Fördergemeinschaft Gutes Licht Lighting with Artificial Light 1 1 Fördergemeinschaft Gutes Licht Contents Introduction 1 From nature‘s light ... to artificial lighting 2 / 3 The physics of light 4 / 5 The physiology of light 6 / 7 The language of lighting technology 8 / 9 Quality features in lighting 10 Lighting level - maintained illuminance and luminance 11 Glare limitation - direct glare 12 Glare limitation - reflected glare 13 Harmonious distribution of brightness 14 Direction of light and modelling 15 Light colour 16 Colour rendering 17 Light generation by thermal radiators and discharge lamps 18 / 19 Overview of lamps 20 / 21 01 Luminaires - General requirements and lighting characteristics 22 / 23 Luminaires - Electrical characteristics, ballasts 24 / 25 Luminaires - Operating devices, regulation, control, BUS systems 26 / 27 Review of luminaires 28 / 29 Lighting planning 30 / 31 Lighting costs 32 Measuring lighting systems 33 Lighting and the environment 34 Literature, acknowledgements for photographs. order cards 35 Imprint 36 Information from Fördergemeinschaft Gutes Licht 37 02 1 1 Fördergemeinschaft Gutes Licht Light has always held a special fascination – in art and architecture too. Brightness and shadow, colour and contrast shape the mood and atmosphere of a room or space. They even help define fleeting moments. ooklet 1 of the Information on Lighting Applications series published by Fördergemeinschaft Gutes Licht is Bintended for all those who want to delve into the topic of light and lighting or wish to familiarize themselves with the basics of lighting technology. The present edition (published July 2004) is a revised version of the May 2000 edition taking account of all current standards. It also forms the introduction to a series of publications designed to provide useful information on lighting applications for all those involved in planning or decision-making in the field of lighting. One of the objectives of the series is to promote awareness of a medium which we generally take for granted and use without a second thought. It is only when we get involved in “making” light, in creating artificial lighting systems, that things get more difficult, more technical. Effective lighting solutions naturally call for expertise on the part of the lighting designer. But a certain amount of basic knowledge is also required by the client, if only to facilitate discussion on “good lighting” with the experts. This publication and the other booklets in the series are designed to convey the key knowledge and information about light, lamps and luminaires needed to meet those require- ments. Light is not viewed in these booklets as simply a physical phenomenon; it is considered in all its implications for human life. As the radiation that makes visual contact possible, light 03 plays a primarily physiological role in our lives by influencing our visual performance; it also has a psychological impact, however, helping to define our sense of wellbeing. Furthermore, light has a chronobiological effect on the human organism. We know today that the retina of the eye has a special receptor which regulates such things as the sleep hormone melatonin. Light thus helps set and synchronize our “biological clock”, the circadian rhythm that regulates active and passive phases of biological activity according to the time of day and year. So the booklets published by Fördergemeinschaft Gutes Licht not only set out to provide information about the physics of light; they also look at the physiological and psychological impact of “good lighting” and provide ideas and advice on the correct way to harness light for different applications – from street lighting to lighting for industry, schools and offices, to lighting for the home. Illustrations: 01 “Café Terrace at Night” (1888), Vincent Van Gogh (1853 - 1890), Rijksmuseum Kröller-Müller, Otterlo, Netherlands 02 “The Artist‘s Sister with a Candle” (1847), Adolf Menzel (1815 – 1905), Neue Pinakothek, Munich, Germany 03 “The Sleepwalker” (1927), René Magritte (1898 – 1967), privately owned 04 Installation, Maurizio Nanucci (1992) 04 1 1 Fördergemeinschaft Gutes Licht From nature’s light ... to artificial lighting 05 06 ight is life. The relation- ñ The light of the sun, vene- ñ The light of the moon and so for most of the time we ship between light and rated in ancient cultures as stars has only 1/500,000th of live in “chronobiological dark- a god, determines the pulse the intensity of sunlight. But Llife cannot be stated of life and the constant yet the sensitivity of our eyes still ness”. The consequences more simply than that. subtly changing alternation of enables us to see. are troubled sleep, lack day and night. of energy, irritability, even Most of the information we severe depression. receive about our surround- Insufficient light or darkness Lighting level and light colour, ings is provided by our eyes. gives rise to a sense of modelling and switches As we said above, light is life. We