artficial lighting

8/17/2019 Artficial Lighting

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Energy Efficient ArtificialLighting

EE 3202

Individual Project

Name : S.P.M. Sudasinghe

Index No : 100!"#

$ield : Electrical Engineering


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CONTENTS

Page

1. Introduction 1

!. Light

Measurements of Light "

". Lighting %echnologies Incandescent Lam&

%ungsten 'alogen Lam&

$luorescent %u(es

)$L

'igh Intensity *ischarge Lam&s

LE* Lam&s

Im&ro+ing %echnologies

,

-

/

/

,. Strategies for energy efficient lighting

*efine light reuirements

)hoose efficient light source Select (est light fitting

Lighting Maintenance

Maximum use of day light

Lighting )ontrol

2ther methods to im&ro+e efficiency

1011

1!

1!

1"

1,

. )onclusions 1,

-. 3eferences 1

1. INTRODUCTION

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Pro+iding light (y means other than the sun is called Artificial Lighting. In early days &eo&le use artificial

lighting to get the sight 4hen there is no sun light5 (ut today it is used not only for get the sight (ut also for

Aesthetic &ur&oses. $rom around 0000 6) &eo&le use fire to get light. 3omans &roduce the first candle 4ith

4ic7 and gas lighting 4as common in 1 th century. As time &asses the era of electric lighting (egan. %he first

electric lam& 4as the arc lam& in 4hich an electric current 4as made to 8um& across t4o car(on electrodes.

After that Sir 9ose&h S4ann of England and %homas Edison (oth in+ented the first electric incandescent lam&s

during the 1/0s. After that +arious electric lighting technologies 4ere introduced to the 4orld. Peo&le concern

+ery much on the efficient lighting technologies in the &ast fe4 decades.

Estimates indicate that energy consum&tion (y lighting is

a(out 1 "0; of a commercial (uilding


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2(8ecti+es:

• >se energy efficiently for lighting &ur&oses in *omestic sector

• 3educe energy 4astage from electric lighting in domestic consumers

• Sa+e on electricity (ill and sa+e on demand

Methodology:

In the +ery (eginning of the &ro8ect5 the scientific literature rele+ant to the &ro8ect such as the (asics of

Illumination Engineering and &hotometry are studied. After that the study is a(out the lighting technologies in

the 4ord5 and a(out their ad+antages5 disad+antages and suita(ility for the domestic lighting &ur&oses.

Incandescent5 $luorescent and LE*s are the common lighting technologies used in the domestic usage. %y&ical

data a(out these technologies such as cost5 efficacy and life time are collected from trusted sources and from the

local mar7et. %hen a com&arison of these technologies is carried out to select an efficient one through them

(ased on the cost effecti+eness.

Selecting an efficient light source is not enough to increase the efficiency of a lighting system. It is essential to

minimi?e the energy 4astage and use the energy 4ith maximum efficiency as &ossi(le. So the 4ays of energy

4astage in the domestic lighting system is find out and also the solutions to minimi?e them.

Some of these solutions can (e a&&lied at the designing and construction &rocess of the (uilding such as the

4ays to maximi?e the use of natural day light. %here are many architectural solutions to maximi?e the use of

natural day light 4ithout increasing the load on the air conditioning system and 4ithout sacrificing the comfort

of the residents. And then the study is a(out the methods of im&ro+ing the efficiency of the (uilding after the

construction &rocess such as maintenance of a lighting system and adding automatic controllers.

2. LI!T

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@isi(le Light is electromagnetic radiation that is +isi(le to the human eye5 and is res&onsi(le for the sense of

sight. @isi(le light has a 4a+e length in the range of a(out "/0 ,0 nm (et4een the in+isi(le infrared5 4ith

longer 4a+e lengths and the in+isi(le ultra+iolet 4ith shorter 4a+e length

"ea#ure$ent# o% Li&'t

Light has an intensity that is determined (y the am&litude of the radiation and determines the &erce&tion of the

(rightness of the light. It also has a 4a+e length or freuency that determines the colour. Light may include a

range of different freuencies or colour.

