Light in its third dimensionThe biological aspect of lighting design for better quality of life

www.osram.com/quality-of-life

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THE DIMENSIONS OF LIGHT

The discovery of human well-beingUp to now, the principal function of artifi cial light was to enable our visual perception. Knowledge gained through scientifi c research and embodied in standards and laws has provided architects and engineers with a basis for designing lighting systems.

Recent studies have shown however that light has an extra dimension. It stimulates cognitive centers in the brain and drives our inner clock. Light therefore has a tremendous infl uence on our well-being. Lighting solutions from OSRAM make use of the positive effects and, as part of a coordinated lighting concept, enhance concentration, performance, and quality of life, for example at the workplace or in school.

The three dimensions of light.

The 1st dimension: The theory of optimum vision with the aid of artifi cial light sources; a corpus of legislation and standards (e.g. DIN EN 12464) on the basis of scientifi c fi ndings.

The 2nd dimension:Implementation of this theory in the design and construc-tion of lighting systems that improve human perception.

The 3rd dimension:Research into the biological effects of light and the appli-cation of these effects for improved well-being, greater powers of concentration and better quality of life overall. Many years of experience in light and lighting have en-sured that OSRAM understands better than almost anyone

just what a fundamental role the right light has on our well-being and our level of performance – and how best to use it at the workplace and similar applications. To make sure that artifi cial lighting comes as close to natural daylight as possible, OSRAM offers a variety of options and products not only to upgrade existing lighting systems but also to provide the best possible equipment for new projects.

Individual optionsReplacing the luminaire or the light source, using daylight systems or light management systems – the right solutionfor everyone.

Extensive product rangeTraditional lighting systems (TLS) and pioneering LED solutions – innovative luminaires, light sources and control gears in every lighting technology.

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THE DIMENSIONS OF LIGHT

CONTENTS

Scientifi c fi ndings 4

The basic principles of a biological lighting concept 6

Daylight systems and luminaires 10

Lighting management systems (LMS) 12

Fluorescent lamps and control gear 14

LED modules and control gear 16

Glossary 18

Bibliography 19

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We control light.But light also controls usWe need good quality light in order to see well. But light has a much more far-reaching signifi cance. Without our being aware of it, daylight controls many biological processes in our bodies and therefore our internal clock. Light also dictates whether we are active or tired, whether we can concentrate or not and whether we feel good or not.

Biological rhythms dictate when we wake up, when we be-come tired and when we fall asleep; they even have an ef-fect on our body temperature and much more. The control center for our internal clock is in our brain and is heavily in-fl uenced by light. Although our “circadian rhythm” is basi-

cally determined by our genetic makeup, our internal clock has to be resynchronized by daylight each and every day. Without light as the prime regulator our internal clock soon goes out of sync. As a result we may suffer from sleep dis-orders, chronic fatigue and in the worst case depression.

Circadian rhythm, hormone secretion:There are two hormones in humans that are

responsible for signaling in the circadian rhythm:

melatonin, which is released in the evening

when it gets darker and which promotes sleep,

and cortisol, which is the counterpart of melatonin

and an indicator of the level of human activity.

SCIENTIFIC FINDINGS

Cortisol level Melatonin level

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Light not only infl uences our rhythms it also stimulates the response centers in our brains. It acts on theseresponse centers through a third photoreceptor in thehuman eye which was discovered only a few years ago. The effect of light of natural daylight quality with a highblue component is much stronger than light from an in-candescent lamp with its high red component. Studies have shown that reaction times can be improved by in-creasing the blue component in light. This means that we feel more productive in better daylight and we are more able to concentrate. Light also causes serotonin to be produced, a neurotransmitter known as the “happy hor-mone” because it is a contributor to feelings of well-be-ing and happiness.

Light that is inspired by natural daylight is not just bright-er it also stimulates us. The cognitive centers in the brain and the control center for our internal clock are moresensitive to light with a pronounced blue component, so this light makes us more alert, more attentive and moreable to concentrate on our work during the day.

