LED professional Review (LpR) – Sept/Oct 2024 – LpR#105

IntelligentLighting, GlobalStandards,and Health

WelcometotheSept/Oct2024issueofLEDprofessionalReview,where weexplorethelatestadvancementsshapingthefutureoflighting.As smartlightingtechnologyevolves,itmovesbeyondautomationto becomemorehuman-centric.Wedelveintothelimitationsofmotion sensorsandhownewtechnologieslikeCO2 andmicrowavesensors, combinedwithAI,arecreatingmoreresponsiveandpersonalizedlighting. WhatrolewilldataandAIplayinmakinglightingmoreadaptableto humanbehaviorandneeds?

Inourexclusiveinterview,TonyBergen,VicePresidentTechnicalofthe CIE,shareshisinsightsintogloballightingtrends.FromAIandintegrative lightingtosustainability,hediscussesthechallengesofshapingan industrythatbalancesinnovationwithhumanwell-beingand environmentalresponsibility.

ThisissuealsohighlightstheworkofLichtvisionDesignattheIFCNanjing ShoppingMall,wherelightingdesignblendsfunctionalityandluxuryto enhancetheretailexperience.Lightingbecomesakeyelementincreating atmosphereandguidingvisitorsthroughthespace.

Inofficelighting,newzonalstrategiesareleadingtheway,reducingenergy consumptionwhileimprovingcomfortandproductivity.Movingawayfrom uniformlightinggrids,thesestrategiesarereshapingworkenvironments. Wealsodiveintohorticulturallighting,whereLEDsaretransformingthe agriculturalsectorbyimprovingcropqualityandreducingproductiontime. Withtailoredlightspectraandhigherefficiency,LEDsarehelpinggrowers meetmoderndemands.

Finally,don’tmissthearticleontheupcomingLpSDigitalSummitand AwardsinDecember,featuringpresentationsanddiscussionsonthe latestinnovationsinlighting.

Thisissueispackedwithcutting-edgeinsights,makingitessentialreading foranyoneinvestedinthefutureoflightingtechnology,design,and sustainability.

Enjoyyourread!

YoursSincerely,

SiegfriedLuger

8 WillAIMakeResearchintoHuman ResponsetoLightObsolete? byProfessorJean-PaulLINNARTZ,Professorat EindhovenUniversityofTechnology

CIEINTERVIEW

20 TonyBERGEN,Vice-PresidentTechnical ofCIE compiledbyEditors,LEDprofessional

PROJECTS

26 6-starHospitalityApproachforthe ShoppingMallNanjinginChina byLichtvisionDesign

LIGHTINGDESIGN

36 TransformingGeneralLighting–The Cost-savingPotentialofZonalLighting byMatthiasBoeserandDr.ThomasSchielke, ERCO

LIGHTINGRESEARCH

42 DaystoRe-entrainmentFollowingthe SpringandAutumnChangesinLocal ClockTime:BeyondSimpleHeuristics byMarkS.Rea,RohanNagare,JohnD. Bullough,andMarianaG.Figueiro

HORTICULTURALLIGHTING

52 LEDLightinginHorticulturalApplications –A2024Update byProf.ErikRUNKLE,MichiganStateUniversity

EVENTS

54 LEDprofessionalSymposium2024LpS DigitalSummit&LpSAwards byLugerResearche.U./LEDProfessional

LPSDIGITALTALKS

56 ExpertTalksonLight–TimeMatters,ShiningLightonMetabolic Health

ProfessorJean-Paul LINNARTZ

Jean-PaulLinnartzisProfessorin theSignalProcessingSystems group.Hefocusesonalgorithms forintelligentlightingsystemsand wirelessopticalcommunication, e.g.LiFi.Heisalsoan internationallyrecognizedthought leaderinthefieldofsecuritywith noisydata.

Jean-PaulLinnartzobtainedhis MScinElectricalEngineeringfrom EindhovenUniversityof Technology(TU/e)in1986.Hedid hisPhDatDelftUniversityof Technology,graduatingin1991on trafficanalysisinWireless Networks.AsAssistantProfessor attheUniversityofCaliforniaat Berkeley,heworkedon autonomousdrivingandwireless multimedia(Infopad).Afterbeing appointedasAssociateProfessor atDelftUniversityofTechnologyin 1995,LinnartzjoinedPhilips Research,becomingSenior Directorin2001andResearch Fellowin2013.From2018-2024, hewaswithSignify.In2006,he returnedtoTU/easParttime ProfessoratTU/e.

www.tue.nl/en

https://www.linkedin.com/in/linnartz/

WillAIMakeResearchintoHumanResponseto LightObsolete?

Smartlightingisdesignedtobe intelligent,yetweoftenseecartoons pokingfunatit.Pictureanofficeworker deeplyfocusedondeskwork, developinggreatideas.Suddenly,the lightsswitchoff,leavinghimindarkness becausethesensors,detectingno motion,turnofftosaveenergy.

WhenIenteredthelightingfield,Iwas struckbythevastknowledgeofhow peopleexperiencelight.Ibeganreading PeterBoyce’sbook,hopingtousethis informationtoenhancelightingcontrol. WhileIwasawareofthelimitationsof motionsensorsandprocessors,Isaw manynewsensortypesemerging,like microwave,CO2,andlightsensors,as wellashowsignalscouldbeprocessed moreefficiently.Itseemedthatsmart lightingcouldgobeyond“IFpresence THENkeeplightson”andbecomemore human-centric.

