RE Technology Focus
LED LIGHTING
for Achieving Energy Efficiency
Energy efficiency is the buzzword today in
the broad areas of energy production and
consumption, where energy saved is energy
produced. Atanu Dasgupta says that with the
ongoing technological advancement in the field
of LED lighting in particular and government’s
patronage for achieving extra-ordinary energy
efficiency; tungsten incandescent lamps, fluorescent
tubes, and CFLs are destined to disappear soon.
Read on.
E
nergy efficiency has gradually
and truly become a very
important term at national
as well as at the global level.
Our goal is achieving maximum
energy efficiency with the use of
state-of-the-art technologies that
will reduce consumption of energy in
everyday life coupled with maximum
deployment of renewable energy,
so that the combined effect will
help cut down the dependence
on fossil fuel and reduce carbon
footprint. Basic generations of
electrical lighting systems include:
tungsten incandescent lamps,
fluorescent tubes, and CFLs. These
generations flourished together for
quite some time until the arrival of
LEDs. LED lighting is a technology of
extracting visible light energy from a
semiconductor p-n junction known as
light-emitting diode (LED).
Comparing Illumination
Technologies
Figure 1: Evolution of basic lighting technologies
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| Akshay Urja | December 2015
The key to energy efficiency in case
of lighting is lumens per watt that
is achievable practically. Through a
process of evolution over almost a
LED Lighting for Achieving Energy Efficiency
CONSIDERING LOWER
ENERGY COST OVER
A PERIOD OF TIME
CUMULATIVELY AND LESSER
MAINTENANCE COST AND
EXTENDED LIFE OF LED,
THE RATE OF RETURN ON
INVESTMENT IS VERY FAST.
century, various lighting technologies
have found favour with residential,
institutional, and industrial consumers.
Figure 1 shows why LED technology
is poised to score over all other
established technologies in terms of
efficacy or lumens per watt. However,
the cost of production for LED lights is
much higher today when compared to
other technologies. Considering lower
energy cost over a period of time
cumulatively and lesser maintenance
cost and extended life of LED, the rate
of return on investment is very fast.
The Technology of
LED Lighting
In case of LED technology, lightemitting diodes (LEDs) have replaced
conventional incandescent and
fluorescent lamps for general
lighting purposes. LEDs are also
being deployed nowadays for a
variety of applications, such as street
lighting, building lighting, automobile
lighting, and perhaps at every place
where conventional systems are
still operational and for a host of
new areas and unusual applications.
LED devices produce visible light
by means of electroluminescence,
a phenomenon in which electric
current, while passing through a
specially fabricated semiconductor
diode, causes the semiconductor
material to glow.
Traditionally, LEDs are being
used as indicator lamps in professional
and household electrical and
electronic devices. In fact, this
practice is likely to continue for a
longer period perhaps. As brighter
LEDs were developed, such devices
found applications in traffic lighting,
electronic billboards, and headlamps
for automobiles. Today, we find them
in flashlights, searchlights, cameras,
projectors, indoor and outdoor
lighting arrangements, institutional
and industrial lighting, special
purpose lighting and numerous
other applications.
Benefits of LEDs
As stated earlier, superior energy
conversion efficiency is the
principal advantage of LED lamps
Picture 1: A complete luminaire
over incandescent and fluorescent
lights and CFLs (Table 1). A typical
incandescent bulb, intended for home
use, converts about 10 per cent of the
supplied electrical energy into visible
light; the rest is wasted as infrared (IR)
radiation (‘heat’), which is invisible.
LED, in contrast, converts about
90 per cent of the supplied energy
into visible light, and only 10 per cent
goes into IR.
The other most significant
advantage of LED technology
lies in the long lifespans of LED
devices. A properly designed and
manufactured LED lamp lasts
about 35,000 to 50,000 hours,
which is more than 20 times the
average life of an incandescent bulb,
and about six times the life of a CFL.
