This presentation explains how to improve energy efficiency in lighting systems. It was prepared for energy auditor training in Nepal in the context of GIZ/NEEP programme. For further information go to EEC webpage: http://www.eec-fncci.org

1. Lighting
and
Energy Efficiency

2. Incandescent Lamps
• Incandescent lamps :
Light is produced by passing electric current through a thin fire
filament usually tungsten. Also known as GLS (General Lighting
Service).
• Reflector lamps :
Basically incandescent, with a high quality internal mirror, which
follows same parabolic shape of the lamp. Reflector is resistant to
corrosion, thus making the lamp maintenance free and efficient in
output.
• Halogen lamps:
Also called as tungsten-halogen lamp. Halogen lamps are high pressure
incandescent lamps containing halogen gases such as iodine or bromine
which allow the filaments to be operated at higher temperatures and
higher efficacies. At high-temperatures, chemical reaction involving
tungsten and the halogen gas recycles evaporated particles of tungsten
back onto the filament surface

3. • High-Intensity Discharge (HID) Lamp
A general term for mercury, metal halide and high-
pressure sodium lamps.
HID lamps contain compact arc tubes which enclose
various gases and metal salts operating at relatively
high pressures and temperatures.
Gas Discharge lamps

4. Gas Discharge lamps
Fluorescent Lamps (FTL)
Compact Fluorescent Lamps (CFL)
Mercury Vapor Lamps
Sodium Vapor Lamps
Metal Halide Lamps
Light is produced by excitation of gas
contained in either a tubular or elliptical outer
bulb

5. Fluorescent Lamps- A high efficiency lamp utilizing an electric
discharge through low pressure mercury vapor to produce
ultraviolet (UV) energy. The UV excites phosphor materials
applied as a thin layer on the inside of a glass tube which makes up
the structure of the lamp. The phosphors transform the UV to
visible light
High pressure sodium (HPS) - A high-intensity discharge lamp
type that uses sodium under high pressure as the primary light-
producing element.
Mercury vapor (MV) - A high-intensity discharge lamp type that
uses mercury and several halide additives as light-producing
elements.
Metal halide (MH) - A high-intensity discharge lamp type that
uses mercury and several halide additives as light-producing
elements.
Gas Discharge lamps

6. Luminaires
A complete lighting unit consisting of lamps and
the parts designed to distribute the light, to
position and protect the lamps, and to connect the
lamps to the power supply
Silvered glass, stainless steel, chromium plate
and vitreous enamel

7. Gear
• Ballast
– A device required by discharge lamps such as
fluorescent lamps to regulate voltage and current
supplied to the lamp during start and throughout
operation
– Energy loss is typically 10-20 % of total energy in
conventional ballast’s
• Igniters
– Used for starting high intensity Metal Halide and
Sodium vapour lamps

8. Illuminance
• Lumen (or Luminous flux) is a
measure of the total light output of
the lamp. A lamp's lumen output
rating expresses the total amount of
light the lamp emits in all
directions per unit time. Light
sources are labeled with an output
rating in lumens.
• Density of luminous flux incident
upon a surface. Illuminance is
measured in lux (lumens/square
meter).
• Lux (lx) is illuminance produced
by a luminous flux of one lumens
uniformly distributed over a
surface area of one square metre
Sunrise & Sunset : 500 lux,
Summer midday : 100000 lux
Winter midday : 10,000 lux,
Full Moon : 0.25 lux

9.
Lighting Terms
Circuit Watts is the total power in Watts drawn by lamps and ballast in
a lighting circuit
Luminous Efficacy is the ratio of light output to Watt input. Unit:
lumens per watt (lm/W)
Lamp Circuit Efficacy is amount of light (lumens) emitted by a lamp
for each watt of power consumed by the lamp circuit, i.e. including
control gear losses. This is a more meaningful measure for those lamps
that require control gear. Unit: lumens per circuit watt (lm/W)

10. Other Lighting Terms
Average maintained illuminance is average of lux levels
measured at various points in a defined area.
Color rendering index (CRI) is a measure of the degree
of color shift that objects undergo when illuminated by the
light source as compared with those same objects when
illuminated by a reference source of comparable correlated
color temperature.
In general, a lower CRI indicates that some colors may
appear unnatural when illuminated by a lamp.
Color rendering is measured on an index from 0-100, with
natural daylight equal to 100.

11. Energy savings options in
lighting System
• Make maximum use of natural light (North roof/translucent
sheets/more windows and openings)
• Switch off when not required
• Modify lighting layout to meet the needs
• Select light colors for interiors
• Provide lighting controls- timer switches / PV
controls/automation
• Provide lighting Transformer to operate at reduced voltage
• Install energy efficient lamps, luminaires and controls
• Clean North roof glass, translucent sheet and luminaries
regularly
• Adopt Task lighting