%he sensiti+ity of the human +isual system is not the same at all 4a+elengths in the range "/0 nm to /0 nm.%his ma7es it im&ossi(le to ado&t the radiometric uantities con+entionally used to measure the characteristics

of the electromagnetic s&ectrum for uantifying light. 'ence another t4o systems ha+e introduced to measure

light.

aB Photometry System

In this system light uantities are measured 4ith 4a+e length 4eighted 4ith res&ect to a standardi?ed

model of human (rightness &erce&tion. %he )ommission Internationale de l


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LightingTechnologies

Incandescence

Incandescent

Tungsten

Halogen

Gas Discharge

Fluorescent

HID

Solid State

LED OLED

)olor 3endering Index : %he a(ility of a light source to render colors of surfaces accurately can (e con+eniently

uantified (y the colorrendering index. If )3I is close to 100 then the source renders true colours 4ell.

As im&ortant as the uantity or (rightness of light is the uantity. %he three main &ro(lems that com&romise the

uality of light are

i. lare : %he &resence of a luminance much a(o+e the a+erage fore the +isual field 4ill &roduce

discomfort and is called glare.

ii. ,eilin& Re%lection# : @eiling reflections are caused (y (right light sources reflected from a tas7

surface5 such as a (oo7.

iii. E)ce##ive -ri&'tne## Ratio : It occurs 4hen there are surfaces 4ithin the same s&ace 4ith largedifferences in (rightness

3. LI!TIN TEC!NOLOIES

3.1 Incande#cent La$+

In incandescent lam&5 4hich is also called #eneral Lighting Ser+ice Lam& C#LSB5 light is &roduced4ith a %ungsten filament Cmelting &oint "-HB heated to a high tem&erature (y an electric current

through it. %he (ul( is filled 4ith an inert gas such as argon C";B and nitrogen C;B to reduce e+a&oration of the filament and &re+ent its oxidation at a &ressure of a(out 0 7Pa C0. atmB. %he filament is coiled to reduce

heat con+ection to the filling gas. %he (ul( is generally made of a soft soda glass and its si?e is set so that it

does not get too hot and the tungsten that e+a&orates from the filament during the life of the lam& does not

(lac7en the (ul( too much. An electric current heats the filament to ty&ically !5000 to "5"00 H. %hese lam&s can

o&erate (oth from *) or Ac current. Incandescent (ul(s ha+e a continuous s&ectrum radiating more energy at

long 4a+e lengths C3edB5 and excellent colour rendering index a(out 100. 2nly 10; of the electrical energy

in&ut is con+erted to +isi(le light and other 0; of energy emits as heat. *ue to the &oor efficiency of

incandescent (ul(s many go+ernments ha+e introduced measures to (an their use. Incandescent (ul(s are

manufactured in a 4ide range of si?es5 light out&ut5 and +oltage ratings5 from 1. +olts to a(out "00 +olts. %heyreuire no external regulating eui&ment and ha+e lo4 manufacturing costs. As a result5 the incandescent lam&

4ere 4idely used in household and commercial lighting5 for &orta(le lighting such as ta(le lam&s5

car headlam&s5 and flashlights5 and for decorati+e and ad+ertising lighting. In (uildings 4here air

conditioning is used5 incandescent lam&s heat out&ut increases load on the air conditioning system.

%y&ical Pro&erties of Incandescent (ul(s:

• Efficacy 1 lm= C1! lm=B

• Life 1000 hours

• )3I 100

• ))% !00H!00HC=armB

• *imming easily dimma(le

4

Figure ': Spectral distribution of t$e output of


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Ad+antages

• Inex&ensi+e

• Easy to use5 small and does not need auxiliary

eui&ment

• Easy to dim (y changing the +oltage

• Excellent color rendering &ro&erties

• *irectly 4or7 at &o4er su&&lies 4ith fixed +oltage

• $ree of toxic com&onents

Instant s4itching

*isad+antages

• Short lam& life C1000 hB

• Lo4 luminous efficacy

• 'eat generation is high

• Lam& life and other characteristics are

strongly de&endent on the su&&ly +oltage

• %he total costs are high due to high o&eration

costs.