Table 1: Comparison of LED lamps over incandescent and fluorescent lights and CFLs
Light Sources >>>
Incandescent Lamp
CFL
LED
Expected life (hours)
1,200
8,000
50,000
I/p power for similar lumen o/p
60
13–15
7
kWh consumed/1,000 hours
60
15
7
Colour rendition
Limited
Limited
Wide range
Dimmability
Yes
Restricted
Yes
Robustness
Sensitive
Sensitive
Breakable
Start time
Fast
Slow
Instant
Hazardous material
None
5 mg of Mercury per
lamp
None
Disposal
Landfill
Per guidelines
Per guidelines
Efficacy
620/60= ~10
620/15=~40
600/7= >85
Cost of ownership
Highest
Low
Lowest
December 2015 | Akshay Urja |
35
RE Technology Focus
THE OTHER MOST
SIGNIFICANT ADVANTAGE
OF LED TECHNOLOGY LIES
IN THE LONG LIFESPAN
OF LED DEVICES. A
PROPERLY DESIGNED
AND MANUFACTURED
LED LAMP LASTS ABOUT
35,000 TO 50,000 HOURS,
WHICH IS MORE THAN 20
TIMES THE AVERAGE LIFE
OF AN INCANDESCENT
BULB, AND ABOUT SIX
TIMES THE LIFE OF A CFL.
.
Thus, the long lifespan and energy
saving help reduce environmental
pollution and carbon footprint.
Apart from aspects, such as energy
savings, longer lifespan, and improved
quality of light that LED devices
offer, the easy controllability of such
deployment through intelligent
networking solutions can usher in a
paradigm shift in the way discoms and
municipalities are likely to utilize their
street lighting infrastructure in order
to deliver a cost-effective, sustainable,
and safer living space.
In the area of green initiatives
too, LED technology scores over
the conventional ones. LED lamps
are free from hazardous substances
(unlike CFLs) and they do not cause
shattering when dropped like their
predecessors. A typical LED lamp
can be designed and connected
as dimmable like an incandescent
bulb. Such an option, however, is not
available with fluorescent lamp or CFL.
This feature is useful for energy saving
and optimization of illumination and
energy cost. Optics in LED luminaire
(Picture 1) can be optimized effectively
for maximum benefit of the users
in terms of even distribution of light
and reduction of lumen losses in
undesired directions. This feature
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| Akshay Urja | December 2015
reduces light pollution and wastage
too. Further, LED lamps do not radiate
ultraviolet (UV) rays that can attract
insects and cause fading of wall
papers, artwork, clothing, etc., over a
period of time.
The LED lighting system offers
better natural colour rendering
characteristics that can help improve
safety and security in the areas where
it is deployed. With a high colour
rendering index (CRI), the LED device
makes it easier for all kinds of users
at homes, community buildings,
market places, or on streets. The easy
availability of cool, neutral, and warm
white LEDs have an additional option
of adjusting the colour temperature to
the specific lighting applications. It is
needless to say that with conventional
lighting technologies such alternatives
are unthinkable.
Although the illuminance (Lux/
watt) available from high pressure
sodium lamps (HPSL) compares
favourably with that of LED lamps,
the former produces undesirable hot
spots that can cause unavoidable
visibility, safety, and glare problems.
A typical LED device functions at
a lower temperature than a CFL.
The undesirable electromagnetic
interference (EMI) from the LED lamp
appears to be better controllable than
THE LED LIGHTING SYSTEM
OFFERS BETTER NATURAL
COLOUR RENDERING
CHARACTERISTICS THAT
CAN HELP IMPROVE SAFETY
AND SECURITY IN THE AREAS
WHERE IT IS DEPLOYED.
WITH A HIGH COLOUR
RENDERING INDEX (CRI), THE
LED DEVICE MAKES IT EASIER
FOR ALL KINDS OF USERS
AT HOMES, COMMUNITY
BUILDINGS, MARKET
PLACES, OR ON STREETS.
Figure 2: Cross-section of an SSL lamp
for household use
that from CFLs. The LED lamps are
also better poised in connection with
its vulnerability to electromagnetic
compatibility (EMC) issues. Figure 2
shows a cross-section of an SSL
lamp for household use.
In order to satisfy users’
preferences and actual needs,
the LED lamps can be manufactured
with colour shades ranging from
‘cool blue’ to ‘warm yellow’.
