quires transformers with an output voltageof 6 V, 12 V or 24 V.

A distinction is made between conventionaland annular core transformers; the differ-ence is less a matter of power dissipationthan of size.

Additional features provided by electronictransformers include automatic shutdown in open circuit, ability to withstand short circuits, and gentle starting for longer lamplife.

Advantages of electronic transformers

> compact size> low weight> low power dissipation > low internal resistance > no noise generation > high efficiency> overload and overheating prevented

by power control without lamp de-activation

> non-encapsulated, therefore re-pairable if defective

> soft starting - no current peaks onactivation

> electronic protection against short-circuiting

P.f. correction capacitors

P.f. correction capacitors serve to improvethe power factor. They reduce the inductivereactive power of the ballasts (chokes) thatcontributes to the load on the electricalequipment, e.g. leads, cables, transformersand switches. Power utilities stipulate thatp.f. correction capacitors need to be usedin luminaires with discharge lamps.

P.f. correction capacitors must bear thesymbol F (flameproof) or FP (flame- and explosion-proof), display a test symbol froma recognised testing agency and beequipped with a discharge resistor.

P.f. correction capacitors are not requiredwhere EBs are used.

Starters and igniters

Starters for fluorescent lamps operated bymagnetic ballasts complete or open thepreheating current circuit of a fluorescentlamp and thereby initiate the ignitionprocess. A distinction is made between uni-versal and fused rapid starters.

Starters are not required where EBs areused.

Metal halide lamps and high-pressuresodium vapour lamps need a starting volt-age pulse of the order of 1 to 5 kV. Igniterswith special electronic switches are thusused to ignite high-pressure dischargelamps.

For the immediate hot re-ignition of extin-guished metal halide or high-pressuresodium vapour lamps, igniters with voltagesconsiderably higher than 5 kV are required.


44

LuminairesOperating devices, regulation, control, BUS systems

[100] Operating gear is essential - both for fluorescent lamps for general lighting and forhalogen lamps for accent lighting.

45

[101] Transformers for low-voltage lamps turnthe 230 V supply voltage into a lamp operatingvoltage of 6, 12 or 24 V. On the secondary sideare correspondingly high currents requiring asignificant increase in the cross-section of thetransformer winding and of the lamp connectioncable.

[102] To compensate the inductive reactivepower of conventional ballasts (CBs) and low-loss ballasts (LLBs), luminaires with fluorescentlamps are fitted with a capacitor parallel to theline connection (230 V).

[103] Electronic ballasts (EBs) require neitherstarters nor p.f. correction capacitors.

101

100

102

103

Low-voltage installation

Because of their low operating voltages,low-voltage installations constitute no im-mediate hazard to human beings. It needsto be borne in mind, however, that thestepped-down voltage gives rise to veryhigh currents.

Examples: 230 V 100 W lamp:current I = 0.43 A12 V 100 W lamp:current I = 8.33 A).

If cables, contacts, terminals or switchesare not adequately dimensioned, these highcurrents can cause overload. To avoid firehazards in such cases, special installationrequirements need to be observed.

Low-voltage plug-in systems, with plugs,couplings and cables, are a proven profes-sional solution.

Regulation and control

Lighting regulation and control play a central role in modern building service man-agement. As well as the energy savingsthey permit, they are increasingly appreci-ated for the convenience they provide andthe motivational boost delivered by dynamiclighting.

Lighting can be adjusted according to theamount of natural light available or the posi-tion of the sun (daylight control or regula-tion), according to whether the room is inuse (presence control) or according to thelighting atmosphere required (e.g. RGBcontrol).

Daylight-dependent regulation

Harnessing the daylight that enters a roomthrough skylights or windows and combin-ing it with artificial lighting saves a greatdeal of energy. The artificial lighting is thenactivated or slowly and steadily intensifiedwhen the daylight alone is not sufficient.

As a lighting management solution, this isgenerally realised by installing a daylight dependent regulation system that delivers aconstant lighting level by adding regulatedartificial lighting to available daylight. Soeven if the amount of available daylightchanges, the illuminance required on theworking plane is kept virtually the same byhigher or lower levels of artificial lighting.