3.2 Tunten !alo&en La$+

%ungsten halogen lam&s are deri+ed from incandescent lam&s. Inside the (ul(5 halogen gas in high &ressure

limits the e+a&oration of the filament5 and rede&osits the e+a&orated tungsten (ac7 to the filament through the so

called halogen cycle

'alogen )ycle:

• %he 'alogen com(ining 4ith the %ungsten +a&or on the 4all of the lam& at a(out !00)

• %he %ungsten 'alide +a&or reach close to the filament in extremely high tem&erature

• It s&lits into %ungsten and 'alogen again and %ungsten de&osited on filament

)om&ared to incandescent lam& the o&erating tem&erature is higher5 and conseuently the color

tem&erature is also higher5 4hich means that the light is 4hiter. )olor rendering index is close to 100

as 4ith incandescent lam&s. *ue to the higher tem&erature (ul( must (e made from uart? or high

melting &oint glass. %hese (ul(s are more ex&ensi+e as it is hard to ma7e the uart? outer (ul( and it is harder to introduce the gas fill into the lam& due to the high filling &ressure.

'alogen lam&s ha+e continuous s&ectrum that emits >@5 +isi(le light C1!;B and infrared radiation and (ul(s are

do&ed or coated to filter out the >@ radiation. %he latest &rogress in halogen lam&s has (een reached (y

introducing selecti+eI3mirrorcoatings in the (ul(. %he infrared coating redirects infrared radiations

(ac7 to the filament. %his increases the luminous efficacy (y ,0-0; com&ared to other designs andlam& life is u& to ,000 hours.

%here are halogen lam&s a+aila(le for mains +oltages or lo4 +oltages C-!,@B. %he small si?e of halogenlam&s &ermits their use in com&act o&tical systems for &ro8ectors. Also they are used for light source of

Automo(ile head lights and some manufacturers &roduce them for household fittings to re&lace standard

incandescent (ul(s. S&ecial &recautions are reuired to a+oid from firing and (urning ha?ards due to high

tem&erature.

%y&ical features:

• Efficacy 1"Lm= C1/ lm=B

• Life !000 ,000 hours

• )3I 100

• ))% !/00H "!00H C=armB

• *imming easy

Ad+antages

• Small si?e

• *irectional light 4ith some models Cnarro4

(eamsB

• Lo4+oltage alternati+es

• Easy to dim

•Instant s4itching and full light out&ut

• excellent color rendering &ro&erties

*isad+antages

• 'igh surface tem&erature

• Lam& life and other characteristics are

strongly de&endent on the su&&ly +oltage

• Ex&ensi+e than incandescent

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3.3 (luore#cent Tue

$luorescent lam&s are the most commonly used form of discharge lam&. %hey come in a +ariety of sha&es and

si?es and are a+aila(le in a 4ide range of colours. %he original form of the lam& 4as a long straight tu(e.

$luorescent lam&s 4or7 (y generating ultra+iolet radiation in a discharge in lo4 &ressure mercury +a&or. %his is

then con+erted into +isi(le light (y a &hos&hor coating on the inside of the tu(e. %he electric current su&&lied to

the discharge has to (e limited (y control gear to maintain sta(le o&eration of the lam& (ecause they dis&lay

negati+e +oltagecurrent characteristics. %raditionally this is done 4ith magnetic (allast (ut most circuits

no4 use high freuency electronic control gear .

%he tu(e is made from a glass 4ith high iron content to a(sor(

the >@ radiation. Phos&hor coating is a&&lied inside the (ul(.

%here is 4ide +ariety of &hos&hors a+aila(le each &roduces

different s&ectrum of light. %u(e is filled 4ith no(le gas.

Linear lam&s come in +ariety of diameters and lengths. In diameter

%1! C1!1/ inchB5 %/ C/ 1/ inchB and % C 1/ inchB. % lam&s

&erform (est at the am(ient tem&erature of "O)5 and %/ lam&s

at !O). %he % has a +ery good luminous efficacy C100 lm=B5the same lam& surface luminance for different lam& &o4ers

Csome lam&sB5 and o&timal o&erating &oint at higher am(ient

tem&erature. % lam&s are shorter than the corres&ondent %/

lam&s5 and they need electronic (allasts.