Presently, the principal
disadvantage of LED lamps is that
it costs considerably higher than
incandescent lamps and somewhat
more than CFLs. However, accounting
for the long lifespan that the LED
lamp offers and long-term cumulative
reduction in energy consumption and
accompanying reduction in carbon
footprint, consumers may actually
save money by using LED lamps in
majority of the situations. The other
disadvantage in connection with
outdoor installation of LED devices
(e.g., LED lamps for street lighting)
is its vulnerability to lightning strikes
and surges from the electrical
supply system and environment
that necessitates suitable protective
devices and efficient earthing system.
The encapsulation of LED lamps
for outdoor illumination needs high
degree of accuracy and workmanship
so that the luminaire is least
vulnerable to the environment.
LED Lighting for Achieving Energy Efficiency
Important Design
Parameters
There are a number of technical
aspects that need to be checked for
the LED luminaire design as a whole
with a lot of complex electronics
residing inside along with mechanical,
thermal, and photometric properties
including photo-biological factors,
built-in power factor correction
capabilities, and EMI/EMC issues.
The LED modules are most important
in respect of quality of luminescence.
The next is the design and choice
of the LED driver that needs careful
selection of electronic components—
both active and passive that include
a microprocessor plus switch
mode power supply (SMPS). The
performance of the driver, including
surge and transient protection
capabilities at various stages in the
driver contribute to effective long life
of the LED luminaire. Encapsulation
of the LED modules, driver board,
and other mechanical and thermal
management components like sizing
of the heat sink including choice
of material, heat sink compound
for thermal conduction, sealing of
the bottom metal collar with glass
insulator, etc., are very important
to offer a quality product as per
international standards. Figure 3
shows the construction of a typical
LED luminaire used at homes and also
the general internal disposition of a
driver. There is a strong possibility that
at the time of mass production, many
of the aforesaid factors are bypassed
or ignored for the sake of simplicity
and cost-cutting that demeans the
quality of the end product delivered.
The colour of LED lights, which is
known as Kelvin temperature (K), can
make it convenient to choose the right
type of lights that will render the right
effect one may desire. For example,
warm white light at 2,700°K~3,000°K,
produces calm, relaxing light that is
good for living rooms, dining rooms,
and restaurants. Natural white light at
4,000°K~4,500°K generates a friendly,
inviting light that is virtually good
for basements, garages, offices, and
other work places. Cool white light at
5,500°K~6,500°K, produces vibrant
light, which is ideal for display areas,
garages, and secured areas.
Harmful Effects of
Shortcuts during
Manufacture
In the event, substandard LED lamps
are allowed to flourish in the market,
the following detrimental effects will
have to be encountered:
ƒƒ The domestic lighting industry
will be severely restricted to grow
and multinational companies with
Figure 3: The construction of a typical LED luminaire used at homes
THERE ARE A NUMBER OF
TECHNICAL ASPECTS THAT
NEED TO BE CHECKED FOR
THE LED LUMINAIRE DESIGN
AS A WHOLE WITH A LOT
OF COMPLEX ELECTRONICS
RESIDING INSIDE ALONG
WITH MECHANICAL,
THERMAL, AND
PHOTOMETRIC PROPERTIES
INCLUDING PHOTOBIOLOGICAL FACTORS,
BUILT-IN POWER FACTOR
CORRECTION CAPABILITIES,
AND EMI/EMC ISSUES.
quality products will shy away. Thus,
the ‘Make in India’ concept will
suffer enormously.
ƒƒ Light emanating from cheap LED
lamps shall be of inferior quality
with unacceptable colour rendering
and photo-biological factors that
will affect public health adversely in
the long run.
ƒƒ Light output (lumens) from such
LED devices shall be low against
the electric power that they will
consume. But, an ordinary user
may take a long time to understand
such drawbacks and take
corrective actions.
ƒƒ The cheap LED fixtures, while
deployed in bulk, shall present
undesirable power factor to the
electrical grid and will result
in overheating of distribution
transformers—thus creating havoc
in the system and financial loss to
the suppliers. The consequential
cost of purification of the grid will
be enormous.
ƒƒ The life of such LED lamps shall
be much lower as compared to
properly standardized, designed,
and manufactured items that
EESL has been promoting under
government initiatives.