live in a visual world. The insecurity. We lack informa- from light to dark impact on Good lighting is important for eye is the most important tion, we lose vital bearings. momentary sensations and seeing the world around us. sense organ in the human Artificial lighting during the determine the rhythm of our What we want to see needs body, handling around 80% hours of darkness makes us lives. to be illuminated. of all incoming information. feel safe. Good lighting also affects the Without light, that would In sunlight, for instance, illu- way we feel, however, and be impossible – light is the So light not only enables us to minance is about 100,000 thus helps shape our quality medium that makes visual see; it also affects our mood lux. In the shade of a tree it is of life. perception possible. and sense of wellbeing. around 10,000 lux, while on a moonlit night it is 0.2 lux, and even less by starlight. People nowadays spend most of the day indoors – in illuminances between 50 and 500 lux. Light sets the rhythm of our biological clock but it needs to be relatively intense to have an effect on the cir- cadian system (> 1000 lux), 07 08 2 3 Fördergemeinschaft Gutes Licht 09 10 round 300,000 years ñ Advances in the develop- ñ For the majority of people started on electric arc lamps ago, man began to ment of electric discharge today, life without artificial – fuelling research which lamps, combined with modern lighting would be unimagi- Ause fire as a source of luminaires, has led to high- nable. acquired practical signifi- warmth and light. The glowing performance lighting systems. cance in 1866 when Werner flame enabled people to live Siemens succeeded in gener- in caves where the rays of the ating electricity economically sun never penetrated. with the help of the dynamo. But the real dawn of the age The magnificent drawings in of electric light came in 1879, the Altamira cave – artworks with Thomas A. Edison‘s “re- dating back some 15,000 invention” and technological years – can only have been application of the incan- executed in artificial light. The descent lamp invented 25 light of campfires, of kindling years earlier by the German torches and oil and tallow clock-maker Johann Heinrich lamps radically changed the Goebel. way prehistoric man lived. With each new light source – But light was not only used from campfire and kindling to in enclosed spaces. It was candle and electric light bulb also harnessed for applica- – “luminaires” were devel- tions outdoors. Around 260 oped to house and harness BC, the Pharos of Alexandria 11 the new “lamps”. In recent was built, and evidence from decades, lamp and luminaire 378 AD suggests there were development has been par- “lights in the streets” of the ticularly dynamic, drawing ancient city of Antioch. on the latest technologies, new optical systems and new Ornamental and functional materials while at the same holders for the precious light- time maximising economic giving flame appear at a very efficiency and minimising early stage in the historical environmental impact. record. But the liquid-fuel lamps used for thousands of years underwent no really major improvement until Aimé Argand‘s invention of the cen- tral burner in 1783. That same year, a process developed by Dutchman Jan Pieter Minckelaers enabled ï For more than 2,000 years, gas to be extracted from artificial lighting has illumi- coal for streetlamps. Almost nated the night and provided simultaneously, experiments security and bearings for human beings. 12 2 3 Fördergemeinschaft Gutes Licht The physics of light 13 14 an has always been ñ Within the wide range of ñ With the aid of a prism, fascinated by light electromagnetic radiation, „white sunlight can be split visible light constitutes only up into its spectral colours. Mand has constantly a narrow band. striven to unravel its myster- ies. History has produced various theories that today strike us as comical but than 5 billion years from the In a further experiment, Max Planck expressed the were seriously propounded most distant spiral nebulae. Newton directed the coloured quantum theory in the for- in their time. For example, rays onto a second prism, mula: since no connection could be Different theories of light from which white light once discerned between a flame enable us to describe again appeared. This was and the object it rendered observed regularities and the proof that white sunlight Ε = h • ν visible, it was at one time sup- effects. is the sum of all the colours posed that “visual rays” were of the spectrum. The energy E of an energy projected by the eyes and The corpuscular or particle quantum (of radiation) is reflected back by the object. theory of light, according to In 1822, Augustin Fresnel proportional to its frequency Of course, if this theory were which units of energy (quanta) succeeded in determining v, multiplied by a constant h true, we would be able to see are propagated at the speed the wavelength of light and (Planck‘s quantum of action).