And our recovery during the night does not suffer as a result – quite the opposite. Biologically effective light during the day increases secretions of the melatonin hormone during the night. Melatonin is the body’s own signal for darkness and promotes sleep. Appropriate light during the day stabilizes the circadian cycle, helping us to be active during the day and sleep better during the night. The consequences are obvious – more restful nights as the body needs less time to get to sleep and goes into deeper sleep. People who get a good night’s sleep are capable of better performance at work during the day.

Artifi cial daylight (spectrum and dynamics) at the work-place therefore has a two-fold positive effect on perfor-mance and well-being. Modern light – developed on the basis of recent scientifi c fi ndings – can make work more pleasurable and more successful.

Light affects our body:Daylight with a high blue compo-

nent has an activating effect and

boosts concentration. This is be-

cause it stimulates the receptors

in the eye and therefore the con-

trol center in the brain to a much

greater extent than light with a

high red component.

Prof. Dr. Jürgen Staedt, Mental health consultant, Berlin:“A daily dose of bright light with a suffi ciently high blue component

is extremely advisable, particularly in the dark winter months, for

stabilizing our day/night cycle and therefore for our general well-

being. In general medicine we are now using light more and more

to achieve improvements in the general moods of our patients.”

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BASIC PRINCIPLES OF A BIOLOGICAL LIGHTING CONCEPT

Good light has to be designed correctlyThe biological effect is greatest when light comes from a light source with a large surface area and from above. Indirect lighting in which light is refl ected from a large bright surface such as a white wall therefore has a stronger impact than the concentrated light from a spotlight that illuminates only a small area.

This is because the photoreceptors in the eye are distrib-uted evenly over the retina. The signal to the control center in the brain – and therefore the biological effect – is great-est when as many photoreceptors as possible are stimu-lated simultaneously. Such a full-scale impact on the retina can only come from a correspondingly large area in ourfi eld of vision.

Biological effect of light on the human eye:The activating effect of light depends not only

on the light color but also on the size of the light source

(e. g. indirect lighting) and the correct angle of incidence

of the light beam in the eye.

0° to ~30°no effect

~30° to ~45°moderate effect

45° to ~90°good [acv optimum]

90° bis 180°not desirable(risk of glare)

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BASIC PRINCIPLES OF A BIOLOGICAL LIGHTING CONCEPT

Ceilings and walls with bright surfaces can therefore be used as large secondary refl ectors to access the relevantphotoreceptors in the human eye to maximum effect.

The luminances of the surfaces in a room must not exceedthe permitted values however, otherwise there may be undesirable direct and refl ex glare. The best luminaireseither provide indirect light off wall and ceiling surfaces orlarge refl ecting surfaces themselves.

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Suitable luminaires are selected and arranged according to these criteria. Lighting design based on biological aspects therefore makes special demands on the lumi-naires and the distribution of light in the room.

Luminaires tailored for every room.In standard rooms, luminaires integrated in the ceilingparallel to the walls can illuminate the wall surfaces. 1

Plasterboard facings with integrated indirect lighting serve the same purpose. 2

In very large rooms with relatively low ceilings the wallsurfaces are not as important – the ceiling should act as the refl ective surface here. “Light ceilings” made of trans-lucent materials and backlit with light sources with a high blue content (8000 K) offer excellent results here. 3

If light ceilings are not possible, luminaires with a strong element of indirect light can be used to illuminate the ceiling with biologically effective light. 4

Pendant luminaires with large refl ecting surfaces or shelves in which the light is visible help in factories and large en-closed spaces with high ceilings. 5

Every room presents its own challengesThe rooms in which we live, work, learn or relax are all very different. Professional lighting design takes into account the size of the room, the ceiling height, the amount of daylight entering the room and obviously the main activities that will be carried out in the room.

BASIC PRINCIPLES OF A BIOLOGICAL LIGHTING CONCEPT

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DAYLIGHT SYSTEMS AND LUMINAIRES

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DAYLIGHT SYSTEMS AND LUMINAIRES

It is important to get the right mix:natural daylight and artifi cial lightNatural daylight is the ideal light for human vision. It covers the entire color spectrum so objects appear in their natural colors. It helps our bodies navigate through time and space. But the use of daylight also has its disadvantages, such as glare and unwanted heat.

