Lighting architecture notes lecture

1. LIGHT SOURCE
•Electric energy is converted to light energy where heat is the side
effect.
1. Incandescent lamps: general incandescent bulbs.
• Most commonly used
• Least expensive
• Their soft, warm glow is reminiscent
of candle light.
• Least efficient lighting source –
approx. 90% of the electricity goes
into heat generation rather than light
production.

2. INCANDESCENT BULB •Bulbs convert power into light
by passing electric current
through a filament of tungsten
wire. The wire consists of
minicoils.
•The current heats the
tungsten filament until it
glows.
•The glass bulbs are filled with
an inert gas mixture primarily
of argon and nitrogen.
•The bulb can be clear, diffuse,
tinted or coloured.
•It gives out attractive warm
yellow light.
•Also called GLS – General Lighting Service Lamp – used for domestic
purpose.
•Standard incandescent lamps last about 750 – 1000 hours.

3. ADVANTAGES & DISADVANTAGES OF INCANDESCENT LAMPS
INCANDESCENT & HALOGEN LAMP
•Start & warm up almost instantly & can be extinguished & restarted at
will.
•Ordinary incandescent lamps – 5 to 20 Lumens / Watt
•Halogen lamps – 15 to25 Lumens / Watt
Advantage Disadvantage
Low initial cost High operating cost
Creates inviting environment Fragile
Immediate starting Short life
Easily dimmed Low lumen per watt
Variety of shapes, sizes, and applications High heat output
Easy to install

4. HALOGEN BULB (tungsten-halogen lamp)
•Slightly different shape & thicker heavier
glass bulb.
• An incandescent lamp with a tungsten
filament contained within an inert gas and
a small amount of a halogen such as
iodine or bromine.
•In ordinary incandescent bulb the
filament evaporates over time & bulb wall
blackens slowly as tungsten is deposited
on it.
•The combination of the halogen gas and
the tungsten filament produces a chemical
reaction known as a halogen cycle which
increases the lifetime of the filament and
prevents darkening of the bulb by
redepositing tungsten from the inside of
the bulb back onto the filament.
•Lamp life ranges from 2000 hours
to 10,000 hours.
•Whiter & brighter throughout its
life.

5. LOW VOLTAGE HALOGEN LAMPS
•Low voltage & smaller - throws bright light on a precise spot – highly
focused light.
•Comes with an inbuilt transformer that reduces the voltage from 220
volt to 12 volt.
•Halogen low voltage lamps are available in a variety of voltages and
strengths. Voltages extend from 6V to 50V, while the performance levels
lie between 10W and 590W.
•Tungsten halogen low voltage lamps are used today in many
applications. Originally developed for photography, they have now won
a place in traffic and signaling systems and in general indoor and
outdoor lighting system.

6. LOW VOLTAGE HALOGEN LAMPS
•Compact but effective.
•Provides upto 50% more light than conventional voltage halogen
system using same amount of energy.
•Used for – accent or display lighting / suspended down light or
track-lights generally used in retail & commercial areas / domestic
areas.
Halogen: a series of non-metal elements, comprising fluorine (F), chlorine (Cl), bromine
(Br), iodine (I), astatine (At). The group of halogens is the only periodic table group which
contains elements in all three familiar states of matter (e.g., solid, liquid & gas) at standard
temperature and pressure.

7. MOST COMMON APPLICATIONS
Ordinary incandescent lamps are used in – residences, hotels &
motels & some retail environment where residence like quality is
desired.
Halogen lamps – residential down lights, outdoor lighting, hotels,
motels, retail display in recessed lighting, track lighting & other lamp
holders in stores of all kinds.
Low voltage halogen lamps – used in museums, galleries, residences,
landscape lighting, special effects like cove lighting and illumination
inside and under cabinets.

8. FLUORESCENT LAMPS
• Introduction in 1938
•Aesthetically they are second class – unpopular with interior designer
•Widely used because they are more efficient than incandescent lamps.
Glass tubes coated on interiors with phosphor – a chemical compound
that emits light when activated by ultraviolet energy.
Air in the tube is replaced with argon gas & a small amount of
mercury is added.
When f. lamp is turned on, the electricity heats cathodes at each end
causing them to emit electrons, which in turn create an electric arc
between the cathodes. The electrons in this arc collide with mercury
vapour & argon or other gas atoms to produce invisible ultraviolet rays.
These rays excite the fluorescent phosphor coating, producing visible
light.
Fluorescents are highly efficient because 80% of their light comes
from the phosphor coating.