This means that when the light outside isbright, the artificial lighting is lowered, andwhen there is less daylight available – atdawn, dusk or in winter – its level is raisedaccordingly.

Daylight-dependent lighting regulation is realised by dimming and/or partial switch-ing in response to > light sensors at individual workplace luminaires> light sensors in the room> exterior light sensors

DALI – digital lighting management

DALI (Digital Addressable Lighting Interface)is an intelligent lighting management sys-tem specifically developed to meet the re-quirements of modern lighting technology:easy to use and cost-efficient, it is also designed for use with interface modulespermitting integration in building manage-ment systems with EIB (European Installa-tion Bus) or LON (Local Operating Network)circuitry.

DALI controls lighting through all DALI com-ponents and can address each applianceindividually. It can assign each EB (= lumi-naire) equally, for example, to as many as16 groups, define 16 lighting production attributes for each individual fitting or dimall EBs together in one synchronized opera-tion.

The members of AG-DALI, the DALI work-ing group in the German electrical and electronic manufacturers‘ association ZVEI,include leading European and US manufac-turers of electronic ballasts and lightingcontrol and regulation systems.

Central management of building installations – Bus systems

The increasing complexity of building tech-nology and the control and monitoring of allbuilding installation and service systems,e.g. heating, air-conditioning, alarm and se-curity systems, lighting, window blind con-trol etc., require a new approach to buildingmanagement that incorporates all the indi-vidual systems – including lighting – in anintelligent control system.

Microelectronics and data transmissiontechniques make it possible for all the nec-essary system groups to “communicate”with each other via a shared bus network.

Information from sensors (e.g. photoelectricbarriers, infrared receivers, wind gauges,brightness sensors) is conveyed by the busnetwork. The appropriate assignment ofsensors (receivers) and actuators (switches)permits a wide variety of functions to beprogrammed for control and regulation.


46

47

[104] Dimming thermal radiators: correlation ofwattage and luminous flux.

[105] Dependence of system power and luminous flux in dimmed fluorescent lamps, here16 mm diameter lamps

[106] Bus systems combine the advantagesof greater lighting comfort, simple networking oftrades and energy savings. All electrical con-sumers are supplied with voltage. The controlsignals are transmitted via a bus line: sun andwind sensors, switches and infrared transmittersdeliver input signals that are converted and sentto the controlled luminaires and blinds.

[107] Daylight-dependent regulation as thesum of available daylight and regulated artificiallight for a constant lighting level on the workingplane.

heavy current line

bus

107

104 105

106

A wide variety of luminaires are available to cater to the diverse technical and design requirements of the broad range of lighting applications. The examples shown on these two pages are only asmall selection. In particular, they do not include luminaires designedfor special applications, such as tunnel luminaires, building securityluminaires, luminaires for explosive atmospheres, air-conditioning luminaires and clean room luminaires. More information about luminaire systems and manufacturers is available on the internet atwww.all-about-light.org.


48

Luminaires

Recessed louver luminaires

Surface-mounted louver luminaires Direct/indirect pendant luminairewith optical control panels

Recessed wallwasherswith asymmetrical beam

Spots on power track (left)and swivellable recessed downlights (right)

Medical supply unit, horizontalwith direct/indirect beam

Floodlightswith asymmetrical beam

108

110 111 112 113

117116115114

118 119 120 121

109

49

Direct/indirect recessed luminaires Downlights with symmetrical beam (left)and asymmetrical beam (right)

Direct/indirect stand-alone office luminaire with desktop luminaire

Wall luminaires as surface-mounted luminaire (left) and as recessed luminaire (right)

Escape sign luminaire for identifying escape route

Direct/indirect stand-alone domestic luminairewith tabletop luminaire

Bollard luminaire (left)Recessed ground luminaire ((right)

Post-top luminaire (left) Light stele (right)

122

126 127

123 124 125

129

130 131 132 133

137136135134

128

Interior lighting

Interior lighting systems need to conform tothe relevant standards.