To avoid these adverse effects Siteco, a subsidiary of OSRAM AG, has developed daylight systems based on prism and louver technology that not only create a dynamic lighting mood with natural color rendering but also effectively protect against excessive sun and heat. What’s more, by using available daylight it is possible to achieve signifi cant reductions in energy consumption.

But even with daylight systems there generally needs to be some additional artifi cial light. The more closely theartifi cial light is matched to natural daylight the less stress-ful it is for people and therefore the greater the sense of well-being.

At workplaces in particular, high-quality lighting with balanced contrasts is essential for long periods of con-centration. The Mira® luminaire from Siteco, for example, combines direct distribution of light with indirect ceilingillumination to create a pleasant atmosphere in a room.The cover with its sophisticated microprism technology ensures uniform glare-free light and a high level of visualcomfort.

This makes the luminaire ideal for mounting directly above workplaces. It also means that the luminaires can be arranged irrespective of the layout of the room, giving enormous fl exibility in room design. The luminaires are available in recessed, surface-mounted and pendant versions.

Energy savings can be optimized by using daylight with daylight systems from Siteco and appropriate luminaires and light management systems fromOSRAM.

Top: Daylight prism systemshave a barrier surface from which all the

light that hits it is refl ected. Light from other

angles can pass through.

Bottom: Daylight louver systemsuse their special form and high-quality

refl ective surfaces. The direct hot sunlight

is refl ected; the cool diffused sky light is

allowed through.

Mira®: Thanks to a completely new prism

structure this Intelligent luminaire achieves

extremely high levels of effi ciency

and produces a unique radiant effect

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Everything under control: daylight simulation and lighting control with OSRAM LMSAn ideal lighting system uses as its reference the natural changes of daylight in terms of intensity, color temperature and dynamics. OSRAM’s light management systems can simulate natural daylight and control room lighting so that the right amount of the right light is available at all times, promoting a sense of well-being.

EASY Color Control – light to suit your moodDaylight boosts human activity and promotes a feeling of well-being. For people working in windowless rooms natural daylight must be replaced by artifi cial lighting. With the EASY Color Control System the lighting can be con-trolled so that the intensity, color temperature and dynam-ics of the light correspond to those of natural daylight. The luminaires are controlled in a harmonious way so that the changes are imperceptible. The results however are very noticeable indeed. There are increases in the performance,motivation and effi ciency of employees.

LIGHT MANAGEMENT SYSTEMS (LMS)

Total cable length max. 100 m

USB connection

DALI® EASY III DALI® EASY III

QTi DALI® QTi DALI®

Configuration software

EASY pushbutton coupler

Timer switch

Synchronization of up to 16 DALI® EASY III units per EASY system

White fluorescent lamps

2 70

0K

8 00

0K

2 70

0K

8 00

0K

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MULTIeco – always enough light when it’s neededNatural light changes over the course of the day so it is important to adjust the room lighting to take account of these changes. In daylight-dependent and motion/pres-ence-dependent lighting control with MULTIeco the availa-ble daylight in a room is supplemented as required by artifi cial light from luminaires equipped with dimmable electronic control gear. Light sensors detect the lighting level comprising artifi cial light and natural daylight. The luminaires in the room are controlled according to their position in the room and the amount of available daylight so that a predefi ned lighting level is maintained. Relevant standards and illuminance values can be used to defi nethe optimum lighting for concentrated work. Users can set the lighting at any time to a level that meets their specifi c needs. If a motion/presence sensor is also used the light-ing is automatically switched on when someone enters an empty room and switched off when the last person leaves. This makes optimum use of available daylight and achieves maximum energy savings.

For more information go to: www.osram.com/lms-easy and www.osram.com/lms-multieco.

LIGHT MANAGEMENT SYSTEMS (LMS)Li

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* Non-dimmable QT, HT and OT control gear ** Suitable power supply required

Standard switchSensors

LS/PDMULTI 3

LS/PD MULTI 3 FL

LS/PD MUL-TI 3 B

LS/PD MULTI 3 CI

DALI® MULTIeco DIM MULTIeco MULTIeco

1...10 V DIM

LS/PDMULTI 3 A

LS/PD MULTI3 A-W

QTi DALI® HTi DALI® OTi DALI® 75 QTi DIM HT 1…10 V OT DIM**

Switching contact

**QT OT

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Quality of light – white on whiteWith a broad selection of color temperatures from 2700 K to 8000 K the high-quality white LUMILUX® fl uorescentlamps from OSRAM are the perfect choice for lighting systems that are based on natural daylight in terms of inten-sity, color temperature and dynamics.

