Project TS1 Pavel Parushev

8/6/2019 Project TS1 Pavel Parushev

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Pavel Nedkov Parushev10258

Technology Specialization 1

LED lamps the lighting of the future.

(Street lighting)

Source:http://www.gemmalighting.com/products/jupiter/

Supervisor: Lars Bkgaard


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Tabl

1 Introduction ................................ ................................ ................................ ................................ ..... 3

1.2 Problem Formulation................................ ................................ ................................ ............................. 4

1.3. Main Question................................ ................................ ................................ ................................ ....... 4

1.4.Secondary questions................................ ................................ ................................ ............................. 4

1.5 Delimitations ................................ ................................ ................................ ................................ ......... 4

2 Method of data acquisition ................................ ................................ ................................ ......... 5

2.1. Model... ................................ ................................ ................................ ................................ ................. 5

2.2 Research philosophy................................ ................................ ................................ ............................. 5

2.3 Researchstrategy................................ ................................ ................................ ................................ . 5

2.4. Methodsusedintheresearch ................................ ................................ ................................ ............... 5

2.5. Empiricaldata ................................ ................................ ................................ ................................ ....... 5

3 Theoretical framework ................................ ................................ ................................ ................. 6

3.1. Whatis LED? ................................ ................................ ................................ ................................ ........ 6

3.2. HistoryofLEDs ................................ ................................ ................................ ................................ ..... 7

3.3. UseofLED lampsforstreetlighting ................................ ................................ ................................ ...... 8

4 Comparison of LED, HPS and Metal-Halide lamps................................ ............................ 8

4.1. Energyefficiency ................................ ................................ ................................ ................................ .. 8

4.2. Durability................................ ................................ ................................ ................................ ............ 10

4.3. Color. ................................ ................................ ................................ ................................ .............. 10

4.4. Lifeandlumenmaintenance ................................ ................................ ................................ ............... 11

4.5. Lightdistributionandglare ................................ ................................ ................................ .................. 12

4.6.Cost.. ................................ ................................ ................................ ................................ .......... 12

5 Analysis. ................................ ................................ ................................ ................................ ..... 12

6 Conclusion................................ ................................ ................................ ................................ ..... 13

7 Furtherwork ................................ ................................ ................................ ................................ .. 13

8 List of references ................................ ................................ ................................ ......................... 14


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1. IntroductionThe human kind has been searching for a way to illuminate the darkness since the very

early stages of the evolution. Fire has been a primary light source for ages and it was not until

recently that the electricity was found and this contributed to finding ways to convert it into

light. There are now many technologies that allow the transformation of electricity into light,

although we refer to all of them by the term lamps, mostly not paying attention to thedifference. Some of them are widely used while others have been forgotten to the history.

Today the mankind is not concerned with the questions about how to produce light, the

headline questions are about the energy efficiency, performance and greenness of thetechnology. The people are facing the negative effects of the pollution supplementing the

generation of electricity, and in addition to finding eco-friendly ways of production, they arealso trying to maximize the efficiency of the electric devices and reduce the use of electricity.

Improved ways of lighting that have better energy efficiency and also offeringequivalent light output are needed. The governments are also trying to prohibit the production

of lamps that have low energy efficiency and stimulate the companies to produce greenerlamps. In the recent years the fast evolution of a technology that has been there for a century,

is making it possible to produce light more efficiently. Light Emitting Diode is a simpletechnology that produces light with the use of very small amount of electricity. There have

been many problems that prevented this technology from being used for general illumination,but now it tends to be superior in every aspect compared to all other technologies except when

it comes to price.

This project has the goal to analyze the Light Emitting diode (LED) technology and

compare the key aspects to the other most used technologies when it comes to street lighting.

Are the LED lamps better compared to Metal-halide or High Pressure Sodium lamps? Are

they the light of the future? Please read further to find the answer to these questions!


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1.2. Probl ormulationLED has been rapi l devel ping in the last years, butis this new technology betterthan thetechnologies used now in terms of lighting capabilities, features, life expectancy, energyefficiency and price? Street lighting is a problem of great importance to communes all overthe world. A lot of energy is spent to bring some light during nighttime. This is needed inorderto prevent car accidents, thefts and in general - ease ourlife when itis dark.