The following are required to plan a lightinginstallation:

> groundplan and sectional views of therooms, with room dimensions> positions of room openings such asdoors and windows> details of ceiling construction> colours and reflectance of ceiling, walls,floor and furnishings> purpose of the room, proposed visualtasks> location of work zones> arrangement of furniture and/or machinery> operating conditions, e.g. temperature,humidity, exposure to dust

Appropriate light sources and luminairesshould be selected on the basis of thesedata. After the number of lamps has beencalculated for the illuminance required, thenumber and arrangement of luminaires canbe determined. Lighting, mounting andmaintenance factors, and architectural considerations all play an important role inthe planning process.

The architect‘s preferences for certaintypes of luminaire and luminaire arrange-ments need to be balanced against efficientand ergonomically correct use of lightingtechnology.

As well as the technical aspects of lighting,the economy of a system must also betaken into account.

Lighting planning by the lumen method

This method is described in “Projektierungvon Beleuchtungsanlagen nach demWirkungsgradverfahren” (Planning lightingsystems by the lumen method). Publishedby the Deutsche Lichttechnische Gesell-schaft eV (LiTG), it also includes utilance tables for a number of standard luminaires.

The number of luminaires required for anydesired illuminance can be calculated usingthe following formula:

n = E � Az � � � �B � WF

Key

n number of luminairesE illuminance requiredA area or partial area of roomz number of lamps per luminaire� luminous flux of a lamp�LB light output ratio�R utilance �B �LB � �R coefficient of utilizationWF maintenance factor

Utilance is a function of the luminous fluxdistributed by the luminaire, the geometryof the room and the reflectance of roomsurfaces.

The coefficient of utilization �B includes thelight output ratio �LB and the utilance �R.

Extensive tables of coefficients of utilization�B are supplied by luminaire manufacturers.

Planning lighting with computer software

The lumen method is used to calculate thenumber of luminaires required for a givenmean illuminance. The illuminance calcula-tions at different points in the room are performed by computer. Special software is available for this purpose.

Using menu-driven inputs, lighting planningsoftware provides a complete set of lightingcalculations – from initial rough outline tofully documented, comprehensive proposal.Numerous help functions are available atthe touch of a key; graphic displays facili-tate input and the interpretation of results.Computer graphics provide a realisticimage of the lighting system.

In addition to furnishing the technical docu-mentation for a lighting project, programscan also draw up a list of materials togetherwith a breakdown of the luminaires of eachtype required in the room, including a de-scriptive text.

Street lighting

The purpose of street lighting is to improveroad safety during darkness. It can only doso, however, if it meets key lighting criteria.This entails satisfying the minimum require-ments needed to enable drivers to makeout shapes and movements at a safe dis-tance and thus respond appropriately tothe presence of people and objects in thetraffic area.

The challenge for the lighting planner is tomeet the requirements laid down in roadsafety standards and regulations for lumi-nance, longitudinal and overall uniformityand glare limitation. The result should be aclear “image” of the road ahead. Capital expenditure, operating and maintenancecosts need to be low to ensure an eco-nomical lighting system. This means thatthe luminaire arrangement, the types of


50

Lighting planningLighting installations should be planned so that users are satisfied and energy is not wasted. The lighting designerneeds to take account of the requirements set out in relevant standards.

51

[138] Planning software computes the illuminance at a large number of points in theroom and produces a graphic display of the results.

[139] The computer printout shows the luminaires and the impact of the lighting on thefurnished room.

[140] The computer simulation of the illumi-nated square and adjacent street at night provides a realistic view of the installation in operation – enabling the lighting designer tocheck his or her work.

138 139

luminaires and the lamps used in themneed to be selected to produce an optimalsolution for the geometry of the road.

As for the choice of appropriate luminaires,the most economical options are luminaireswith specular optical systems for high-pressure discharge lamps.

To calculate the average roadway lumi-nance and uniformity of luminance, it isnecessary to know the luminous intensitydistribution of the luminaires, the luminousflux of the lamps, the geometry of the in-stallation and the reflective properties of theroad surfaces. The figures for the last parameter can be taken from standard roadsurface tables or obtained by measurementusing a road reflectometer.

