Lighting with Artificial Light

Lighting with Artificial Light The basics of lighting Lighting with Artificial Light page 1

What is light? The visible part of electromagnetic radiation, which is made up of oscillating quanta of energy Speed of light: 2.98 x 10 8 m/s, i.e. around 300,000 km/s Light spectrum: 380 nanometres (violet) to 780 nanometres (red) White sunlight is the sum of all the colours of the light spectrum Coloured objects only appear coloured if their colours are present in the spectrum of the light source. Lighting with Artificial Light page 2

The eye our camera There are around 130 million visual cells in the human eye, divided into two types: rods and cones Rods are sensitive to brightness, Cones are for colour vision Adaptation: adjustment of the eye to higher or lower levels of illuminance Dark adaptation takes longer than light adaptation 80 percent of all the information we receive is provided by our eyes. Fotolia.com: Bonnie C. Marquette Lighting with Artificial Light page 3

From fire to LED Hier könnte eine Bildunterschrift stehen. 300,000 years ago: man starts using fire as a source of heat and light Around 260 B.C.: construction of the Lighthouse of Alexandria 1783: gas is extracted from coal for use in street lights 1879: invention of the incandescent lamp 1880s: appearance of early fluorescent lamps 1995: presentation of the first LED delivering white light Lighting with Artificial Light page 4

Lighting terminology and variables Variable Explanation Unit Abbreviation Symbol Luminous flux Luminous intensity Luminous efficacy rate of light emitted by a lamp luminous flux in one direction luminous flux per watt lumen lm candela cd I lumen/watt lm/w Luminance perceived brightness of a surface candela/ square metre cd/m 2 L Illuminance Reflectance luminous flux on a given surface Ggf. Quellenangabe nicht vergessen luminous flux reflected by a surface lux lx E percent p p Lighting with Artificial Light page 5

Factors of good lighting Visual performance, determined by lighting level glare limitation Visual comfort, determined by colour rendering brightness distribution Visual ambience, determined by direction of light/modelling light colour Lighting quality features are interrelated. Lighting with Artificial Light page 6

Quality features for visual performance Hier könnte eine Bildunterschrift stehen. Lighting level illuminance reflectance (e.g. walls) The lower the reflectance, the higher the illuminance needs to be Glare limitation direct glare reflected glare Glare causes discomfort and can interfere with visual performance Lighting with Artificial Light page 7

Illuminance standards Illuminance is stipulated in standards, e.g. DIN EN 12464-1 for indoor workplaces DIN EN 13201-2 for street lighting Examples of illuminance (measured in lux, lx) office 500 lx car park 15 lx precision engineering 1,000 lx kitchen 500 lx operation cavity 100,000 lx stairs 150 lx By comparison: daylight illuminance cloudless summer s day 100,000 lx overcast winter s day 3,000 lx Lighting with Artificial Light page 8

Illuminance maintained illuminance Soiling and ageing of luminaires, lamps and room surfaces cause the illuminance of an installation to decrease in the course of its operating life. So new installations need to be designed for a higher illuminance (= value on installation). Maintained illuminance values (= average on the assessment plane) are set out in standards. Illuminance must not fall below the maintained illuminance value. Maintenance factors are defined by designers and operators to calculate illuminance on installation. They take account of the type of luminaires and lamps used as well as the risk of soiling and maintenance intervals. Formula for planning: maintained illuminance = maintenance factor x illuminance on installation Lighting with Artificial Light page 9

Glare limitation direct glare Direct glare is caused by excessively high luminance general-diffuse lamps incorrectly positioned luminaires How to avoid glare: shield lamps position luminaires correctly Lighting with Artificial Light page 10

Glare limitation reflected glare Reflected glare is caused by excessively luminous lamps, luminaires or windows at reflective or shiny surfaces (e.g. wet roads, computer screens) Example: luminance limit Positive display VDU, mean luminance 1,000 cd/m 2 How to reduce reflected glare: select correct luminaires and lamps ensure favourable arrangement of light sources reduce luminance of surfaces that are reflected Lighting with Artificial Light page 11

Quality features for visual comfort Ggf. Quellenangabe nicht vergessen Ggf. Quellenangabe nicht vergessen Ggf. Quellenangabe nicht vergessen Harmonious distribution of brightness supports vision by creating a balanced pattern of luminance lends structure to a room Good colour rendering facilitates accurate identification of colours influences the climate and atmosphere of a room The colour rendering index R a indicates how well lamps render natural colours (optimal value R a = 100). Lighting with Artificial Light page 12

Quality features for visual ambience Light colours warm white (< 3,300 kelvin) neutral white (3,300 5,300 K) daylight white (> 5,300 K) Direction of light direct (directional) light diffuse (non-directional) light Modelling gives objects depth emphasises surface structures Tip for agreeable contrasts: balanced mix of diffuse and directional light Lighting with Artificial Light page 13