1.3.Main questionDoes LED technology possess the required qualities to substitute the technologies used untilnow to illuminate the streets during darktimes?

1.4. Secondary questionsIs it affordable (initial cost + maintenance cost ?Whatis the reduction of CO2 emissions and energy consumption compared to the lamps useduntil now?What are the features of LED technology? Are they better compared to the features of the

othertechnologies that are used?Does it have any downsides?

1.5. DelimitationsUsage of LED lamps only for streetlighting (Roadway Lighting, Pathway Lighting, SidewalkLighting, Jogging and Bike Path Lighting)Technologies to review: Metal-halide (M ), High-pressure sodium (HPS), Light EmittingDiode (LED) based lamps


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2.Method of data acquisition

2.1. Model Desk study (Encarta, 2009)- assessment of existing data: an investigation of the available facts and figures relevant

to a specific issue before starting a new or more detailed study of it- This research is based on secondary data only or mostly

2.2. Research philosophy Post positivist (Research design, 2010)- Absolute truth out of this research can never be found.- This research is a process of making claims and then testing, refining or abandoning

some of them for other claims more strongly warranted.

- Data, evidence and rational considerations shape knowledge.- The research seeks to develop relevant, true statements that can serve to explain the

situation that is of concern or that describes the causal relationship of interest.

- Researcher must examine their methods and conclusions and control orlimit bias.- No matter how faithfully the scientist adheres to scientific method, research outcomes

are neither totally objective nor unquestionably certain.

2.3. Research strategy Inductive (Social research methods, 2006)Inductive reasoning works moving from the specific observations to broader generalizationsand theories (Figure 1). In inductive reasoning, we begin with specific observations and

measures, begin to detect patterns and regularities, formulate some tentative hypotheses thatwe can explore, and finally end up developing some general conclusions or theories.

Figure 1

Source: http://www.socialresearchmethods.net

2.4. Methods used in the research- Comparative analysis Comparison of the LED technology to HPS and

Metal-halide technologies

2.5. Empirical data- Collection from others studies and projects, data charts and articles

posted over the Internet.


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3.Theoretical framework

3.1. What is LED?Light Emitting Diode (LED) is solid state

semiconductor device which converts electricity intolight. In general the structure of a LED (picture 1)

consists of anode (positive electrode), cathode

(negative electrode), lead frame, semiconductor

material between the lead frame, and an epoxy

encapsulation to protect the lead frame and disperse

thelight.

The semiconductor material is the most critical part

of the LED. When electricity is applied to it light is

produced in the form of radiation. This happens due

to the fact that on the positive side there is a p-type

semiconductor and on the negative side there is a n-

type semiconductor. The semiconductor material isdoped with impurities to create a p-n junction.

This phenomenon is described in detail (How and

LED works, 2010).

Picture 1 LED structureSource:http://en.wikipedia.org/wiki/Light-emitting_diode

What happens as the electricity

jumps across the p-n junction is thatthe electrons from the n-type side

fill holes in the p-type side(picture 2). Through the process, the

electrons change up their state and jump from the negative side to the

positive and vice versa. During thisstate change, a photon is emitted.

More specifically, as electrons move

around orbiting a nucleus of an atom,

electrons with different orbits have

different amounts of energy.Electrons with orbits that are far

away from the nucleus have greater

energy and ones closer have less

energy.

Picture 2 P-N junctionSource:http:/ /www.todayifoundout.com/index.php/2010/03/how-an-led-works/


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In order for an electron to change its orbit, it needs to either lose energy or gain energy. What

we are interested in with LEDs are the electrons going from a higher orbit to a lower orbit,

this loss of energy results in the form of a photon of light. When the electrons from the n-type

side fill the holes in the p-type side, they lose energy in the form of these light photons. The

greater the energy release is, the higher the frequency of the light photon that is given off,

leading to color change.

If the frequency is within the human visible spectrum (the range our eyes can see), then wewill see the light being emitted by the LED. If we see no light (i.e. when the light emitted isin the invisible infrared spectrum), then we wont see it. But it can still be useful, such as in

allowing you to change the channel on our TVs (infrared LEDs are used in TV remotecontrols and many other places).