140


52

In lighting engineering, measurements aretaken to

> check lighting proposals,> check the condition of existing lightingsystems to determine whether maintenanceor refurbishment are required,> compare different lighting systems.

Standards and regulations set out stipula-tions to ensure that measurement and eval-uation methods are standardized. Importantvariables are:

> illuminance E, e.g. as horizontal illumi-nance Eh, as vertical illuminance Ev, ascylindrical illuminance Ez or semi-cylindricalilluminance Ehz

> luminance L, e.g. in street lighting, tunnellighting or interior lighting> reflectance �, e.g. of ceilings, walls,floors, in workplace interiors and sportshalls> the reflective properties of road surfaces,e.g. in street and tunnel lighting> line voltage U and/or ambient tempera-ture ta for lighting systems with lampswhose luminous flux is dependent on theservice voltage and/or the room or ambienttemperature.

In practice, the variable measured most frequently is illuminance. For this, instru-ments with a relative spectral sensitivitycomparable to that of the human eye V(�)

are used. Oblique incident light needs to bemeasured in line with the cosine law.

When preparing photometric procedures,the following need to be established:

> geometric dimensions of the lighting system, > type of system/nature of interior and activity, > variables to be measured and location ofmeasuring points,> general condition of the system, e.g.age, date of last cleaning and last lamp replacement, degree of soiling.

Before measurements are taken, lampsshould be left on long enough for the sys-tem to reach a steady state and interfer-ence by extraneous light (e.g. daylight influencing interior or vehicle lighting, shopwindow or advertising lighting influencingoutdoor lighting) should be eliminated. Interference due to obstacles or shadowscast by persons taking measurements mustalso be avoided.

For illuminance measurements, the groundor floor area of the installation in questionshould be divided into – preferably square– patches of equal size. To avoid obtainingonly maximum values, e.g. directly underluminaires, the measurement grid thusformed should not reflect the modular dimensions of the luminaire arrangement.

Measuring lighting systemsMethods have been developed for verifying lighting installation designs but these are mostly intended for the professional user, such as the architect or lighting designer, and not for the layman.

Photometer classes in accordance with DIN 5032-6

Class Quality Application

A high precision photometry

B medium industrial photometry

C low rough photometry

53

However, symmetrical features of lightingsystem, room or outdoor space can beusefully employed to reduce the number ofmeasurements required.

Measurements are presented in tables. A graphic representation of illuminances inisolux curves is obtained by joining uppoints of equal illuminance.

To determine mean illuminance E_

, the indi-vidual measurements are added togetherand divided by the number of points atwhich measurements are taken.

The uniformity of illuminance g1 is the quotient of the lowest illuminance value as-certained Emin and the mean illuminance E

_

calculated.

Uniformity g2 is the ratio of Emin to the high-est illuminance value ascertained Emax.

A record of each measurement should bekept, documenting, for example, not justthe values themselves but also the ambientconditions, details of lamps, luminaires andthe geometry of the lighting system.

[141] Horizontal illuminances are measured onthe working plane - generally 0.75 m above thefloor - and max. 0.10 m above the ground oncommunication routes, roads or in parkingareas.

Vertical illuminances at indoor and outdoorsports facilities are measures 1.0 m above thefloor or ground.

[142] For assessing a street-lighting system,the luminance L of the road surface/roadway ismeasured with a luminance detector.

141

142

0.75 m

1.0 m

0.1 m

E

L

Illuminance E:Incident light – invisible to the eye (measured with a luxmeter)

Luminance L:reflected light – visible to the eye(measured with a luminance meter)


54

[143] Taking account of all the individual fac-tors that contribute to the total cost of a lightingsystem shows that technological improvementsin lamps and luminaires make for considerablesavings.

143

Project planning needs to include an energybalance calculation and an economic feasi-bility study.

Cost comparisons only make sense wherethe quality, service life, serviceability andmaintenance requirements of luminaires aswell as the availability of spare parts andcompliance with lighting quality features arecomparable and guaranteed.

