Low-EnergyLEDLightingIs“StreetsAhead”BERwaystoexploittheadvantagesofLED(light-emittingdiode)technologyinstreetlightingaTTEreexpectedtoemergefromcollaborationbetweenuniversityresearchersandanLEDlightingspecialistcompany,bothintheUK.LEDsfirstappearedindigitalwatchesandcalculatorsinthe1970s.Today,thetechnologyhasprogressedtothepointwhereitcanbeusedtocreatedurableandcommunity-friendly,low-energystreetlighting.Thebenefitsincludelong-lifeexpectancy(upto100,000hours)togetherwithincreasinglyhigh-lightoutputinrelationtotheirsizeandenergyconsumption,makingLEDsarealisticalternativetoconventionalsodiumvapourunitsforgeneralanddirectionallighting.AndbecauseLEDsaresosmall,thepossibilitiesformanufacturerstocreatesleeker,smaller,lightweightluminariesaregreatlyextended.Importantly,LEDsarealsoenvironmentallyfriendlyandsafe.Theycontainnoglass,filamentsormercuryandsocanexperiencenoneoftheexplodingfailuresassociatedwithhalogenandHID(highintensitydischarge)lamps.Andtheyarefreefromthecostandrestrictionsofmercurydisposalthatisinvolvedwithsodiumvapourunits.Operatingatlow-voltagedirectcurrentensurescompleteconsumersafety.ColouredLEDmodulesareveryvividandevenmoreenergy-efficientthanwhitelightunits.InthelatestjointprojectbetweentheUniversityofManchester,northernEngland,andLEDlightingspecialistDialightLumidrives-acompanyfoundedbyasuccessfulformerstudentoftheuniversity-researchersintheSchoolofElectrical&ElectronicEngineeringareusingtheirexpertisetoinvestigatehowtightlypackedgroupsofLEDscanbemadetoworksafelyandreliably.LightingsolutionsthatuseLEDsinthiswayhavethepotentialtoreduceenergyconsumptionby25-50percent,dependingontheapplication.Butthermalandelectricalissuesatlightinglevelsof12,000lumensandabove(atypical60whouseholdlightbulbproduces800lumens)arebarrierstothewideradoptionofLEDtechnology.TheuniversityengineerswillbeworkingwiththeYork-basedDialightLumidrivestotackletoughissuessuchastheamountofheatgeneratedbyLEDspackedcloselytogether.BecausetheLEDmoduleswillbeusedoutside,theywillneedtoconsiderpracticalenvironmentalfactors,suchasthepossibilityofbirdsnestingoveravitalheatsink.Anotherhurdleispresentedbytheregulationsthatgovernaspectssuchasglareandlightpollution；directingtheLEDlightsourcesspecificallyontotherequiredareawillformaseriouschallenge.Theone-yearprojecthasbeenfundedbyagrantof175,000poundsfromtheUKgovernment,matchedbyasimilaramountcontributedbyDialight.Akeyaimoftheprojectistodevelopasolutionthatisveryreliablebutnotprohibitivelyexpensive.DrRogerShuttleworth,fromthePowerConversionGroupatManchesterUniversity,said:“LEDtechnologyfirstcametoprominenceininstrumentdisplaysinthe1970s,butweareincreasinglyseeingitusedinthingsliketrafficsignalsandcarlights.“Towardstheendofthe20thcentury,theold-fashionedsodiumstreetlightsthatmadeeverythinglookorangeweregraduallyreplacedbyhigh-pressuresodiumlamps.Whilethesearebrighterandmoreaestheticallypleasing,andcanhelptacklestreetcrimeandanti-socialbehaviour,theyarealsolessenergyefficient.