)orrelated color tem&eratures C))%B +ary from !00 H C4arm 4hiteB and -00 H CdaylightB u& to

1 000 H and color rendering indices C)3IB from 0 to are a+aila(le. 6ecause they contain

mercury5 many fluorescent lam&s are classified as ha?ardous 4aste. %he >nited States En+ironmental Protection

Agency recommends that fluorescent lam&s (e segregated from general 4aste for recycling or safe dis&osal

%y&ical $eatures• Luminous Efficacy : 0100 lm=

• ))% : !00 -00H

• )3I : 0

• Lam& Life : 100001-000 hours

Ad+antages

• Inex&ensi+e C than )$L and LE*B

• #ood luminous efficacy

• Long lam& life5 10 000 1- 000 h• Large +ariety of ))% and )3I

*isad+antages

• Am(ient tem&erature affects the s4itchon

and light out&ut

• Need of auxiliary (allast and starter orelectronic (allast

• Light out&ut de&reciates 4ith age

• )ontain mercury

Short (urning cycles shorten lam& life

6allast

6allast is a current limiting de+ice5 to counter negati+e resistance characteristics of any discharge lam&s. Incase of fluorescent lam&s5 it aids the initial +oltage (uildu&5 reuired for starting. %here are t4o ty&es of

(allasts called Magnetic (allast Ccho7eB and Electronic (allasts.

"a&netic alla#t is (asically an inductor. It limits the current Cslo4 do4n the increasing of currentB and

the +oltage s&i7e is &roduced 4hen current through the inductor is ra&idly interru&ted C is used in some circuitsto first stri7e the arc in the lam&B. $or large lam&s5 line +oltage may not (e sufficient to start the lam&5 so

an autotransformer 4inding is included in the (allast to ste& u& the +oltage. $or magnetic (allasts5 ca&acitor

must (e connected in &arallel for &o4er factor correction. %hey o&erate at the 0 or -0'? freuency of the A)

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+oltage. %his means that each lam& s4itches on and off 100 or 1!0 times &er second5 resulting in a &ossi(ly

&erce&ti(le flic7er and a noticea(le hum.

Electronic alla#t alters A) +oltage freuency C0 '?B into highfreuency A) C! 0 7'?B 4hile alsoregulating the current flo4 in the lam&. Some still use an inductance to limit the current5 (ut the higher

freuency allo4s a much smaller inductance to (e used. 'igh freuency o&eration reduces the (allast losses and

also ma7es the discharge itself more effecti+e. 2ther ad+antages of the electronic (allasts are that the light is

flic7erfree and there is the o&&ortunity of using dimming de+ices.

$luorescent lam& (allasts differ from the starting method of the lam&. %hey are• Pre'eat #tartin& Cs4itch startB: It is an old method used to start the fluorescent tu(es using a

starter s4itch and (allast Ccho7e coilB. Starter &asses the current through it at starting and filaments

heat u& in that &eriod. After some time starter interru&t the connection through it and hence +oltage

&ulse generated (y the cho7e coil.

• Ra+id Start: the lam&s (allast constantly channels current through (oth electrodes. %his

current flo4 is configured so that there is a charge difference (et4een the t4o electrodes5

esta(lishing a +oltage across the tu(e. Less +oltage is reuired for starting than 4ith instant

start lam&s5 thus using smaller5 more efficient (allasts

• In#tant Start: sim&ly use a high enough +oltage to (rea7 do4n the gas and mercury column

and there(y start arc conduction.

3./ Co$+act (luore#cent La$+ C(L

%he )$L is a com&act +ariant of the fluorescent lam&. %he o+erall length is shortened and the tu(ular discharge

tu(e is often folded into t4o to six fingers or a s&iral. $or a direct re&lacement of tungsten filament lam&s5

such com&act lam&s are eui&&ed 4ith internal (allasts and scre4 or (ayonet ca&s CIntegrated )$LB.

%here are also &in (ase )$Ls5 4hich need an external (allast and starter for o&eration CNonIntegrated )$LB.

In general com&act fluorescent lam&s are less efficient than linear lam&s. Integrated )$Ls are easy to install and

the ad+antage of &in (ase lam&s CNonintegratedB is that it is &ossi(le to re&lace the (urnt lam& 4hile 7ee&ing

the (allast in &lace. )$Ls turn on 4ithin a second5 (ut many still ta7e time to achie+e full (rightness. )$Ls, li7e

all fluorescent lam&s5 contain mercury as +a&or inside the glass tu(ing. Most )$Ls contain " mg &er (ul(5

4ith the (ul(s la(eled JecofriendlyJ containing as little as 1 mg. 'ealth and en+ironmental concerns a(out

mercury ha+e &rom&ted many 8urisdictions to reuire s&ent lam&s to (e &ro&erly dis&osed of or recycled5 rather

than (eing included in the general 4aste stream sent to landfills. Safe dis&osal reuires storing the (ul(s

un(ro7en until they can (e &rocessed.