December 2015 | Akshay Urja |
37
RE Technology Focus
UNDER THE INITIATIVE
OF THE GOVERNMENT
OF INDIA, A NATIONAL
PROGRAMME FOR LEDBASED HOME AND STREET
LIGHTING WAS LAUNCHED
ON JANUARY 5, 2015
ACROSS THE COUNTRY. THE
OBJECTIVE OF THE PROJECT
IS INSTALLATION OF LED
BULBS FOR DOMESTIC
AND STREET-LIGHTING
IN 100 CITIES AND IS
TARGETED FOR COMPLETION
BY MARCH 2016.
.
Challenges of Mass
Scale Deployment
Adequate sensitization is necessary
for all stakeholders, which
includes manufacturers, users,
and implementers of LED lighting
projects—whether for home use,
outdoor, or industrial deployment. The
mechanical fittings, electrical wiring
and connections, and aesthetics
are pre-requisites for a long life and
trouble-free LED lighting system.
Since surge suppression is sacrosanct,
particularly for outdoor installation
such as street lighting, adequate
surge arresters must be provided as
an integral part of LED luminaires.
In the event, surge arresters are not
installed, the life of the SSL lamps
are bound to reduce and then the
benefits of long-term saving in
maintenance will be lost while the
higher cost of implementation cannot
be compensated quickly as return of
investment will take a longer time. The
surge arresters will essentially require
a good grounding system so that
the energy associated with incoming
surges due to lightning and electrical
distribution system faults can be
grounded effectively and immediately
after occurrence. The electromagnetic
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| Akshay Urja | December 2015
interference (EMI) from LED lighting
system is also needed to be quenched
at the source itself as per international
standards. Otherwise, this may create
unwanted interference in the radio
frequency spectrum and may cause
maloperation in systems that use
radio frequencies, e.g., broadcast
receivers, Wi-Fi based data acquisition,
monitoring and control systems,
electro-medical equipment, and many
others. In order to control the EMI
caused by the pervasive LED systems
in near future, it requires proper
design considerations in the driver
circuit and also an effective
grounding system.
Indian Initiative
Under the initiative of the Government
of India, a National Programme for
LED-based Home and Street Lighting
was launched on January 5, 2015
across the country. The objective of
the project is installation of LED bulbs
for domestic and street-lighting in 100
cities and is targeted for completion
by March 2016. This programme is
expected to result in conservation
of nearly 8 billion units of electrical
energy every year leading to a saving
of N 4,000 crore. Subsequently, EESL
(a public sector undertaking) has
been mandated to replace existing
street lights at various urban local
bodies (ULBs), throughout the length
and breadth of the country, with
energy efficient LED luminaire along
with associated monitoring and
control system and other essential
accessories.
PTC India Ltd (a joint sector
company in the power sector) has
been actively involved in the initiatives
related to implementation of energy
efficiency in the industry as well
as in the domestic sector. In this
connection, the role of PTC India Ltd
in demand side management-based
LED lighting projects (DELP) and LEDbased luminaire for street lighting have
been well accepted in the country.
This way, the proliferation of LED
lighting with all incidental advantages
of in-built energy efficiency, lumen
efficacy, long life-cycle, precise
control and management of the
lighting system, etc., have been
instrumental in ushering a new vista of
opportunities for all the stakeholders
and is expected to pave the way for a
smart and holistic development of the
entire society.
Future Trend
Next-generation LED lighting system
is expected to deliver unprecedented
power savings and product reliability
and they will probably be deployed in
such areas that is unimaginable today.
New possibilities in the field of lighting
design covering super-efficient LED
technology coupled with state-ofthe-art control engineering are going
to open up new vistas—whether
at home, in industry or supporting
myriad forms of activities in daily life.
Organic light-emitting diodes (OLEDs)
have already been ushered in as the
future generation of lighting, which
produce light over larger areas and
can be produced, assembled, and
integrated in any form of structure
and pattern as per users’ choice. Such
innovations are aimed not merely to
demonstrate the technical expertise
of the designers but also to offer users
substantial value addition on account
of their flexibility in a variety of
applications while using much smaller
amount of input power.