Appropriate, precise planning, competentselection of lamps, operating devices andluminaires, and an optimal luminairearrangement are prerequisites for a lightingsystem which will save energy and reducecosts

New innovative techniques and computer-aided planning can help here. Technologicalprogress has brought numerous improve-ments in modern lamps, luminaires andlighting techniques, e.g. increased luminousefficacy in fluorescent lamps, reducedpower dissipation in ballasts, improved lightoutput ratios, increased coefficients of uti-lization due to more practical luminaire sys-tem design and more precise lighting plan-ning methods.

Lighting costsWhether new systems are being installed or old systems refurbished, energy consumption and cost are importantcriteria for lighting system planning.

55

Key:

K Total annual costsK1 Cost of one luminairek1 Service of capital for K1 (interest and

depreciation) in %K2 Costs of installation materials and

mounting per luminairek2 Service of capital for K2 (interest and

depreciation) in %R Cleaning costs per luminaire and year n1 Total number of lampsn2 Number of lamps per luminaire K3 Price of one lampK4 Cost of replacing one lampP Power consumption of one lamp incl.

ballast in kWA Cost of electricity per kWh incl. pro rata

provision costs (basic charge) tL Rated service life of lamp in h tB Annual operating hours

Capital costs

k1 k2

K = n1 �100� K1+

100� K2�

n2

Energy costs

+ n1 � tB � a � P �

Lamp replacement, system maintenance

tB R+ n1 � (K3 + K4) �tL n2

Different lighting systems can becompared by applying the costformula.

[144] Precise planning is vital to ensure thatlighting is both tailored to requirements and energy-efficient.

[145] In street lighting, a great deal of energyand expense can be saved by completely renewing lighting facilities or upgrading to modern lighting technology.

145

144


56

Technological development has focusedprimarily on such things as the fluorescentlamp and the ballast and has chiefly beengeared to boosting their luminous efficacy.The chart “Milestones to energy conserva-tion with modern lighting” shows how muchhas been achieved in reducing power requirements. The first breakthrough camewith the development of new low-loss ballasts (LLBs); then electronic ballasts(EBs) appeared on the scene. In a paralleldevelopment, the three-band fluorescentlamp made its debut in the market, joinedlater by a slimline design with a 16 mm diameter.

Luminaires

A luminaire is efficient if it has a high lightoutput ratio and if its intensity distributioncurve is tailored to the application. High-grade materials and a high standard ofworkmanship improve a luminaire‘s lightoutput ratio and, moreover, extend its use-ful life.

Efficiency potentials

Modern lighting technology offers consider-able potential for increasing efficiency andthus conserving energy. The chart “Effi-ciency potentials of modern technology”shows a comparative overview of the sav-ings that can be achieved by variousmeans. Presence control systems switchlights off when no one is in the room. Dim-ming to the maintained illuminance valueenables significant energy savings to bemade, especially with new lighting installa-tions.

The greatest economies are achieved byoptimal application of each individual measure. Where measures are combined,lighting system efficiency is enhanced evenmore.

Daylight utilisation

The greatest savings can be achieved byharnessing the daylight available in a room:artificial lighting is activated or slowly andgradually made brighter only when theavailable daylight is not sufficient. If daylightincidence suffices to meet visual require-ments in the work zone, the artificial lightingcan even be switched off completely. Theless artificial lighting is used, the greater theenergy savings and the lower the CO2

emissions.

Daylight-dependent regulation systems aregenerally designed to maintain a constantlighting level by adjusting artificial lighting inresponse to changes in the incident day-light component. This can be done in vari-ous configurations: the options range fromsimple regulation of individual luminairesthrough regulation of luminaire groups in asystem to lighting management systems(see page 46) and integration of lighting in a building management system.

Natural light comes free of charge. But it isnot quite right to say that incident daylightcosts nothing – because the structuralmeasures needed to admit it all have aprice. Apart from that, additional measuresare often necessary to provide thermal in-sulation and guard against glare. Lightingmanagement systems for dosing daylightand artificial lighting are also somewhatmore expensive to buy than a non intelli-gent lighting installation. However, the extraoutlay is quickly recouped.