%y&ical features

• Luminous Efficacy 00 lm=

• Life 000h 1000h

•

)3I /0

• ))% !00H -00H

• *imming &ossi(le for some ty&es only

•

3un u& time a(out -0s C for full (rightnessB•

• Ad+antages

• #ood luminous efficacy

• Long lam& life C-0001! 000 hB

• %he reduced cooling loads 4hen

re&lacing incandescent lam&s

• Easy to install

•

• *isad+antages

• Ex&ensi+e

• Not dimma(le Ca&art from s&ecial modelsB

• Light out&ut de&reciates 4ith age

• Short (urning cycles shorten lam& life

• )ontain mercury

• =hen tu(e (urns out 4hole lam& is useless

•

•

3./ !i&' Inten#it* Di#c'ar&e La$+#

•

• %he family of architectural light sources 4ith the highest light out&ut le+els is called high intensity

discharge or 'I* lam&s. !i&'inten#it* di#c'ar&e la$+# C'I* lam&sB are a ty&e of electrical gas

discharge lam& 4hich &roduces light (y means of an electric arc (et4een tungsten electrodes housed

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inside a translucent or trans&arent fused uart? or fused alumina arc tu(e. %his tu(e is filled 4ith

(oth gas and metal salts. %he gas facilitates the arcs initial stri7e. 2nce the arc is started5 it heats and

e+a&orates the metal salts forming a &lasma5 4hich greatly increases the intensity of light &roduced (y

the arc and reduces its &o4er consum&tion. 'ighintensity discharge lam&s ma7e more +isi(le light &er

unit of electric &o4er consumed than fluorescent and incandescent lam&s since a greater &ro&ortion of

their radiation is +isi(le light in contrast to heat. Li7e fluorescent lam&s5 'I* lam&s reuire a (allast to

start and maintain their arcs. >nli7e thermal solid sources 4ith continuous s&ectral emission5 radiation

from the gas discharge occurs &redominantly in form of single s&ectral lines. %hese lines may (e used

directly or after s&ectral con+ersion (y &hos&hors for emission of light. *ischarge lam&s generate light

of different color uality5 according to ho4 the s&ectral lines are distri(uted in the +isi(le range.• 'I* lam&s are ty&ically used 4hen high le+els of light o+er large areas are reuired5 and 4hen energy

efficiency andor light intensity are desired. %hese areas include gymnasiums5 large &u(lic

areas5 4arehouses5 mo+ie theaters5 foot(all stadiums5 outdoor acti+ity areas5 road4ays5 &ar7ing lots5 and

&ath4ays

• $actors of 4ear come mostly from onoff cycles +ersus the total on time. %he highest 4ear occurs 4hen

the 'I* (urner is ignited 4hile still hot and (efore the metallic salts ha+e recrystalli?ed. 3estri7 time of

'I* lam& is a(out 1 minutes.

• @arieties of 'I* lam&s include

• Mercury @a&our Lam&

•

Metal 'alide Lam&• Sodium @a&our Lam&

•

3. LED La$+

•

• LE* lam&s are the ne4est addition to the list of energy efficient light sources. LE*s emit light in a

+ery small (and of 4a+elengths. 6ut general&ur&ose lighting needs 4hite light. %o emit 4hite light from LE*s

reuires either mixing light from red5 green5 and (lue LE*s5 or using a &hos&hor to con+ert some of the light to

other colors.

• 3#6 4hite LE*s uses multi&le LE* chi&s5 each emitting a different 4a+elength5 in close &roximity to

generate the (road s&ectrum of 4hite light. %he ad+antage of this method is that the intensity of each

LE* can (e ad8usted to JtuneJ the character of the light emitted. 6ut colour rendering of these lights are

&oor and has high &roduction cost.

• Phos&hor con+erted LE*s uses one short4a+elength LE* Cusually (lue5 sometimes ultra+ioletB in

com(ination 4ith a &hos&hor 4hich a(sor(s a &ortion of the (lue light and emits a (roader s&ectrum of

4hite light. %he ma8or ad+antage is the lo4 &roduction cost. %he color rendering index can range from

less than 0 to o+er 05 and color tem&eratures in the range of !00 H u& to 000 H are a+aila(le. %his

is the most 4idely used LE*.

