LIGHTING DESIGN :FUNDAMENTALS AND
PRESENTED BY: ZISHAN IBRAHIM.
BASIC CONCEPTS/ PROPERTIES OF LIGHT.
PHOTOMETRIC QUANTITIES: MEASURING LIGHT.
LAMPS: INCANDESCENT, FLOURESCENT …..
QUANTITY AND QUALITY OF LIGHT.
LIGHTING CONTROL SYSTEMS.
CURRENT STATE OF ART EUIPMENTS AND PRACTICES.
WHAT IS LIGHT:
• WHAT WE PERCEIVE AS LIGHT IS A NARROW WAVELENGTH
BAND OF ELECTROMAGNETIC RADIATION FROM 380 TO 780 nm.
• THIS ENERGY RADIATION SHOWS DUAL CHARACTERISTICS: IT
CONSISTS OF ENERGY PARTICLES PHOTONS BUT ALSO SHOWS
TRANSVERERSE WAVE MOTION.
• THE WAVELENGTH DETERMINES ITS COLOUR.
• THE HUMAN’S EYE SENSITIVITY VARIES WITH WAVELENGHT , IT
IS GREATEST AROUND 550 nm (YELLOW).
• MATERIALS W.R.T LIGHT CAN BE REFFERED TO AS :
TRANSPARENT, OPAQUE AND TRANSLUCENT.
• LIGHT INCIDENT ON A SURFACE IS DISTRIBUTED IN
THREE WAYS : REFLECTED, ABSORBED AND
• SOME IMPORTANT PROPERTIES OF THE OBJECT ARE
DESCRIBED BY : REFLECTANCE-R, ABSORBANCE-A AND
IN ALL CAES
Basic parameters used in lighting
Luminous flux – Luminous intensity – Illuminance – Luminance.
The intensity of light source is
measured in units of candella
(CD.), defined as intensity of 1/60
sq. cm. sphere of a black body at
melting pt. temp.of platinum.
Measured in lumens (lm.)
One lumen is flow of light emitted by
a unit intensity point source, within
unit solid angle.
As sphere subtends 4∏ (12.56) at its
centre , I cd. Source emits 12.56 lm.
In all directions.
Amount of lux falling on unit area
lm/m2 which is lux.
The luminance is the only
basic lighting parameter that
is perceived by the eye.
It specifies the brightness of
a surface and is essentially
dependent on its reflectance
(finish and colour).
• Colour is the way we distinguish different wavelengths of light.
• It involves both the spectral characteristics of the light itself, the spectral
reflectance of the illuminated surface as well as the perception of the
• The colour of a light source depends on the spectral composition of the
light emitted by it.
• The apparent colour of a light reflecting surface, on the other hand, is
determined by two characteristics: the spectral composition of the light by
which it is illuminated, and the spectral reflectance characteristics of the
• A coloured surface is coloured because it reflects wavelengths selectively.
The spectral reflectance of red paint, for example, shows that it reflects a high
percentage of the red wavelengths and little or none of the blue end of the
• But an object painted red can only appear red if the light falling on it contains
sufficient red radiation, so that this can be reflected. Moreover, it will appear dark
when illuminated with a light source having no red radiation.
Mixing light of different colours
• When coloured light beams are mixed,
the result will always be brighter than the
colours, and if the right colours are mixed
in the right intensities, the result will be
• This is known as additive colour
mixing. The three basic light colours are
red, green and violet-blue.
• These are called the primary colours and
additive mixing of these colours will
produce all other light colours, including
Subtractive colour mixing:
• Subtractive colour mixing occurs for
example when coloured paints are
mixed on a palette.
yellow + magenta = red
yellow + cyan = green
magenta + cyan = violet-blue
yellow + magenta + cyan = black
CIE chromaticity diagram:
• A graphic representation of the range of
light colours visible to the human eye is
given by the CIE* chromaticity diagram.
• The saturated colours red, green and
violet are located at the corners of the
triangle with intermediate spectral colours
along the sloping sides, and magenta at
• Going inwards, they become lighter and
diluted at the same time.
• The centre of the triangle -where all
colours meet- is white.
• The colour values are numerically plotted
along the right-angled x- and y-axis.Thus,
each light colour can be defined by its xand y-values, which are called chromaticity
coordinates, or colour point.
•Although light sources may have the same colour appearance, this
doesn’t necessarily mean that coloured surfaces will look the same under
•Two lights that appear the same white, may be the result of different
blends of wavelengths.
•Colour rendering is an important aspect
of artificial lighting. In some situations
colours should be represented as
naturally as possible as under daylight
conditions, yet in other cases lighting
should highlight individual colours or
create a specific ambience.
•To classify light sources on their colour
properties the so called
colour rendering index (CRI or also
denoted as Ra) has been introduced.
•The light reflected from the rocking
horse enters the eye of the observer
forming in his brain an image as
depicted in the top right corner. In the
bottom picture the light falling on the
horse has no red radiation.
•This means that no light will
be reflected from the red parts of the
rocking horse and these parts will
appear dark to an observer as can be
•Both pictures indicate that the
spectrum of the light source plays an
important role in the way we perceive
the colour of objects.
•The general colour rendering index Ra,
derived from a set of eight test colours
taken from everyday live, is used to
evaluate the colour rendering
characteristics of a lamp. Its theoretical
•maximum value is 100.
•The lower the colour rendering index the
worse the colour rendering characteristics
of the lamp.
•For practical purposes the colour
rendering indices are divided into different
levels. DIN EN 12464-1 states six of these
•Described as the colour impression of a perfect black-body radiator at certain
•This concept can be best explained with the help of familiar thermal radiators like
the filament of an incandescent lamp or an iron bar.