Energy pass

In October 2007, an energy pass was intro-duced under the Energy Saving Ordinance(EnEv 2007) to promote economies and cut CO2 emissions. For the first time, thisconsiders the total energy consumption ofa building including lighting (applies to non-residential properties). The basis for calcu-lation is the method set out in DIN V 18599“Energy efficiency of buildings – Calculationof the net, final and primary energy demandfor heating, cooling, ventilation, domestichot water and lighting”. Part 4 deals with the net and final energy demand for lighting.

Lighting quality

It is important to save energy. However,economy drives should not impact on light-ing quality. This is why artificial lighting –and daylight as well, incidentally – needs tobe evaluated on the basis of lighting qualityfeatures. Lighting has to cater to humanneeds, so wherever it is required it needs tobe planned. The workplace is not the onlyplace where lighting needs to be tailored torequirements, meet high visual ergonomicstandards, promote a sense of wellbeingand be good for our health.

Energy-efficient lightingLamps with high luminous efficacy, electronic operating gear, luminaires optimised for optical control, daylight utili-sation and lighting management make for energy-efficient lighting and thus help reduce CO2 emissions.

57

[146] Up to 82 % less energy and a corre-sponding reduction in cost. The comparisonwith an old lighting installation is convincing.

[147] Each individual measure (second bar)produces a minimum saving. Savings can be increased further by ensuring optimal applica-tion.

147

146


58

Information about the extensive and fre-quently updated legislation in place can befound at the portal site of the EuropeanUnion (http://europa.eu/index_en.htm).

EuP Directive

The EuP Directive (Eco-design Directive) isa framework directive setting eco-designrequirements for energy-using products. In Germany, it is transposed into nationallegislation by the Energy-Using Product Act(EBPG). One of the principal objectives of this legislative project is to reduce theenergy consumed during a product‘s life.

Old appliances

The recycling and environmentally accept-able disposal of old electrical and electronicappliances – matters regulated in the Electrical and Electronic Equipment Act(ElektroG) – are also EU-led measures toprotect the environment (WEEE Directive).As far as products covered by the ElektroGare concerned, recycling is a matter formanufacturers/importers, who have the op-tion of assigning the task to a third party.

Discharge lamps are accepted for recyclingin Germany by the industry joint ventureLightcycle Retourlogistik und ServiceGmbH (www.lightcycle.de). Informationabout the recycling of lamps is provided bythe AGLV working group (Arbeitsgemein-schaft Lampenverwertung) of manufactur-ers and lamp recyclers within the GermanElectrical and Electronic Manufacturers‘ Association ZVEI (www.zvei.org).

Luminaires purchased after March 2006 are classed under the ElektroG as “new oldappliances”. They are identified by the“crossed-out waste bin” symbol. All incan-descent lamps and halogen lamps as wellas all luminaires from private householdsare outside the scope of the ElektroG.

Light pollution

Light pollution occurs where light from outdoor lighting installations – e.g. streetlighting systems in residential areas –causes disturbance. Protection against thisis provided in Germany by the Federal Ambient Pollution Control Act (BlmSchG).Any risk of “light pollution” by lighting instal-lations needs to be eliminated at the plan-ning stage.

Neither the Pollution Control Act nor its implementing regulations set out any actualceilings or limits but the German LightingSociety LiTG has published details of usefulmethods of monitoring and assessing lightpollution, together with maximum admissi-ble limits based on them (see page 59). Theambient pollution control committee of Ger-many‘s federal states (Länderausschuss fürImmissionsschutz – LAI) has incorporatedthese methods and ceilings in its guideline“Measurement and assessment of light immissions” and recommends that theyshould be applied by environmental protec-tion agencies; some of Germany‘s federalstates have drafted administrative provi-sions for this in the form of “lighting direc-tives”.

Protection of the starry sky

Light emissions which radiate upwardsfrom densely populated areas and brightenthe night-time sky are known as “lightsmog” – and a number of European coun-tries are trying to pass laws to guardagainst it. The pioneer in protecting the

starry sky was the Czech Republic and Italyand Spain have followed suit. The best way to minimise this kind of light immissionis to ensure that road lighting and exteriorluminaires direct their light only where it isneeded.