•

• Efficiency of LE* de+ices continues to im&ro+e5 4ith some chi&s a(le to emit more than 100 lumens

&er 4att. LE*s do not emit light in all directions5 and their directional characteristics affect the design of lam&s.

%hus illuminating a flat defined area reuires less Lumen com&ared to light sources 4hich 4ould need reflectors

or lenses to do the same. $or illuminating an "-0O or(it5 the (enefits of LE* are much smaller.

• LE*s are degraded or damaged (y o&erating at high tem&eratures5 so LE* lam&s ty&ically include heat

dissi&ation elements such as heat sin7s and cooling fins. A single LE* is a lo4+oltage solidstate de+ice and

cannot (e directly o&erated on standard high+oltage A) &o4er 4ithout circuitry to control the current flo4

through the lam&.

• Assem(lies of high &o4er lightemitting diodes can (e used to re&lace incandescent or fluorescent

lam&s. Some LE* lam&s are made 4ith identical (ases so that they are directly interchangea(le 4ith

incandescent (ul(s. )om&ared to Incandescent or )$L (ul(s5 LE* (ul(s are more efficient and offer lifes&an of "05000 or more hours5 reduced if o&erated at a higher tem&erature than s&ecified. Se+eral

com&anies offer LE* lam&s for general lighting &ur&oses. %he technology is im&ro+ing ra&idly and

ne4 energyefficient consumer LE* lam&s are a+aila(le. LE* lam&s are more en+ironmental friendly

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as they didn


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•

•

•

•

•

•

•

•

/.2 C'oo#e e%%icient li&'t #ource#8 e#t #uitale %or t'e +ur+o#e

•

• *esigning lighting in a lo4 car(on (uilding reuires s&ecifying the right light source for the 8o(5 4hich

includes not only energy efficiency (ut a num(er of other considerations. An efficient (ut ina&&ro&riateCe.g. &hotometrically or startu& timeB lam& cannot (e considered to (e sustaina(le. Im&ortant

&arameters that should (e considered &rior to select a light source are

•

)ost Co&erating ca&ital costB

Luminous Efficacy

)olour 3endering Index

)olour %em&erature

Lam& life

3un u& time

*imming &ossi(ility

En+ironment effects

able 2: recommended illuminance leels (source:SLEMA)1


13/18

• $or domestic &ur&oses main com&etitors are Incandescent5 )$L and LE* lam&s. LE*s are still

de+elo&ing technology and ne4 lam&s 4ith ne4 features are coming to the mar7et.

• )ost Effecti+eness

• %o com&are the cost effecti+eness of these three light sources5 4idely a+aila(le characteristics

of the lam&s in the mar7et are considered. %otal monthly cost of a (ul( in a ty&ical house5

4or7s hours &er day is com&ared among these three technologies.

• %o calculate the o&erating cost5 unit electricity cost is ta7en as 3s10.0 Caccording to the

domestic tariff rates if the units consumed are lee than 0B.

• • Incandescent • )$L • LE*

• Lumen out&ut ClmB • -0 • -0 • -0

• Po4er C=B • -0 • 11 •

• Efficacy Clm=B • 11 • -0 • 0

• Life time ChB • 1000 • /000 • 0000

• )ost of one lam& C3s.B • , • "0 • 100

• Monthly )a&ital cost C3s.B

• Cfor hdayB• -. • -.0 • ,.0

• 7=h consumed

• Cfor hdayB• .0 • 1.- • 1."

• Monthly 2&erating cost C3s.B

• Cfor hdayB• ,.0 • 1."" • 1,.1/

• Monthly %otal cost C3s.B

• Cfor hdayB• 101.! • !"./" • 1/.-/

• Net Sa+ing o+er Incandescent • • -; • /1;

•

•

• 'ence (oth )$L and LE*s are cost effecti+e light sources. Many go+ernments ha+e introduced

measures to (an the use of Incandescent (ul(s due to their &oor efficiency.