In LEDs, the light that is being emitted depends on the material being used and the currentthat is run through it. The light in a standard diode has the atoms arranged so that the electron

drop in energy is very short and the frequency of light given off isnt visible to our eyes,rather is in the infrared. So simply explained, LEDs that are produced with the intention to

give off lot of light are made of semiconductor materials that create a bigger drop in theelectrons orbit so that the frequency of the photon packet comes out in the human visual

spectrum. They can even be designed so that the amount of electricity flowing through them

will actually change the drop so multi-color LEDs can be produced .

3.2. History of LEDsThe first reports of Light Emitting Diodes date back in 1907, but it wasnt until 1962 when

the first practical LED was introduced as a low-intensity red LED. The creation of the first

blue indium gallium chip in 1993(Nichia Corporation, 2010) by Nichia Corporation allowedthe production of the first white LEDs by combining red, green and blue LEDs. The further

development of Nichia allowed the development of the first white LED in 1996(Nichia

Corporation, 2010) by adding a phosphor coating to the blue LED to create the wave shiftnecessary to produce light that appears white. These first white LEDs didnt have very good

efficacy. The development of LED technology in the next decade led to the introduction ofthe first high-brightness white LED in 2006. Since then many improvements have caused

their efficiency and light output to rise to levels that are nearing the theoretical maximum of

conversion energy into light. There are claims that efficiency of 200lm/watt has beenachieved in laboratory experiments and some even claim efficiency over 300lm/watt (Crystal

coat warms up LED light, 2008).A drastic change in design is being observed in the recent years since the designers are

striving to find the most effective design to achieve maximum efficiency in producing light.


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3.3. Use ofLEDlamps for streetli tingLighting the streets during nightis not an easy task and governments all overthe world spendmillions and even billions of dollars for electricity and maintenance bills every year.Something more efficient and long lasting is needed. It wasnt long afterthe introduction ofthe first high brightness white LEDs and the first LED streetlamp designs were presented andeven implemented in the beginning of year 2007. Since then many cities all overthe world aremaking and reali ing projects to replace part ofthe currentluminaries with LED ones.The technology is evolving at fast pace, and many different designs of street lamps areintroduced every month. Some designs include the specifically designed poles, which areintended to protect the lamp from the bad environmental conditions and the LEDs fromoverheating. The lamps are also equipped with a driver because although they are very energyefficient they tend to be high-powered and some designs use up to 250W.There are many other issues to consider in outdoor lighting but energy efficiency seems tohave the highest priority because ofthe long operating hours usually 8+ and the high powerconsumption involved. The next section of the project reviews in detail the different factorsthat are important when lighting big open space areas. Factors such as energy efficiency, aswell as differentissues related to durability, color quality, life and maintenance, light

distribution, glare and last but notleastimportant COST.

4.Comparison ofLED, HPSandMetal - halide lamps

4.1. Energy efficiencyEnergy efficiency is defined by the luminous efficacy of the light source the appropriate

power supply in lumens per watt (lm/W), optical efficacy ofthe luminary (light fixture), andhow well the luminary delivers light to the target area without casting light in unintended

directions. The goalis to provide the necessary luminance in the target area, with appropriatelighting quality, for the lowest power density. One step in comparing different light source

and luminary options is to examine luminary photometric files. A comprehensive photometrycomparison can be found from qualified independent or qualified manufacturer-basedlaboratories. The photometry should be based on an actual working product, not a prototypeor computer model.High-Intensity Discharge (HID) lamps such as MH and HPS are point sources and the opticaldesign forthese luminaries makes the area directly below the lamp to be much brighterthanthe areas farther away from the light source. In comparison LEDs are smaller and alsomultiple point-source having really good directional characteristics of the light that is beinggiven off, which allows better distribution ofthe light and results in a visible improvementinlighting large outdoor areas. Using LED based luminaries removes the factor over lighting

which may be described as a wasted energy, and also is irritating or even blinding the eyessince it forces adaption when going from brighterto darker areas.