Light colour and colour rendering characteristics The colour rendering quality of a lamp is determined by the spectral composition of its lamps. Lamps of the same light colour can emit light with a different spectral composition. So it is not possible to draw conclusions about colour rendering from light colour. Colour coding of lamps Every lamp has a colour code. It consists of three digits and indicates the lamp s colour rendering index and light colour 1st digit: colour rendering performance, e.g. 9 for R a range 90-100 2nd + 3rd digit: colour temperature, e.g. 27 for 2,700 K Example: fluorescent lamp with colour code 830 This fluorescent lamp has a good R a index between 80 and 90 and a warm white light colour of 3,000 K. Lighting with Artificial Light page 14

Overview of lamps/light sources Ggf. Quellenangabe nicht vergessen Ggf. Quellenangabe nicht vergessen Ggf. Quellenangabe nicht vergessen There are basically three types of light sources: Thermal radiators: incandescent and halogen lamps Discharge lamps: fluorescent, high- and low-pressure lamps Solid-state light emitters: LEDs und OLEDs (organic light-emitting diodes) All three types are available in a wide variety of models and variants. Lighting with Artificial Light page 15

Light sources: technical variables Hier könnte eine Bildunterschrift stehen. From watt to kelvin Eventuell kurze Bildunterschrift Technical ratings facilitate lamp selection: power rating unit: watt (W) luminous flux unit: lumen (lm) efficiency/luminous efficacy unit: lumen per watt (lm/w) colour rendering unit: colour rendering index (R a ) colour temperature unit: kelvin (K) Light colour and colour temperature warm white < 3,300 K neutral white 3,300 5,300 K daylight white > 5,300 K Ggf. Quellenangabe nicht vergessen Lighting with Artificial Light page 16

Luminaires: arrangement and characteristics 1. Requirements Application, e.g. interior or exterior luminaire Type and number of lamps Structural type, e.g. open/closed luminaire Type of mounting, e.g. recessed luminaire 2. Characteristics lighting characteristics electrical characteristics mechanical characteristics exterior design First plan, then select. Lighting with Artificial Light page 17

Luminaires: technical variables Hier könnte eine Bildunterschrift stehen. Lighting characteristics, e.g. luminous flux distribution luminous intensity distribution luminance distribution light output ratio Electrical characteristics, e.g. electrical reliability ballasts radio interference suppression class of protection degree of protection (Ingress Protection) Lighting with Artificial Light page 18

Luminaires: modern control Operating devices electronic ballasts transformers/capacitors startes and igniters Lighting management Electronic lighting control depending on: daylight incidence precence room use Simple operation, e.g. with A presence detector alone cuts energy consumption by up to 10%.The energy saving with daylight-dependent regulation can be as high as 35%. Lighting with Artificial Light page 19

Basics of planning Hier könnte eine Bildunterschrift stehen. Well-planned lighting takes account of user requirements complies with relevant standards is energy-efficient Information required for planning: room plans/ground plan colours/reflectances (walls, ceilings) function of rooms/visual tasks furnishings/arrangement of machines operating conditions (dust, moisture) for roads: installation geometry and reflective properties of the road surface Lighting with Artificial Light page 20

Lighting costs Lighting costs comprise: initial outlay (acquisition, installation) operating costs Operating costs comprise: maintenance costs (lamp replacement, labour costs) electricity costs Example: Electricity costs Energy-saving lamp (11 Watt) 0.011 kw 8,000 h 0.18 euro = 15.84 euro/year Electricity costs account for as much as 70% of the total costs of a lighting installation. The use of efficient lighting technology saves energy and money. Lighting with Artificial Light page 21

Enery-efficient lighting Factors for energy-saving lighting are: efficient light sources, e.g. LEDs luminaires with a high light output ration and optimal luminous intensity distribution lighting management geared to requirement daylight utilisation Optimal lighting = maximum quality + minimum consumption Savings potential of of interior lighting: up to 75% less electricity Enery consumed for lighting is one of the factors used to assess the energy efficiency of buildings (standard: DIN V 18599). Lighting with Artificial Light page 22

Lighting and the environment EU sets standards In the European Union (EU), requirements have been defined at the highest level for climate protection nature conservation health and safety sustainability Relevant directives include: Ecodesign ErP Directive (Energy related Products) EPBD Directive (Energy Performance of Buildings Directive) The EU aims to reduce its energy consumption by 20% by 2020. Efficient lighting will help achieve this target. Lighting with Artificial Light page 23

Further information Further information on the subject is provided in the booklet licht.wissen 01 Lighting with Artificial Light (62 pages) This and other booklets in the licht-wissen series are available as free pdf downloads at www.licht.de/en More information on lighting: Deutsche Lichttechnische Gesellschaft (LiTG), www.litg.de Standards on the subject of light and lighting: Beuth-Verlag, www.beuth.de Lighting with Artificial Light page 24

Publisher licht.de Fördergemeinschaft Gutes Licht Lyoner Straße 9 60528 Frankfurt am Main licht.de@zvei.org www.licht.de No part of this material (especially photographs and illustrations) may be altered, used, reproduced, displayed or disseminated without the prior consent of licht.de. This does not apply to individual copes for personal, non-commercial use. Lighting with Artificial Light page 25