In areas without windows and even in rooms with windowsthe amount of light entering the room is often not sufficient for concentrated work. For a large part of the day the available daylight has to be supplemented with artificial light.

SKYWHITE® fluorescent and compact fluorescent lamps with light color 880 (color temperature 8000 K and good color rendering) are characterized by their impressive quality of light. They emit a large proportion of “blue” light in the wavelength range from 410 to 480 nm and therefore

FLUORESCENT LAMPS AND CONTROL GEAR

1. SKYWHITE® fl uorescent lamps: Natural daylight thanks to

a high blue content and a color

temperature of 8000 kelvin.

2. QTi DALI®: The intelligent elec-

tronic control gear with superior

dimming technology.

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come very close to the character of natural daylight. In ad-dition, SKYWHITE® improves contrast and reduces visual fatigue – and that is known to boost mental and physical performance. SKYWHITE® lamps also offer high luminous flux and good efficiency (up to 85 lm/W).

QTi DALI® electronic control gear from OSRAM with supe-rior dimming technology is the perfect platform for such applications. Intelligent control of electrode preheating during dimming ensures that the lamps achieve their maxi-mum lifetime.

For more information go to: www.osram.com/fl uorescent and www.osram.com/ecg.

Paul von Rickenbach, owner of the Muotathal furniture factory in Switzerland:

“We made the change to OSRAM fl uorescent lamps. The

SKYWHITE® light color of 8000 K is the perfect supple-

ment to natural daylight. After just two days of getting

used to the new lighting system none of our employees

wanted to do without this cool blueish light. And our em-

ployees have reported that they feel less tired, have fewer

headaches and can concentrate much better.”

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Lighting design unlimitedExtremely effi cient and highly fl exible with white LED modules and OT EASY 60 II control gear – OSRAM LED technology gives lighting designers and planners more freedom than ever before. In conjunction with intelligent light management systems it is possible, for example, to create ideal dynamic lighting scenes with color effects and to develop innovative lighting concepts with dynamic daylight simulation to improve the quality of life.

In rooms without suffi cient natural light in particular innovative LED technology from OSRAM can be used to achieve highly effi cient daylight simulation. White LED modules are available from OSRAM in different designs and color temperatures from 2700 K to 6700 K; here are some examples for different applications.

The fl exible DRAGONchain® Tunable White LED chain is ideal for backlighting large light boxes or light ceilings. Each individual module in the chain includes two warm white LEDs at 2700 K and two cold white LEDs at 6500 K. When controlled by a light management system the effects of daylight can be simulated.

LINEARlight Flex® ShortPitch units are perfect for instal-lations in which there is little available space. The LED module does not need additional heat removal, is only 8 mm wide and has extremely small spacings between

the individual LEDs of only 8.33 mm. These features make the LINEARlight Flex® ShortPitch ideal for edge injection of light into diffused or semi-transparent material or milled acrylic. The combination of LINEARlight Flex® ShortPitchLED modules in light color 827 and light color 865, con-trolled by light management systems, also offers harmoni-ous daylight simulation.

The various OPTOTRONIC® units are perfectly matched to OSRAM LED modules to ensure durable trouble-free oper-ation. The OT EASY 60 II unit is ideal for dynamic daylight simulation with white LED modules.

For more information go to: www.osram.com/led and www.osram.com/ecg.

LED MODULES AND CONTROL GEAR

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LED MODULES AND CONTROL GEAR

1. DRAGONchain® Tunable white:Stepless control for outstanding

daylight simulation

2. LINEARlight Flex® ShortPitch:Slim effi ciency thanks to extremely small

spacings between individual LEDs.