• Lam& life of LE*s is much higher than )$Ls. Num(er of S4itching cycles affect the lam& life of )$Ls

+ery much. Most )$L lights o&erate for "0000 s4itching cycles according to the manufacturer


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• Energy la(eling ma7es the consumer a4are of the energy consum&tion le+els and energy efficiency

rating of energy a&&liances in their &urchasingK shortly it ena(les the consumer to identify 4hether that

&roduct sa+es energy or is an energy gu??ler. SLSEA is the authoritati+e agency and SLSEA in

colla(oration 4ith the SLSI im&lement the energy standards and la(eling &rogram. %he first Energy

La(el introduced in Sri Lan7a 4as for )om&act $luorescent Lam&s C)$LsB in the year !000. )$L 4as

selected as the first item for energy la(eling &rogram since it reuired hea+y &romotion.

• >&on the +alue for the &erformance grading Star 3atings are assigned. %he higher the num(er of stars5

the more the energy efficiency of the )$L. Efficacy of the lam& contri(utes 0; for the &erformance

grading.

•

•

•

•

•

•

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/.3 Select -e#t Li&'t %ittin&8 #uitale %or t'e +ur+o#e

• It is im&ortant to use suita(le light fittings to direct light from the source to the 4or7ing area. Luminaire

includes reflectors5 refractors5 diffusers and filters to direct the light to the tas7 surface 4ith maximum

efficiency 4ithout resulting in direct glare5 +eiling reflections or excessi+e (rightness ratios. It is

essential to use luminaire for fluorescent tu(es.

• *ifferent lam& technologies and different lighting en+ironments reuire different luminaire

construction &rinci&les and features. Most 'I* lam&s and LE* lam&s reuire thermal control

mechanism to control the internal tem&erature of the luminaire for &ro&er 4or7ing of the lam&.Although some amount of energy is lost and reduces the efficiency of lam& due to the o&tic

controlling5 luminaire hel&s to &ro+ide good uality light out&ut for reuired &ur&ose. Some

times luminaires are used only for the decorati+e &ur&oses 4ithout considering a(out other

factors. %his cause in +ain energy lost.

Source : SLSEA


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/./ Li&'tin& "aintenance

• Maintenance is +ital to lighting efficiency. Light le+els decrease o+er time (ecause of aging

lam&s and dirt on fixtures5 lam&s and room surfaces. %ogether5 these factors can reduce total illumination

(y 0 &ercent or more5 4hile lights continue dra4ing full &o4er. %he follo4ing (asic maintenance

suggestions can hel& &re+ent this.

• )lean fixtures5 lam&s and lenses e+ery - to !, months (y 4i&ing off the dust.• 3e&lace lenses if they a&&ear yello4.

• )lean or re&aint small rooms e+ery year and larger rooms e+ery ! to " years. *irt collects on

surfaces5 4hich reduces the amount of light they reflect.

• )onsider grou& relam&ing. )ommon lam&s5 es&ecially incandescent and fluorescent lam&s5 lose !0

&er cent to "0 &er cent of their light out&ut o+er their ser+ice life. Many lighting ex&erts recommend

re&lacing all the lam&s in a lighting system at once. %his sa+es la(or5 7ee&s illumination high and

a+oids stressing any (allasts 4ith dying lam&s.

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/. "a)i$u$ u#e o% da* li&'t

• Physically5 daylight is 8ust another source of electromagnetic radiation in the +isi(le range.

Physiologically5 daylight is an effecti+e stimulant to the human +isual system and the human circadian

system. Psychologically5 daylight and a +ie4 out are much desired and5 in conseuence5 may ha+e

(enefits for human 4ell(eing.

• As a tro&ical country Sri Lan7a get daylight more than 10 hours &er day 4ithout seasonal +ariation. *ay

light is a natural and free light source and lighting for day time can (e achie+ed from daylight 4hich

reduces the cost of lighting. 6ut solar radiation contains heat energy and it causes thermal discomfort or

increasing the load on cooling system. #lare occurs 4hen a (right light source such as the sun is in thefield of +ie4 of users. It can also occur 4hen reflections of the sun are in the field of +ie4.