Table 1 (next page) provides most ofthe important data for LED, HPS and MH outdoor area

luminaries, to illustrate the basic features of the different technologies. Lumen output andefficacy vary greatly across different outdoor area luminaries, so this data should not be used

to generali e the performance ofthe studied luminaries using the listed lamp types.


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Table 1Features Metal halide

High Pressure Sodium

Light HPS LEDStreetLight

Photometric Performance Very good Bad Excellent

Electric PerformanceElectric Shock Easy (High

Voltage)Electric Shock Easy (High

Voltage) Safe (Low Voltage)

Working Life Medium (15,000 hours) Short (5,000 hours)Quite Long (>50,000

hours)

Working Voltage Range Wide ( 20%) Narrow ( 7%) Wide ( 20%)

Power ConsumptionQuite High (200W

1000W) Quite High (200W 750W)Quite Low (60W

250W)

Start-up Speed Slow (Up to 5 minutes)Quite Slow (Over 10

minutes) Rapid (Instant)

Typical Efficacy 65-115 lm/watt about 100 lm/watt 60-200 lm/watt

Wattage equivalenttolight produced 160W 150W 100W

Colour Radiation Index(CRI) / Distinguish

Feature

Good, CRI 65-90(The Colour Of ObjectIs

Fresh, Veritable AndComfortable)

Bad, CRI 75(The Colour Of ObjectIs

Fresh, Veritable AndComfortable)

Colour Temperature

(in Kelvins) Medium (3000Kto 4000K) Low (2000Kto 3000K)

Ideal Colour

Temperature

(2800K 6500K)

Bad Glare No Harmful Glare Strong Glare (Dazzle) No Harmful Glare

Heating Serious (>300C) Serious (>300C) Cold Light (


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4.2. DurabilityOutdoor lights often become resting points for birds and collect all the dirt that is being

brought according to (Naomi Miller, 2008). The luminary should be made in a way that does

not collect and retain dirt or water on the top side, and the optical compartment should remain

clean for the LED luminary to reduce maintenanceand keep the illuminating characteristics.

Ingress Protection (IP) ratings are introduced to measure the luminaries resistance to dust and

moisture. The IP rating should be taken in consideration according to the conditions in which

the luminary will be used.

The luminaries are often exposed to extreme weather conditions like wind, rain, snow, hail,

frost, heat that may influence the lighting capabilities or even destroy the installation if not

properly protected. The durability characteristics of LED technology seem to be much better

than that of the HID luminaries (because there is no filament or glass) with the only exception

that LEDs are not very resistant to high-temperatures and thus must not be installed in placeswhere the temperatures go over 35 - 40 degrees Celsius or they must possess a good designto dissipate the heat that protects the LED from overheating.

4.3. ColorThe most efficient white LEDs have color temperature from 4500K to 6500K, which meansthey emit light that appears to be white to bluish-white which makes the objects that are

enlightened to appear bright and impress with their real colors. Some LED lamp

manufacturers mix LEDs with various color temperatures to reach desired color temperature

of the luminary that is most pleasant and gives appropriate coloring of the area that is

supposed to be lit. The color rendering varies according to manufacturer and model but in

general it is better than HPS (less than 50CRI) and the most common MH (around 65CRI).Usually LED luminaries have CRI over 75. The Color Rendering Index measures theadequacy of the light to make the objects color identification possible. CRI of 50 or more isusually enough to make clear distinction between do colors, but the more CRI the better.LEDs score another point in this feature competition (Picture 3).