Light and insects

Artificial lighting attracts insects, so there is a risk it could interfere with the naturalhabits of nocturnal animals.

Light with a predominantly yellow/orangespectral content is not so attractive to in-sects because their eyes have a differentspectral sensitivity from the human eye.They respond more sensitively to the spec-tral composition of the light from fluores-cent lamps and high-pressure mercuryvapour lamps. Pale moonlight, which in-sects presumably use for orientation, alsoappears much brighter to the insect eyethan to humans. The light cast by a high-pressure sodium vapour lamp, however,appears darker. Orange and red spectralcomponents produce virtually no response.

A summary of what science knows aboutthis subject has been published by the LiTG(see page 59).

Lighting and the environmentRequirements designed to protect the environment are set out mainly by the European Union (EU). In definingthem, the EU identifies four priority areas: climate protection (CO2 reduction), nature and biodiversity, environmentand health, sustainable use of natural resources and waste management.

Standards

DIN EN 1838Lighting applications – Emergency lighting

DIN EN 12193Light and lighting - Sports lighting

DIN EN 12464-1Light and lighting - Lighting of work places,Part 1: Indoor work places

DIN EN 12464-2Light and lighting - Lighting of work places,Part 2: Outdoor work places

DIN EN 12665Light and lighting - Basic terms and criteriafor specifying lighting requirements

DIN EN 13201Street lighting

DIN 5032Photometry

DIN 5035-3Artificial lighting - Lighting of health carepremises

DIN 5035-6Artificial lighting - Measurement and evalua-tion

DIN 5035-7Artificial lighting - Lighting for interiors withvisual display work stations

DIN 5035-8Artificial lighting – Workplace luminaires –Requirements, recommendations andproofing

LiTG – Deutsche Lichttechnische Gesellschaft e.V.

Publication 3.5:1988 „Projektierung von Beleuchtungsanlagennach dem Wirkungsgradverfahren“(Planning lighting systems by the lumenmethod)

Publication 12.2:1996„Messung und Beurteilung von Lichtemmis-sionen künstlicher Lichtquellen“(Measurement and assessment of light im-missions from artificial light sources)

Publication 13:1991 „Kontrastwiedergabefaktor CRF – ein Güte-merkmal der Innenraumbeleuchtung“(Contrast rendering factor CRF – an interiorlighting quality factor)

Publication 15:1997 „Zur Einwirkung von Außenbeleuchtungs -anlagen auf nachtaktive Insekten“(Impact of exterior lighting systems on noc-turnal insects)

Publication 17:1998„Straßenbeleuchtung und Sicherheit“(Street lighting and safety)

Publication 18:1999 „Verfahren zur Berechnung von horizontalenBeleuchtungsstärkeverteilungen in Innen-räumen“(Methods for calculating horizontal illumi-nance in interiors)

Publication 20:2003 „Das UGR-Verfahren zur Bewertung der Direktblendung der künstlichen Beleuch-tung in Innenräumen“(The UGR method of assessing direct glarefrom artificial lighting in interiors)

www.litg.deLiTG, Burggrafenstraße 6, 10787 Berlin

59

Standards, literature


60

[Booklet 14] 48 pages on lighting forthe home. Booklet 14 outlines numer-ous ideas for good lighting for thehome, provides information on everymajor aspect of lighting technologyand indicates suitable lamps and lumi-naires. (Available only in German)

[Booklet 4] 48 pages on office light-ing. Booklet 4 shows how functionallighting can be ergonomically correctand thus be good for our health andperformance.

licht.de publications

[licht.wissen 13] 32 pages on outdoorworkplace lighting. Booklet 13 ex-plains what needs to be consideredfor operations at night. It takes ac-count of the requirements of the newstandard DIN EN 12464 Part 2.

[licht.wissen 03]

40 pages on street lighting. Booklet 3 describes how

“seeing and being seen” works and explains how road

accident figures and crime rates are reduced.