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Figure +: Di#erent types of luminaires


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• 9indo:# are the ty&ical daylight &ro+ider for the (uildings. Si?e and &osition of the 4indo4s has a

great influence on daylight condition inside the (uilding. 'eat generation and glare can (e reduced (y

reducing the direct sun light in to the (uilding. %his can (e done (y

• A+oid &lacing the 4indo4s on east and 4est of (uildings

• >se shadings such as external o+erhangs

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• *ou(le gla?ed 4indo4s can (e used to reduce the heat entering 4ith solar radiation. It reduces theheat transmission (et4een inside and outside 4hile allo4ing light to transmit. 6ut they are ex&ensi+e

• Roo% li&'t# can also used to increase the day light entering the (uilding. 3oof lights are a gla?ed

o&ening in the roof of a (uilding.

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• Li&'t Pi+e# is another method to increase day light in the (uilding. In this method Sunlight is

collected (y fixed mirrors or (y sun trac7ing mirrors CheliostatsB and trans&orted into the

(uilding through light &i&es 4hich can also trans&ort and distri(ute the electrical lighting

from a centrally located electrical light source.

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/.4 Li&'tin& Control

• )ontrolling the light out&ut of a Lighting system is essential for the efficiency of the system. %his

controlling can (e onoff controlling or light out&ut le+el controlling. Also Light control can (e doneautomatically or manually.

• Light out&ut le+el +ariation is accom&lished (y using a rheostat in the &ast (ut it is +ery inefficient as

there is a &o4er loss in the rheostat too. In modern controllers they use solid state de+ices such as S)3

CSilicon )ontrolled 3ectifiersB and o&erate (y turning the lights on and off 1!0 times a second. %he

&ro&ortion of ontime determines the 4attage and the a&&arent (rightness.

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• Automated lighting control can (e done de&ending on

• %he occu&ancy

• *ay light le+el•

• If there is no lighting control system5 the out&ut is same for all time e+en if there is considera(le amount

of sun light inside the room. %his is miss&end of electrical energy. It can (e reduce (y using a light

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Figure ,: E-ternal oer$angs to reduce direct

Figure .: /oof lig$t


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controller 4hich is sensiti+e to the day light intensity. Photo sensors such as &hoto resistors5 &hoto

transistors and &hoto cells can (e used as sensors to detect day light le+el.

• And some times the occu&ants of the (uildings forgot to s4itch off the light 4hen they lea+e the

(uilding. %his 4astage can (e reduced (y using controllers sensiti+e to the occu&ancy. I3 (ased

occu&ancy sensors can (e used to detect the occu&ancy of the room.

• %imers can also (e used to control the lights.

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In modern control systems a+aila(le in the mar7et all t4o features are a+aila(le. %hey control the lightout&ut de&ending on the occu&ancy and the day light intensity inside the room.

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/.; Ot'er $et'od# to i$+rove t'e e%%icienc* o% t'e li&'tin& #*#te$

• *ecorate rooms 4ith light colours. Light coloured 4alls5 ceilings5 tiled floors reflect light than dar7

colours.

• >se tas7 lighting 4here e+er as &ossi(le. *irecting the light out&ut to the 4or7ing surface increases

the efficiency

• >se Electronic (allasts instead of electromagnetic (allasts

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. CONCLUSIONS

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• Efficient lighting system should contain•

Efficient light source (est suita(le for the &ur&ose

Luminaire (est suita(le for the &ur&ose

Light control system

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• LE* and )$L (ul(s are more efficient and cost effecti+e than Incandescent lam&s and Incandescentlam&s should re&lace 4ith )$L or LE* lights

• LE* lam&s are more en+ironment friendly than the )$L lights5 (ecause they didn


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RE(ERENCES

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1. Lighting 'and(oo75 !00 (y Society of Light Lighting

!. #uide (oo7 energy efficient electric lighting for (uildings (y E)6)S". Lighting 3eference #uide (y Natural 3esources )anada

,. )ode of &ractice for energy efficient (uildings in Sri Lan7a !00/ (y SLSEA

. %he lighting hand(oo7 for utilities from 3)L C3egional )enter for LightingB

-. Lighting $undamentals 'and(oo7 from 3)L

. Light and the En+ironment (y 2sram

/. Lighting 'and(oo7 (y Illuminating Engineering society of North America

. 2LE* technology (y 2sram

10. htt&:444.rclsa.net

11. htt&:444.energy.go+.l7 CSri Lan7a Sustaina(le Energy AuthorityB

1!. htt&:444.slema.org.l7 CSri Lan7a Energy Managers AssociationB

1". htt&:444.4i7i&edia.org

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artficial lighting

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