street lighting technology comparison

8/11/2019 Street Lighting Technology Comparison

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Street lighting technology

comparisonStreet lighting today

Today, street lighting commonly useshigh-intensity discharge lamps, often HPS high pressure

sodium lamps. Such lamps provide the greatest amount of photopic illumination for the least

consumption of electricity. However when scotopic/photopic light calculations are used, it can been

seen how inappropriate HPS lamps are for night lighting. White light sources have been shown to

double driver peripheral vision and increase driver brake reaction time at least !". When S/P light

calculations are used, HPS lamp performance needs to be reduced by a minimum value of #!".

$ study comparing metal halide and high%pressure sodium lamps showed that at e&ual photopiclight levels, a street scene illuminated at night by a metal halide lighting system was reliably seen

as brighter and safer than the same scene illuminated by a high pressure sodium system.

'ew street lighting technologies, such as induction or LED lights, emit a white light that

provides high levels of scotopic lumens allowing street lights with lower wattages and

lower photopic lumens to replace existing street lights. (ormal specifications around

Photopic/Scotopic ad)ustments for different types of light sources enables municipalities and street

departments to test, implement and benefit from this new technologies.

*ead more about Photopic and scotopic vision here.
http://www.grahlighting.eu/en/component/content/41-learning-center/53-studies#scotopichttp://www.grahlighting.eu/en/component/content/41-learning-center/53-studies#scotopic


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Street lighting technology comparison

light

technology

life time lumens per watt color temperature CRI (color rendering

index)

ignition time considerations

incadescent

light 1.000 -5.000 11 - 15 2.800K 40 instant very inefficient, short life time

mercury vapour

light12.000 - 24.000 13 - 48 4.000K 15 - 55 up to 15 min

very inefficient, ultraviolet radiation, con

mercury

metal halide

light10.000 - 15.000 0 - 100 3.000-4.300K 80 up to 15 min

high maintenance !" radiation, contamercury and lead, ris# of $ursting at the e

life

high pressure

sodium light12.000 - 24.000 45 - 130 2.000K 25 up to 15 min

lo% &'( %ith yello% light, contains mer

and lead

lo% pressuresodium light

10.000 - 18.000 80 - 180 1.800K 0 up to 15 minlo% &'( %ith yello% light, contains mer

and lead

fluorescent light 10.000 - 20.000 0 - 100 2.)00-.200K )0 - *0 up to 15 min!" radiation, contains mercury, prone to

$rea#ing, diffused non-directional lig

compact

fluorescent light12.000 - 20.000 50 - )2 2.)00-.200K 85 up to 15 min

lo% life + $urnout, dimmer in cold %ea

failure to start, contains mercury

induction light 0.000 - 100.000 )0 - *0 2.)00-.500K 80 instanthigher initial cost, limited directionalicontains lead, negatively affected $y h

/ light 50.000 - 100.000 )0 - 150 3.200-.400K 85 - *0 instant relatively higher initial cost

Incandescent lamps

+ncandescent amps are -standard electric light bulbs that were introduced more than ! years

ago by Thomas 0dison. They have the lowest initial cost, good color rendering and are

notoriously inefficient. They typically have short life spans and use significantly more watts than

1(s and halogen lamps do to produce the same lumens, or light output. +ncandescent technology

produces light by heating up a metal filament enclosed within the lamp2s glass.

3ore than ninety percent of the energy used by an incandescent light bulb escapes as heat, with

less than 4" producing light. Their use is most common in areas prone to fre&uent theft or

vandalism of light fi5tures. +n these locations a very high rate of replacement may make a case for

use of these cheap light bulbs. $nywhere else they are too wasteful to make sense. $fter all, ! "

efficiency and a few hundred hours lifespan are difficult to consider when replacement with 06

systems use # times less energy.

High Intensity Discharge (HID) Lamps include:

3ercury 7apor lamps 8outdated and almost e5tinct9

3etal Halide lamps

High Pressure Sodium lamps 8HPS9


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Mercury Vapor Lamps

3ercury 7apor amps were introduced in :; that is, they get steadily

dimmer and dimmer with age while using the same amount of energy.

3ercury lamps developed in the mid :?4s were coated with a special material made of phosphors

inside the bulb to help correct the lack of orange/red light from mercury vapor lamps 8increasing the

color rendering inde581*+99. The @7 light e5cites the phosphor, producing a more AwhiteA light.