Future applications of LED
lighting system shall be optimized
for production of artificial light for
NEXT-GENERATION LED
LIGHTING SYSTEM IS
EXPECTED TO DELIVER
UNPRECEDENTED POWER
SAVINGS AND PRODUCT
RELIABILITY AND THEY WILL
PROBABLY BE DEPLOYED
IN SUCH AREAS WHICH IS
UNIMAGINABLE TODAY.
.
LED Lighting for Achieving Energy Efficiency
SOME OF THE BROAD
AREAS WHERE LED SYSTEM
IS GOING TO MARK ITS
POWERFUL PRESENCE
INCLUDE FOOD PROCESSING
INDUSTRY, PRINTING
PROCESSES, LED DRYING
FOR INDUSTRIAL AND
DOMESTIC USAGE, ETC.
.
nurturing plant growth at a healthy
pace. The dedicated system for
agriculture will offer low power,
high-efficiency, uniform light pattern,
homogenous light distribution at
precise wavelengths and colour
ratios that are needed for superior
photosynthesis process. LED devices
are all set to be used for waterpurification purposes for providing
safe drinking water for human
consumption, medical devices, and
all other areas where water is used
with various limits of purity and
minerals. For this purpose, specially
designed LEDs shall be used in
water-treatment plants, shunning the
deployment of chemicals or mercurybased UV lamps. Some of the broad
areas where LED system is going to
mark its powerful presence include
food processing industry, printing
processes, LED drying for industrial
and domestic usage, etc.
In the future, LED devices
can be used to power wireless
communication networks as well,
using the so-called Li-Fi (Light
Fidelity) technology that will use light
instead of radio waves for handling
data traffic. It is also understood that
the future will be full of lasers.
Laser diodes, which are already being
used as car headlights, are expected
to gradually replace LEDs and will
dominate the lighting industry for its
improved efficacy. Laser diodes can
also be used for ‘intelligent lighting’
like smartphone-controlled projectors
that display imagery or data on walls
or floors. It is predicted that laser
diodes will be used extensively for
wireless communications. In future,
laser-based Li-Fi may replace LEDbased Li-Fi, as a laser diode-based
version would be faster than LEDbased Li-Fi.
The future trend in the LED lighting
industry will also introduce the
concept of human-centric lighting.
In this connection, a new study
published by LightingEurope, AT
Kearney, and the German Electrical
and Electronic Manufacturers’
Association (ZVEI) states that humancentric lighting will add additional
value because of the introduction of
newer applications created for LED
lighting, such as treatment of diseases
or skin conditions, the improvement
of productivity and concentration, as
well as controlling sleeping disorders,
where colour temperature of ambient
light can provide a better sleep at
night. The study predicts that the
industrial segment will be the most
significant beneficiary from humancentric lighting. These benefits will
lead to increase in productivity and
market opportunity impacting the
society in a manner hitherto unknown.
Conclusion
When buying an LED lamp, one will
hear the term ‘lumens per watt’,
that quantifies luminous efficacy.
The higher the lumens per watt, the
better the LED lamp, as it consumes
lesser energy to emit the same,
or a greater amount of light. The
luminous efficacy of LEDs range from
80 Lm/W to 160 Lm/W. The energy
efficiency, thus achieved, makes
it cost-effective and it amounts to
less money spent on electricity bills.
While buying, prospective LED users
should also ask about the correlated
colour temperature (CCT) of a lamp or
fixture. The buyer must recognize that
all lamps having same CCT may not
appear to be the same. Therefore, it is
recommended to not encourage an
assortment of manufacturers unless
products of various manufacturers
have been tested with each other for
reasonable compatibility.
Modern LED lamps have high
luminous efficacy along with long life
expectancy of up to 50,000 hours,
which makes it truly energy-efficient.
The savings accrued from the reduced
power consumption combined with
the lower maintenance costs make
LEDs a smart investment. However,
the life of the LED luminaire is truly
a function of the efficient driver and
protection system it is provided with
rather than the LED modules in it.
So, it is the lifetime of the electronics
associated with the LED luminaire that
really matters at the end of the day.
Mr Atanu Dasgupta is a Consultant,
PTC India Ltd, New Delhi, India.
Email: atanu.dasgupta@ptcindia.com.
December 2015 | Akshay Urja |
39