Lighting with Artificial Light - The basics of lighting
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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 108 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 © licht.de
of the light spectrum
Coloured objects only appear coloured if their colours are
present in the spectrum of the light source.
© licht.de
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
© licht.de
Lighting with Artificial Light | page 4
Lighting terminology and variables
Variable Explanation Unit Abbreviation Symbol
Luminous flux rate of light emitted lumen lm
by a lamp
Luminous intensity luminous flux in one candela cd I
direction
Luminous efficacy luminous flux per lumen/watt lm/W
watt
Luminance perceived brightness candela/ cd/m2 L
of a surface square metre
Illuminance luminous flux on a Ggf. Quellenangabe nicht vergessen lux lx E
given surface
Reflectance luminous flux percent p p
reflected by a surface
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.
© licht.de
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
© licht.de
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
© licht.de
Lighting with Artificial Light | page 10Glare 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/m2
How to reduce reflected glare:
select correct luminaires and lamps
ensure favourable arrangement of light sources
reduce luminance of surfaces that are reflected
© licht.de
Lighting with Artificial Light | page 11Quality features for visual comfort
Ggf. Quellenangabe nicht vergessen Ggf. Quellenangabe nicht vergessen Ggf. Quellenangabe nicht vergessen
© licht.de © licht.de © licht.de
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 Ra indicates how well lamps render natural colours
(optimal value Ra = 100).
Lighting with Artificial Light | page 12Quality 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
© licht.de © licht.de
Tip for agreeable contrasts: balanced mix of diffuse and directional light
Lighting with Artificial Light | page 13Light 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 Ra 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 Ra index between 80 and 90 and a warm
white light colour of 3,000 K.
Lighting with Artificial Light | page 14Overview of lamps/light sources
Ggf. Quellenangabe nicht vergessen Ggf. Quellenangabe nicht vergessen Ggf. Quellenangabe nicht vergessen
© licht.de © licht.de © licht.de
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 15Light 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 (Ra)
colour temperature unit: kelvin (K)
Ggf. Quellenangabe nicht vergessen
Light colour and colour temperature
warm white < 3,300 K
neutral white 3,300 – 5,300 K
daylight white > 5,300 K
Lighting with Artificial Light | page 16Luminaires: 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.
© licht.de
Lighting with Artificial Light | page 17Luminaires: 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)
© licht.de
Lighting with Artificial Light | page 18Luminaires: 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%. © licht.de
Lighting with Artificial Light | page 19Basics 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
© licht.de
Lighting with Artificial Light | page 20Lighting costs
Lighting costs comprise:
initial outlay (acquisition, installation)
operating costs
Example: Electricity costs
Energy-saving lamp (11 Watt)
Operating costs comprise:
0.011 kW 8,000 h 0.18 euro =
maintenance costs (lamp replacement, labour costs) 15.84 euro/year
electricity costs
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 21Enery-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 22Lighting 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 23Further 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 24Publisher
licht.de
Fördergemeinschaft Gutes Licht
Lyoner Straße 9
60528 Frankfurt am Main
licht.de@zvei.org
www.licht.de
© 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.
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