These are known as Acolor correctedA lamps. 3ost go by the A6BA designation on the lamp and have

a white appearance to the bulb. $s of 44High Pressure Sodium (HPS) lamps

HPS lamps were introduced around :#4 and are one of the more popular street lighting options,

the most efficient light source when compared to mercury vapor and metal halide lamps 8on a

Dlumen/ watt2 scale9. The disadvantage is that they produce narrow spectrum light mostly a sickly

yellow in color. These lights have a very low color rendering 'ndex and do not reproduce

colors faithfully. These lights do not find favor with police departments as it is difficult to

determine the color of clothes and vehicles of suspects from eye witness accounts in the event of a

crime. 1olor%corrected sodium vapor lamps e5ist but are e5pensive. These Acolor correctedA HPSlamps have lower life and are less efficient.

There are two types of sodium vapor streetlightsE high%pressure 8HPS9 and low%pressure 8PS9. =f

the two, HPS is the more%commonly used type. Low Pressure Sodiumlights are even more

efficient than HPS, but produce only a single wavelength of yellow light, resulting in a 1olor

*endering +nde5 of Fero, meaning colors cannot be differentiated. PS lamp tubes are also

significantly longer with a less intense light output than HPS tubes, so they are suited for low

mounting height applications, such as under bridge decks and inside tunnels, where the limited light


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control is less of a liability and the glare of an intense HPS lamp could be ob)ectionable.

$nother issue of HPS lights is that they contain to mg of mercuryfor a 44 watt bulb with an

average of ? mg per bulb. They also contain lead. @nsafe disposal of these bulbs can lead to

significant e5posure of human beings and wild life to mercury contaminated water and food. +ssues

with mercury contamination and customer preference for full spectrum light has been fuelling the

replacement of these lights particularly in areas like self managed residential comple5es where

people can directly pay for the &uality of light.

Fluorescent lamps

The fluorescent lamp first became common in the late :G4s. These lamps are a form of discharge

lamp where a small current causes a gas in the tube to glow. The typical glow is strong in ultraviolet

but weak in visible light. However, the glass envelope is coated in a mi5ture of phosphors that are

e5cited by the ultraviolet light and emit visible light. (luorescent lamps are much more efficient than

incandescent lamps, but less efficient than High Pressure Sodium.

The ma)or problems with standard fluorescent lamps for street lighting is that they are large, and

produce a diffused non%directional light. They are also susceptible to low voltage failure, prone to(rea#age of glass parts and contain harmful mercury. Therefore the fi5tures needed to be

large, and could not be mounted more than 4CG4 feet above the pavement if they were to produce

an acceptable light level. (luorescent lamps &uickly fell out of favor for main street lighting, but

remained very popular for parking lot and outside building illumination for roadside establishments.

Compact uorescent lamp

1ompact fluorescent lamps 81(9 have been used more fre&uently as time has improved the &uality

of these lamps. These lamps have been used on municipal walkways and street lighting though they

are still rare at this time. +mprovements in reliability still need to be made. Some issues with them

arelimited lumen output, high heat (uild upin the self contained ballast, low life)(urnout

due to fre*uent cycling +on)off of the lamp, and the problem where most fluorescent sources

become dimmer in cold weather +or fail to start at all. They also contain harmful mercury. 1(

efficiency is high and 1*+ is e5cellent around

with its light being Asoft whiteA around that color temperature. Higher color temperatures are

available.

Induction lights

+nduction based fi5tures are relatively new to the market. +nduction lamps use radio fre&uency or

microwaves to create induced electrical fields, which in turn e5cite gases to produce light. +nduction

lights have a rapid start-upand work at peak efficiency with minimal warm%up time, much like

06 technology. This technology has some advantages versus HPS technology in the areas of

efficiency and life cycle, however, initial cost barriers and the rapidly evolving nature of 06

technology have led to limited adoption of induction based roadway lighting systems. $nother

limitation of +nduction ighting is that it haslimited directionalitywhen compared to 06s. The

life of induction light is negatively affected by heat and they also contain lead.

L!D lights

ight emitting diodes are rapidly developing in light output, color rendering, efficiency, and

reliability.