•When these materials are heated to a temperature of 1000 K their colour
appearance will be red, at 2000-3000 K they will look yellow white, at 4000 K
neutral white, and at 5000-7000 K cool white. In other words: the higher the colour
temperature, the cooler the impression of the white light becomes.
Colour temperature is an important aspect in lighting applications – the choice of
colour temperature being determined by the following factors:
• Ambience: warm-white creates a cosy, inviting ambience; neutral/ cool-white
creates a business-like ambience.
• Climate: inhabitants of cooler geographical regions generally prefer a warmer
light, whilst inhabitants of (sub)-tropical areas prefer, in general, a cooler light.
• Level of illumination needed. Intuitively, we take daylight as a natural reference.
A warm-white light is daylight at the end of the day, at a lower lighting level. Coolwhite light is daylight during the middle part of day. This means that in
interior lighting, low illumination levels should be achieved with warm-white light.
When a very high lighting level is needed, this should be realised with a neutral or
cool white light.
• Colour scheme in an interior. Colours like red and orange are shown to
advantage with a warm-white light, cool colours like blue and green look somewhat
more saturated under a cool-white light.
All lamps with a most similar colour
temperature of over 5300 K belong to the
group of daylight white (tw) light sources,
like e.g. daylight white luorescent lamps.
High pressure mercury lamps and “white”
luorescent lamps belong to the group of
lamps with neutral white (nw) light colours
with colour temperatures between 3300 K
and 5300 K.
Incandescent lamps and “warm tint”
fluorescent lamps belong to the group
of lamps with warm white (ww) light colours
with a colour temperature under 3300 K.
One of the oldest electric lighting
Light is produced by passing a current
through a tungsten filament.
Least efficient – (4 to 24 lumens/watt).
Lamp life ~ 1,000 hours.
A type of incandescent lamp.
Encloses the tungsten filament in a
quartz capsule filled with halogen gas.
Halogen gas combines with the
vaporized tungsten and redeposits it
on the filament.
Lasts longer (up to 6,000 hrs.)
High Intensity Discharge (HID) Lamps:
produces light by means of an
electric arc between tungsten
electrodes housed inside a
translucent or transparent fused
quartz or fused alumina (ceramic)
arc tube filled with special gases.
Arc tube can be filled by various types of
gases and metal salts.
HID lamps are used in industrial high bay
applications, gymnasiums, outdoor lighting,
parking decks, street lights.
Efficient (up to 150 lumens/watt).
Long Life (up to 25,000 hours).
Drawback – take up to 15 minutes to come
up to full light after power outage.
Types of HIDs
Mercury Vapor (obsolete)
Arc tube contains argon,
mercury, and metal halides.
Gives better color temperature
Most common HID in use today.
Allow higher pressure &
Better efficiency, better CRI and
better lumen maintenance.
Pulse Start vs. older Probe Start
Ceramic vs. older Quartz arc tube
Most common commercial lighting
High Efficicacy: up to 100 lumens/watt.
Improvements made in the last 15 years.
T12: 1.5 inch in diameter.
T8: 1 inch in diameter.
~30% more efficient than T12.
T5: 5/8 inch in diameter.
~40% more efficient than T12.
Phosphor crystals Mercury atom
Linear (8 ft., 4 ft., 2 ft., 1 ft.)
Ubend (fit in a 2 ft. x 2 ft. fixture).
Circular (rare, obsolete).
Fixtures can be 4, 3, 2, or 1 lamp per
Standard Output (430 mA).
High Output (800 mA).
Very High Output (1,500 mA).
Compact Fluorescent Lamps (CFLs)
Fluorescent lamp that is small in size (~2
in. diameter, 3 to 5 in. in length).
Developed as replacement for
Two Main Types
Ballast non-integrated (allows only
lamp to be replaced).
•Excellent color available – comparable to
•Many choices (sizes, shapes, wattages,
•Wide Range of CRI and Color
•Energy Efficient (3.5 to 4 times
•Long Life (generally 10,000 hours –
lasts 12 times longer than standard 750
hour incandescent lamps)
•Less expensive dimming now available (010v dimming to 5%)
•Available for outdoor use with amalgam
Auxiliary component that performs 3
Provides higher starting voltage.
Provides operating voltage.
Limits operating current.
Old type ballasts were
New ballasts are electronic.
Lighter, less noisy, no lamp flicker,
•DEFINITION: The fraction of rated lamp lumens produced by a specific
•APPLICATIONS: High Ballast Factor
Typical Ballast Factor
Comparable light output in
Low Ballast Factor
Decreases light output
AND energy consumption
•For optimal efficiency lamps and ballasts must be properly matched.
•Maximize energy savings by selecting electronic ballasts with ballast
factor that provides target illuminance.
Ballast Circuit Types
Instant Start Ballast – starts lamp instantly with higher starting
voltage. Efficient but may shorten lamp life.
Rapid Start – delay of about 0.5 seconds to start; supplies starting
current to heat the filament prior to starting and continues during
operation. Uses 2 to 4 watts more than an instant start ballast.
Programmed Rapid Start - delay of about 0.5 seconds to start;
starting current heats the filament prior to starting, then cuts off
Light Emitting Diodes (LED):
Latest Lighting Technology.
Invented in 1962.
In the past, used as indicator lights,
automotive lights, and traffic lights; now
being introduced for indoor and outdoor
LED is a semiconductor technology.
Electroluminescence. Electrons recombine
with holes in the semiconductor, releasing
Lower energy consumption.
Longer lifetime (50,000 to 100,000 hrs).
Greater durability and reliability.
Comparison of LED with a Fluorescent Lamp:
Popular T8 Brand
Life Expectancy 12 hrs per
start / 3 hrs per start
10 years 10
20000 hours 16000
Light output at 0° C
Watt Rating, typical B.F. = 0.8