Picture 3 Comparative spectral power distributions for HPS, MH, and LESource:http://apps1.eere.energy.gov/buildings/publications/pdfs/alliances/outdoor_area_lighting.pdf


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4.4. Life and lumen depreciationThe estimation of LED life is really problematic because of the long predicted lifetimes make

it impossible and impractical to test since the technology continues to evolve at fast pace,

outperforming previous test results. Most LED manufacturers define useful life based on the

estimated time at which LED light output will decline to 70% of its initial specifications,

often the declared life of the luminaries is 50,000 hours but some lamps are designed and

expected to have longer useful life and are claimed to last 100,000 and even 150,000 hours

(Naomi Miller, 2008). The manufacturers typically determine the maximum current and

junction temperature below which the LEDs are expected to have their useful life (produce

more than 70% of their initial light) for at least the claimed lifetime in hours. If the LEDs are

operated at lower current and/or exposed/maintained at lower temperatures, their useful life

may be greatly increased. In general, LEDs in well designed lamps are less likely to fail or not

meet their expected life while on the opposition the poorly designed LED luminaries mayexperience early failure or very fast decrease in lumen output. As previously mentioned the

thermal management of this technology is very crucial to the long-term performance of theluminary since heat tends to degrade or destroy the diodes and this leads to decrease in the

light output. The temperature of the junction in the diode determines its performance, thats

why heat dissipation and air flow must be designed to maintain a favorable operatingtemperature for both the LEDs and the driver. Some manufacturers provide the operatingtemperature specifications and charts explaining how temperature is related to the expected

light output and lumen decrease for the specific LED luminaries.All light sources experience a decrease in light output (lumen depreciation) over their

operating life. Lighting designers use mean lumens to make some base for comparison and

this is usually defined as luminous flux at 40% of the rated life, instead of the specified

lumens. For HPS lamps mean lumens are about 90% of initial lumens while MH lamps mean

lumens are about 75% of initial lumens (Naomi Miller, 2008). See Picture 4 for typical lumen

decline curves for these HID light sources and two sample curves for LEDs: one designed for

50,000-hour useful life (LED example 1) and one designed for longer life (LED example 2).

Picture 4 Typical lumen maintenance curves for HID sources, and estimated curves for LED.

Source:http://apps1.eere.energy.gov/buildings/publications/pdfs/alliances/outdoor_area_lighting.pdf


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4.5. Light distribution and glareSome LED luminaries need different optics than MH or HPS lamps because each LED is anindividual point source (NaomiMiller, 2008). Effective luminary design takes advantages ofthe directional nature ofthe lightthat LED produces and this may lead to lower opticallossesof the light, higher luminary efficacy, better light distribution over the intended area. Bettersurface enlightenment and higherlevels of verticalluminescence are possible using LEDs andspecially designed optics, in comparison to HID technologies. Photometric reports presentthe

pattern of light that is being emitted through the 90 (horizontal) plane and the 0 (vertical)plane. In general the LED show a reduction in luminous intensity in the 70 to 90 verticalangles which does not cause discomfort and disability glare to the people passing by. This isone of the most important qualities of LED lighting over the HID sources which blind thedrivers for example and may lead to incidents.

4.6. CostAs a comparatively new technology used for lighting, LED luminaries currently cost morethan the traditional HPS orMH light sources. The reduction in re-lamping cost and potential

power savings overtime with LEDs may reduce the overalllifecycle cost and may happen to

be even cheaper. Economic evaluation of LED outdoor luminaries is a hard task highlyspecific to the area that is to be lit, dependant on variables including electric demand (kW)and consumption (kWh) rates, maintenance costs, real usable life of the luminary, need forspecific optics and poles. LED outdoor lighting experiments documented by differentassociations have shown estimated payback from 3 years to more than 10 years. LEDtechnology is the perfect answerto some new requirements put by the governments over theworld. Some jurisdictions have implemented some steps to reduce the energy consumptionduring night. LEDs are not only energy efficient butthey possess one very important feature they can be designed to reduce the illumination of the luminary wheneverlightis not neededthus greatly improving the power savings.

5.AnalysisOn the basis ofthe collected data outdoor area lighting appears to be a promising applicationfor LED technology in addition new better products are being introduced on a regular basis.All LED and HID luminaries need careful information gathering and research in order toassess quality, performance, and overall value. The features of the LED luminaries varygreatly from design, and type ofthe LEDs used, manufacturer, and also the offered warrantyover the products. The provided data is too general and is intended to give only slightoverview on the outdoor lighting picture. In summary LED technology offers better powerefficiency, reduced CO2 emissions, longerlife, better Color Temperature and Color Radiation