€ 9,–Each booklet!

licht.wissen in English – Free pdf downloads from www.all-about-light.org/en/publications

01 Lighting with Artificial Light (2008)02 Good Lighting for Schools and Educational

Establishments (2003)03 Good Lighting for Safety on Roads, Paths and Squares

(2007)04 Good Lighting for Offices and Office Buildings (2003)

06 Good Lighting for Sales and Presentation (2002)07 Good Lighting for Health Care Premises (2004)08 Good Lighting for Sports and Leisure Facilities (2001)11 Good Lighting for Hotels and Restaurants (2005)12 Lighting Quality with Electronics (2003)13 Outdoor workplaces (2007)

16 Urban image lighting (2002)17 LED – Light from the Light Emitting Diode (2005)18 Good Lighting for Museums, Galleries and Exhibitions

(2006)

[Booklet 17] 28 pages of informationon LEDS. Booklet 17 describes howthe tiny semiconductor crystals work,looks at the technology behind LEDsand LED modules and presents exemplary LED applications.

Gutes Licht für Büros und Verwaltungsgebäude 4 LED – Licht

aus der Leuchtdiode17Ideen für Gutes Lichtzum Wohnen14

Impartial information

licht.de provides information on the advan-tages of good lighting and offers a greatdeal of material on every aspect of artificiallighting and its correct usage. The informa-tion provided is impartial and based on cur-rent DIN standards and VDE stipulations.

licht.wissen

The booklets 1 to 18 of the licht.wissen se-ries of publications (formerly: Information onLighting Applications) are designed to helpanyone involved with lighting – planners,decision-makers, investors – to acquire abasic knowledge of the subject. This facili-tates cooperation with lighting and electricalspecialists. The lighting information con-tained in all these booklets is of a generalnature.

licht.forum

licht.forum is a specialist periodical focusingon topical lighting issues and trends. Gen-erally around 12 pages long, it is publishedat irregular intervals.

www.all-about-light.org

The industry initiative also maintains an In-ternet presence. Its website www.all-about-light.org features a Private Portal and a ProPortal offering tips on correct lighting for avariety of domestic, commercial and indus-trial “Lighting Applications”.

Explanations of technical terms are alsoavailable at the click of a mouse on the but-tons “About Light” and “Lighting Technol-ogy”.

Databases containing a wealth of productdata, a product/supplier matrix and the ad-dresses of licht.de members provide a di-rect route to manufacturers. “Publications”in an online shop and “Links” for further in-formation round off the broad spectrum ofthe lighting portal.

All about light! Imprint

Publisher

licht.de

Fördergemeinschaft Gutes Licht

Lyoner Straße 9. 60528 Frankfurt am Main

Germany

phone: ++49 (0)69 6302-353,

fax: ++49 (0)69 6302-400

[email protected], www.licht.de

Editing

JARO Medien, Mönchengladbach

Realisation of revised new edition

rfw. agentur für kommunikation, Darmstadt

Design

Kugelstadt MedienDesign, Darmstadt

Lith film

Layout Service Darmstadt

Printed by

– no print –

ISBN 978-3-926 193-39-1

4/08/00/IVb

The publication takes account of current DIN standards

(available from Beuth Verlag, Berlin) and VDE stipulations

(available from VDE Verlag, Berlin)

Reprints of licht.wissen 01 with the permission of the

publishers.

Acknowledgements for photographs

Numbering of photos on back page:

1–3 Internationale Lichtrundschau, Eindhoven/Nether-

lands • 16 Fotosearch/Imagestate • 17 and 18

fotolia/Lou Guerrero • 28/29 Fotosearch/Jupiterimages

• 31 and 32 fotolia/Anatoly Tiplyashin • 64 fotolia/

Bonnie C. Marquette • 67 fotolia/Zol.

All other photographs, 3D visualizations and illustrations

courtesy of licht.de members or commissioned by

licht.de.

152 153 154

149 150 151

148

Fördergemeinschaft Gutes LichtLyoner Straße 960528 Frankfurt am MainGermanyTel. +49 (0)69 63 02-353Fax +49 (0)69 63 [email protected]

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