9. BASIC COMPONENTS OF A FLUORESCENT LAMP
• BULB: usually a straight glass tube - can be circular, U-shaped,
or curved .
•PHOSPHOR: coating inside the bulb that transforms ultraviolet
radiation into visible light. The colour of the light produced depends
upon the composition of phosphor.
•BASE: used to connect the lamp to the circuit & support it in the
fixture.
•CATHODE: located at each end of the lamp. Cathodes are coated
with a material that emits electrons & usually are made of coiled coil or
single coil tungsten wire.
•GAS: argon or a mixture of inert gas at low pressure – krypton
sometimes is used.
•MERCURY: a minute quantity of liquid mercury is placed in the bulb
to furnish mercury vapour.

10. BASIC COMPONENTS OF A FLUORESCENT LAMPS

11. COMPACT FLUORESCENT LAMP
•It is a fluorescent lamp designed to replace an
incandescent lamp.
• Some types fit into light fixtures formerly used
for incandescent lamps.
•The lamps use a tube which is curved or folded
to fit into the space of an incandescent bulb.
•FL & CFL – provides good energy
efficiency.
•FL & CFL can used in many places –
homes, businesses etc.
•Smaller in size
•Different shapes – folded, spiral,
circular.
•Available in 9 watt to 26 watt.
•It saves 75% of energy
•Generally used for commercial lights

12. LAMP LIFE & EFFICIENCY
•Fluorescent lamps 4/5 times more efficient.
•40 watt incandescent lamp produces 445 lumens.
40 watt fluorescent lamp produces 3050 lumens
•40 watt incandescent lamp – 1500 hours
40 watt fluorescent lamp – 20,000 hours
BRIGHTNESS
23 WATT = 100 WATT
LAMPLIFE
10,000 HOURS 750 HOURS
POWER CONSUMPTION
25% 100%
EFFICACY COMPARISION
Compact fluorescent bulbs are
more efficient than
incandescent bulbs in
brightness, power
consumption & lamp life.
BULB REPLACEMENT COST
One 23 watt CFL lasts as long
as 18 incandescent bulbs –
thereby saving the cost of
replacing those bulbs.

13. HID LAMPS (HIGH-INTENSITY DISCHARGE )
•Designed to emit a great deal of light from a compact, long-life
light source.
•Most often used for street, parking lot lighting & for large indoor
spaces like gymnasiums & industrial work force.
•Energy efficient – producing 50 to 100 lumen per watt.
TYPES OF HID LAMPS:
Metal Halide Lamps
Sodium Lamps
Mercury Vapour Lamps

14. METAL HALIDE LAMP
•Produce white light .
•Available in many sizes – compact
lamps used in track lighting & table
lamps to huge lamps for lighting
stadiums.
•Colour of light slightly greenish –
used where colour is not critical -
e.g., sports arenas, parking lots,
landscape lighting & building
floodlights.
The color rendering index (CRI) is a quantitative
measure of the ability of a light source to
reproduce the colors of various objects faithfully
in comparison with an ideal or natural light
source. Light sources with a high CRI are
desirable in color-critical applications such as
photography and cinematography.

15. SODIUM LAMP
•Two types:
High pressure sodium lamp (HPS)
 Low pressure sodium lamp (LPS)
•HPS works on principle of ionizing of
sodium vapours – provides more light
than any other lamp – offer very high
lumens/watt – yellow colour used on
bridges, railway lines, tunnels, road
lighting, parking lots, heavy industrial
work places, ware housing, security
lighting – where light colour is not so
important.
•LPS are even higher in lumens/watt –
but colour is so poor that their use is
limited to security lighting.

16. MERCURY VAPOUR LAMP
•Older type of lamp that remains in common use as streetlights &
security lights.
•Compare to other HID lamps MVL have relatively poor colour &
low energy efficiency – almost never used in new construction.
•It has a white light.
•Used on bridges, railway lines & bridges – but not in factories
because it has a tendency to flicker (an inconstant or wavering
light).
•Also known as flood light.