3. OPTOTRONIC® OT EASY 60 II:Ideal control gear for dynamic daylight

simulation

Effi cient and eco-friendlyDaylight-dependent lighting systems from OSRAM are extremely effi cient. Fluorescent and compact fl uorescent lamps and LEDs from OSRAM are some of the most eco-nomical and durable light sources available. In conjunction with the appropriate electronic control gear their effi ciency and longevity are further improved. By using available daylight and the presence of a person or persons in the room as control elements (in conjunction with the pres-ence sensors of a light management system) it is possible for the lamps to remain on only for as long and as brightly as is absolutely necessary. As a result, operating costs are signifi cantly reduced. This also represents an enormous relief for the environment. Resources are protected and CO2 emissions are reduced.

For more tips and advice for your lighting solutions go to: www.osram.com/global-care and www.osram.com/light-consultant

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GLOSSARY

Action spectrumThis is the spectral sensitivity for an effect triggered by light. There are action spectra for a wide variety of biological effects, for example for the occurrence of sunburn due to UV or for the formation of vitamin D due to UV-B. The action spectrum for the sensitivity of the eye is the v(λ) curve. The action spectrum for biological effects in accordance with the new German draft standard DIN V 5031-100 corresponds to the action spec-trum for night-time melatonin suppression by light. It is now assumed that the other biological effects of light essentially follow this action spectrum.

Circadian rhythm A biological cycle with a period of approximately 24 hours (from the Latin circa = about, dies = day). Circadian rhythms can be found in almost all life forms – animals and plants. Not only the essential functions of the en-tire organism but almost every individual organ and even every individual cell have their own genetically predefined circadian rhythm. The interplay of these individual cells and organs produces the outwardly visible or measurable circadian rhythms for the entire organism. Light is the most important “zeitgeber” for the circadian rhythm. It is the effect of light that synchronizes the rhythm to the 24 hours of a day.

Dispersion material propertiesProperties of translucent materials for scattering the light shining through them. The example of a change in light due to filtering is independent of the type of light source. It is stronger if the light has a high blue contentbut often tends to be inconspicuous and can often only be detected through precise measurements. Particular attention must be paid to the aging of plastics under the influence of high temperatures or UV radiation because even slight yellowing can lead to a significant filter effect and therefore to reduced biological effectiveness. A comparable effect with indirect lighting occurs if the wall material or color does not reflect bluelight well.

Field of viewThis is the extent of the observable world that lies before our eyes and can be formed on the retina without moving our eyes. The field of view of an eye is limited by the size and optical properties of the components of the eye (cornea, lens, iris, vitreous body) and the population of the retina with visual cells (cones and rods). The fields of view of our two eyes over-lap significantly.

Ganglion cellsThese are nerve cells that are responsible for processing and transmitting nerve impulses from receptor cells. With regard to the biological effect of light the retinal ganglion cells are of particular importance. For a long time it was assumed that these ganglion cells were responsible only for processing information from the visual receptors – the cones and the rods. Ganglion cells for example take the mix of signals from red and green-sensitive cones and produce a signal for yellow that is transmitted to the brain. It is this ability to mix signals that enables us to perceive all the different colors. Around 2 to 3 % of these ganglion cells are them-selves sensitive to blue light. They act as “third photoreceptors”.

Internal clockAlso known as the biological or physiological clock. The internal clock is the central element of the timing system and is located in the SCN. Its progress is genetically predetermined but is essentially influenced by light. Light is consequently the most important “zeitgeber” for the internal clock; it synchronizes the internal clock with the external day. The status of the internal clock, in other words the phase, can be largely deduced from the melatonin level curve.

ipRGC intrinsic photosensitive retinal ganglion cells or melanopsin-carrying ganglion cells.These nerve cells in the retina contain the photopigment melanopsin and have their own (intrinsic) sensitivity to light. They communicate the pres-ence of biologically effective light in the environment to the brain.

MelanopsinThis is a photopigment that is responsible for the light sensitivity of some of the retinal ganglion cells (ipRGC). Its sensitivity can be described by the action spectrum for melatonin suppression, with a maximum at around 464 nm – in other words at the blue end of the spectrum. Through the absorption of light, melanopsin transmits the nerve signals that lead to biological effects. Opsin is the general term for a light-sensitive pig-ment (photopigment) in the eye. The pigment undergoes a change when it absorbs photons (quantums of light), releasing a chemical signal chain at the end of which is a conversion to electrical signals in the nervous system. The pigment in the rods for light/dark vision is rhodopsin; the pigments in the cones are iodopsin, porphyrosin and cyanopsin.