“Withtheenvironmentatthetopofthepublicandpoliticalagenda,energysavinghasbecomeaveryimportantissue.WhenyouconsiderhowmanystreetlightsthereareintheUKalone,itiscleartherearesomebigopportunitiesforenergyandcostsavings,”headded.DialightLumidrivesmanagingdirectorGordonRoutledgestudiedelectricalandelectronicengineeringattheUniversityofManchesterInstituteofScience&Technology(UMIST),graduatingin1996.Heexplained:“LEDsareontracktobecomeamajorsourceoflightingoverthenextdecade.Althoughsignificantinvestmentison-goinginthecoredevelopmentoftheLEDs,thesurroundingtechnologydevelopmentisbeinglefttomanufacturerswhohavelittleknowledgeofelectronicsorLEDs.“WeareproudtobeworkingwiththeUniversityofManchestertodeveloptechnologywhichwilldrivetheadoptionofthisrevolutionarylightingsourceineverydayapplications,”headded.Althoughhigh-pressuresodiumvapourstreetlighting-commonacrossmuchofEurope-givesanefficiencyofabout85lumensperwatt,heclaimedthatLEDtechnologywasalreadyontracktoexceed150lumensperwattandpredictedthisfigurewouldrisefurtherasnewsemiconductordevelopmentsoccur.Aswellascuttingenergyconsumptionandoverallrunningcosts,researcherssaythatLEDstreetlightinghelpsreducelightpollution；theskyglowthatradiatesfrombigcitiescouldbecomeathingofthepast.ItisalsoproposedthatLEDstreetlightingcouldbecontrolledanddimmedwhennecessary.TheirlongerlifespanmeansthatLEDstreetlightsneedtobereplacedlessoften,reducingpotentialtrafficdisruptionandcouncilrepairbills.ThelifetimeoftheLEDmodulethatthecollaboratorsareworkingonisinexcessof10yearsinaroadlightingapplication,somefourtimeslongerthanaconventionalstreetlight.AlthoughLEDsdoexperienceagradualandpermanentreductioninlightoutputduringtheirnormaloperatinglife-causedeitherbyareductioninthelight-generatingefficiencyoftheLEDdie,orareductionoftheopticalpathwithintheLEDpackage-theDialightstreetLEDsareexpectedtoprovideabout70percentoftheiroriginallightoutputafter50,000hoursor10years,providedthattheyarenotoverdriven.Thisisnotassignificantasitsoundsbecausethehumaneyeisrelativelyinsensitivetochangesinlightoutput,andareductiontoabout50percentisnecessarytocreateanoticeablechange.Itis,saysthecompany,easytoconvertexistingstreetlightingtoanLEDsourcebecausenoelectronicsskillsarerequired.IthasbeendevelopingandexploitingLEDtechnologyforlightingapplicationsforalmostfiveyears,withasuccessfulproducerangesuppliedtomanyoftheworldsleadingequipmentmanufacturers.道路照明將率先使用低能耗的發(fā)光二極管照明技術(shù)英國的一所大學(xué)的研究人員和一個(gè)發(fā)光二極管（LED）專門企業(yè)合作，期望能夠開發(fā)出將LED技術(shù)優(yōu)勢利用在道路照明中的最佳方法。LED最先于上世紀(jì)70年代出現(xiàn)在數(shù)字手表和計(jì)算機(jī)中。今天，這項(xiàng)技術(shù)取得了進(jìn)步，可以用來制造耐用、低能耗且對社區(qū)友好型的道路照明設(shè)備。其好處有：預(yù)期壽命長（可達(dá)100,000小時(shí)），根據(jù)型號大小以及能量消耗率逐漸增加高亮度輸出，對于普通照明和指示燈來說，可以用LED來實(shí)際替代傳統(tǒng)的鈉蒸汽單元。而且，由于LED體積是如此之小，所以制造商用它來制造更加圓滑、體積更小、輕量級的發(fā)光體的可能性就大大增加了。重要的是，LED對環(huán)境友好，而且還安全。它不含玻璃、燈絲或汞，所以不會發(fā)生由于鹵