$chieving good maintenance%free thermal management in an often hostile environment while

keeping product competitive is the largest challenge, which only few manufacturers managed to


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achieve. This latest high *uality LED technologies are already exceeding all other availa(le

technologies (y all technical parameters. $ccording to its numerous advantages, even higher

initial cost &uickly pays for itself due to vastly reduced cost of electricity and maintenance. Iut to

fully (enefit from outstanding advantages it is important to educate and recognie the

difference (etween low *uality and latest state of the art LED technologies, since low

*uality LED alternatives have *uic#ly spread all over the world.

Di"erence #et$een lo$ and high %uality L!Dstreet lights

06 technology has developed dramatically over the last few years. he production of LED

lighting luminaire is an extremely difficult processthat re&uires a combination of advanced

production lines, top &uality materials and high%precision manufacturing processes.

.ot many companies in the world meet the *ualitative standardsin the production of 06

lamps. Iecause 06 technology is increasing, there are a lot of ine5perienced producers of 06

street lights with very poor &uality on the market.

Poor *uality LED street lights can (e worse than other types of existing energy-saving

lamps on the mar#et, while high-*uality LED street lights exceed other types of street

lighting in all technical parameters/

There is currently lessthan 011 experienced manufacturers of LED street lightsin the world,

of which less than 01 are a(le to produce high-*uality LED street lamp with the highest

*uality standards. hose manufacturers are optimally exploiting full (enefits of LED

technology.

&eneral #ene'ts o high %uality L!D streetlights

Ielow listed benefits of 06 street lighting are related only to latest, high &uality 06 street lightsE

Less energy consumption

06 street lights use 21-314 less electricityand have at least 5 times the life expectancy

than regular High Pressure Sodium +HPS fixtures. 06 lamps are 6 times more energy

efficient than incandescent and twice as efficient as fluorescent lamps/

Higher eciency and lo$ light pollution due to directional light06 street lights with a lower lumen output can replace conventional lamps with a higher output.

(or e5ample, a G4W 06 street light can often replace an


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This alsodramatically reduces light pollution, which affects the mood of human beings,

navigation in birds and insects, mating behavior in animals and flowering in plants.

Long lie * up to +,,-,,, hours

06 street lights last much longer than conventional lamps +7 to 3 times longer. This results

in less e5pense in replacing the lights themselves but also the labor to replace the lamp is neededless often. This provides a great cost savings by itself.

$lso the loss of brightness or lumen depreciation is slower over the life of an 06 lamp than that of

a sodium or other lamp. So not only does the 06 have a longer life span than the conventional

lamp, but it stays (righter longer than other lamps. The long life span reduces maintenance

e5penses and makes these bulbs particularly suitable for difficult to reach locations and for

streetlights where maintenance costs can be significant.

&reat operating characteristics

06 operate at lower temperatures, are not sensitive to low temperature and unaffected by on off

cycling. This makes them safer, more efficient in cold environments8outdoor lights,

refrigerator lights and cold room lights9 and better for applications re&uiring fre&uent switching on

and off lights. These bulbs areshoc#s and vi(rations resistantmaking them the best choice forplaces like bridges.

.educing car#on ootprint

The carbon footprint of 06 street lights is smaller than other lights due to lower energy usage.

3oreover 06s last ; to 4 times longer than any other bulbs, further reducing the carbon footprint

of manufacture over the life time.

Dar/s/y riendly

Iecause of the directional light, light is carefully distributed e5actly where it is meant to go and

therefore there is no or little light which is wasted by illuminating the night sky. This is a

considerable plus especially if the local community has a 6arksky +nitiative.

0atural light specter * Color .endering Inde1

06 street lamps with color temperature G.!44%;.44 are rendering more natural light than the

yellow of sodium lamps or green of flourescent streetlights. $lsono ! or '8 radiationis emitted

from the 06 street lamps. 1olor rendering inde5 +98' is high +31-:1and displays natural

colors of illuminated ob)ects.

Free o harmul su#stances and lo$er en2ironmental impact$hen used up

06 luminaires contain no harmful substances, like mercury, lead or other haFardous chemical and

gasses. Spent 06 lamps can be thrown away without any special handling or disposal

re&uirement,since they are recycla(le and environmentally friendly. =ther light often have

haFardous materials such as lead and mercury which re&uire special handling and waste

management procedures which have both economic and environmental costs.

!asily controlla#le

The light is easily controllable with intelligent systems. The light can be turned on and off instantly

and can be dimmed for added energy savings at dawn, dusk, and also during hours of low


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traffic. Switching on-off and dimming does not affect the life-timeof the luminaire as in the

case of 1( lights.

street lighting technology comparison

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