Melatonin (suppression)Melatonin is the most important hormone of the pineal gland and can be described as the body’s signal for the night-time darkness. It promotessleep in humans and activity in nocturnal animals. Melatonin is produced and stored in the pineal gland from serotonin, and is released in the night, but only in the dark. Light causes secretion of melatonin to be sup-pressed. If no melatonin is released the level of melatonin in the blood-stream falls as a result of decomposition processes. As melatonin is the most important measurable marker for the circadian phase of the internal clock the melatonin-suppressing effect is generally equivalent to the cir-cadian effect, i.e. the biological effect of light on the internal clock.

PhotoreceptorsThese are light-sensitive sensory cells that convert quantums of light (photons) into the electrical signals for the nervous system. The photore-ceptors in the retina of the human eye are called cones, rods and melan-opsin-carrying ganglion cells. The cones are responsible for color vision. They are at their greatest density in the center of the eye, know as the macula lutea or yellow spot. This is the area of the retina that provides thegreatest spatial resolution. The rods are responsible for light/dark vision and have a greater sensitivity than cones. They are therefore important for night vision. They are mainly found at the periphery of the field of view.The melanopsin-carrying ganglion cells are not considered to be visual cells as they do not transmit images to the central nervous system but merely provide brightness information for controlling the biological effects of light.

Pineal glandThe pineal gland is also known as the pineal body, corpus pineale or epiphysis. The pineal gland is located in the center of the brain and pro-duces the hormone melatonin which is secreted into the bloodstream during the hours of darkness.

RetinaThis is the layer of cells on the back wall of the eye that contains the visual cells and the information-processing nerve cells, including gangli-on cells.

SCNSuprachiasmatic nucleus: a collection of several thousand nerve cells situated above (supra) the intersection of visual nerves (chiasma). Com-

10,90,80,70,60,50,40,30,20,10

c(λ)

V(λ)

380 420 460 500 540 580 620 660 700 740 780 Circadian sensitivity – humans [nm] Visual eye sensitivity – humans Filter absorption

c(λ)

V(λ)

10,90,80,70,60,50,40,30,20,10

380 420 460 500 540 580 620 660 700 740 780Circadian sensitivity – humans [nm]Visual eye sensitivity – humans

Left graphic: Spectrum of a fl uorescent lamp, light color 880, acv = 1;Φ= 4000 lm at 25° (54 W).

Right graphic: Change in the spectrum with reduced spectral transmission at the blue end of the spectrum through fi lters such as plastic materials.

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REFERENCES

monly referred to as the central internal clock. Each of the nerve cells inthe SCN has its own rhythm. Normally the internal clocks of these cells are in synchronism and form the zeitgeber signal for the rhythmic pro-cesses in the body.

Seasonal affective disorder (SAD)Also known as winter depression. Many people suffer mood changes during the winter months which may even be serious enough to qualify as depression. Triggering factors for SAD are generally given as short daylight hours and low light levels during the “dark season”. Other (endogenous) factors must also be considered as the causes of winter depressions. Phototherapy with very bright light helps in many cases. Sufficiently bright light during the day can also prevent the onset.

Third photoreceptorThese are sensory cells in the human eye that transmit information about the brightness of the surroundings via the SCN (suprachiasmatic nucleus) to the brain and, for example, influence the production and secretion of the hormone melatonin. Studies by Brainard have shown that these cells are sensitive to light at the blue end of the spectrum (Brainard 2001). In 2002 Berson identified the ganglion cells containing melanopsin in the retina as the cells responsible (Berson 2002). In addition to their functionin processing stimuli for visual signals they have their own (intrinsic) sen-sitivity to light. The light sensitivity of the retinal ganglion cells is approxi-mately factor 100 less than that of the cones responsible for color vision.

ZeitgeberZeitgeber is the German word for timer. It is used to denote any factor that may set the internal clock. The most important zeitgeber is light, which acts on the SCN through the eye via the retinohypothalamic tract.The central internal clock in the SCN controls a large number of circadianrhythms. Other (peripheral) zeitgebers are in the liver for example and these too control local circadian rhythms.

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