(it gives better perception and does notirritate the eye), the produced lightis spread overtheground more even then MH and HPS (there are no brighter spots that may blind you for a

moment when you are driving), LED technology posses the feature to be turned on instantlyand is more durable in many aspects over the competition. One of the main problems atthis

pointis the cost ofthe products which is few times higher than the competitive products, butthis difference is being compensated over time due to the longer useful life, and the energysavings. There are a lot more considerations that come to mind when considering changingthe currentluminaries with LED ones. Some ofthe lamps are designed to be compatible withthe currently used poles, so a simple replacement ofthe lamp with LED one is allthat has to


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be done in order to enjoy the benefits of it, but since LED produce directional light somespecifically designed poles may be implemented along with the lamps itself for even betterresults. The optics used to spread the light around is also important and may greatly improvethe lighting and color rendering features of LED.

6.ConclusionThe comparison ofthe different features and specifications ofthe streetlighting technologiesin this report made it unquestionably clear who is the clear winner out of the competitionwhen it comes to streetlighting and although there are a lot of considerations that botherthelighting experts LED technology definitely wins over HPS and MH. LED is one ofthe fastestdeveloping technologies in the recent years and is finding implementation in many areas ofthe human life. With the increasing effectiveness and light capabilities claiming to haveachieved 300lm/watt in laboratory settings LED luminaries are expected to start dominatingthe luminary marketin the next few years. These figures are nearing the theoretical maximumin efficiency of converting electricity into light and unless some revolutionary and innovativeway to produce light withoutthe use of electricity LED technology are going to be the mostdesired one in Streetlighting for a long time.

7.Future workMore detailed research may be conducted with concrete specifications and comparison of

particular products and features. Practical experimentation and testing with real productspreferably the newest LED lamps available on the marketis recommended. There is a seriousconcern aboutthe life expectancy ofthe whole LED luminary, because itis claimed to last atleast 50,000 hours which is quite a long time to test it in practice and manufacturers usually

provide 3-5 years of warranty on their LED products while they are expected to have lifenearing 10 years. This is an interesting aspectto be taken into account and tested if possible.If a laboratory setting is available to provide the opportunity to test and experiment in new

better and more effective designs of LED and LED lamps this could be a possiblecontinuation of the following research. At the current point this project is just a briefintroduction of the outdoor lighting and a research on the benefits and the features of LEDtechnology. Another point of interest may be to study how the poles design influences thelongevity of the luminary and also the light distribution, although the LED lamps arecompatible with the current poles.


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8.List of referencesSocial research methods,[online] (updated 2006) Available at:http://www.socialresearchmethods.net/kb/dedind.php

[accessed on 23.12.2010]

Research design,[online] (updated 2010) Available at:http://mis611.wikidot.com/creswell-chapter-1[accessed on 5.1.2011]

Encarta,[online] (updated 2009) Available at:


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High Pressure Metal halide Lamps,[online] (updated 2009) Available at:http://www.linderlight.com/metal_halide2.html[accessed on 4.1.2011]

Metal Halide Technology,[online] (updated 2010) Available at:http://www.venturelighting.com/TechCenter/Metal-Halide-TechIntro.html[accessed on 4.1.2011]

Streetlighting products specifications,[online] (updated 2010) Available at:http://ledlight.osram-os.com/applications/street-led-lighting/street-lighting-products-specifications/[accessed on 4.1.2011]

Researchers on LED Streetlights,

[online] (updated 2010) Available at:http://solist1.com/index.php?option=com_content&view=article&id=159:researchers-find-led-streetlights-are-most-cost-effective-and-environmentally-friendly&catid=46:news&Itemid=68[accessed on 4.1.2011]

Outdoor Area Lighting, NaomiMiller[online] (updated June 2008), Available at:http://apps1.eere.energy.gov/buildings/publications/pdfs/alliances/outdoor_area_lighting.pdf[accessed on 5.1.2011]

OSRAM Opto Semiconductors[online] (updated 2010), Available at:http://www.osram-os.com[accessed on 5.1.2011]

Wright, M., December 2010. LED momentum builds at annual Street and Area Lightingconference pp.37-42 [online] Available at: [AccessedDecember 2010].

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