Humanperceptionmodelsare commonlyused.Forexample,digital videoreliesonsuchmodelstoavoid noticeableartifacts.Theflickercaused byLEDshasalsobeenwidelystudied. Yet,Irealizedthatmostreportsonhow lightingaffectshumanproductivity followedstricthypothesistesting.These evaluations,doneincontrolledlab settings,determineiflightingeffects producesignificantdifferences. However,thesestudiesarelesssuitable forautomatedalgorithms.

Softwareteamsoftenhadtocreatetheir ownrulesforlightingcontrol,which neededtoworkgloballyforall populations,ages,moods,and activities.Advancedlightingcontrol essentiallyboilsdowntosettingNlamps tomeetMpeople’sneedswithL optimizationcriteria.Thesecriteria,like reducingglare,dependonlight distributionandhumanpreferences. Testingeverypossiblescenarioisn’t feasible,butcontrolalgorithmsoperate inrealtime,makingdecisionsinany situation,wellbeyondtestedlab conditions.

Lightingmodelsmustgobeyondsimple yes/noeffects.Theyneedtoquantify howmuchadeviationfromideallighting impactsperformance.SatisfyingM*L objectivesrequirescompromise,andit’s bestwhenalgorithmshandlethis.As newinsightsemerge,newcriteriacan beadded.I’madvocatingfor“forward models”thatpredicthowlightingwillbe appreciated,ratherthan“inverse models,”whichfocusonachievinga singleobjective.Forwardmodelscan evolveaslightingrequirementschange.

WithAI’srise,thequestioniswhetherit cansurpassrule-basedlightingcontrol andcreatebetterlightsettingsthan thosebuiltonperceptiontheory.Ifso, whathappenstothedecadesof research?Canthatknowledgebe embeddedinAI,orwillAIneedtostart fromscratch?

TobuildthesemodelsortrainAI, real-worlddataisneededfromactual officeswithrealpeopleinauthentic situations.WhileAIthrivesonbigdata, islightingexperiencedatatruly“big”? Peoplelikelywon’tappreciatebeing askedconstantlyforfeedbackontheir lightingexperience.“Pleaseratehow youfeltaboutthelightsdimminginthe lasthour”couldbecomeintrusive. Constantlyseekingfeedback,aswesee intoday’sworldwithsatisfaction surveys,feelsmorelikeasymptomof fearoffailurethanprogress.Isthis constantdemandforfeedbackreallythe bestwaytofuelAIforsmartlighting?

Lightingcontrolisn’taboutbigdata;it’s aboutthindata.Notlongago,theidea ofremovinglightswitchesandrelying entirelyonautomationseemed plausible.However,feedbackinterfaces arecrucial.Thegoalistominimizeuser interventionsasthesystemlearns.But relyingonuserfeedbackisrisky.People don’talwaysknowwhat’sbestforthem. Forexample,chronobiologyshowsthat bluelightintheeveningdisruptssleep, whileafternoonlightcanhelpstabilize ourcircadianrhythms.Askingpeople theirimmediatelightpreferencemaynot leadtohealthyoutcomes. ■

J-P.L.

DALIAllianceLightingAwards OpenswithNewCategories

for2024

www.dali-alliance.org/awards2024

DALIAlliance,theglobalindustryorganization forDALI,theinternationally-standardized protocolfordigitalcommunicationbetween lightingcontroldevices,announcesthatthe annualDALILightingAwardsareofficiallyopen for2024withanumberofnewcategories.

Thetraditionalapplicationcategorieshave beenconsolidatedtofiveawards:Residential, CommercialInterior,CommercialExterior, Industrial&Infrastructure,andHorticulture. Thisyear’sAwardswillalsoincludethe followinginnovationcategories:

• BestUseofD4i:Recognizinginnovative applicationsofDALID4itechnology, includingenhanceddatacommunication, energymanagement,andadvancedcontrol capabilities.

• BestEmergencyLightingIntegration: Celebratingsolutionsthatincorporate emergencylighting,ensuringsafety, reliability,andcompliancewithstandards duringemergencies.

• BestHumanCentricDesign:Honoring projectsthatprioritizehumanwell-beingin health,comfort,andproductivitythrough lighting.

• BestIntegrationintoOtherBuilding Systems:Highlightingprojectsthatexcelin integratinglightingdatawithotherbuilding systems,suchasHVAC,security,and energymanagement.

• InnovationinLighting:Recognizing cutting-edgetechnologiesand advancementsinlightingcontrolsolutions.

• SustainabilityandEnergyEfficiency: Highlightingprojectsthatexcelin sustainability,conservation,and environmentalimpact.

• SmartandConnectedLighting:Honoring advancementsinsmartlightingsystems, IoTintegration,andconnectedlighting solutions.

• Non-networkedLighting:Celebrating innovativeapplicationsinsmallor stand-alonespaces.

Thesenewcategoriesalignwiththegrowthof technologies,advancements,andinnovations thatarebeingadoptedbythelightingsector.

Thisyear’ssubmissionswillnolongerbe submittedtoaspecificcategory.Entrieswill beplacedbyjudgesintoapplicable categories,allowingthepossibilityofasingle projecttowinmultipleawards.

PaulDrosihn,generalmanagerofDALI Alliance,said:“Weareveryexcitedtolaunch thisyear’sDALILightingAwardswitha refreshedapproach.Weareconfidentthese changeswillmakeitmorestraightforwardfor thoseacrossthelightingindustrytoenter,and gainrecognitionfortheirwork.”

Theawardsentrydeadlineis7October2024. Formoreinformationandtoentertheawards, visit

https://www.dali-alliance.org/awards2024/

AbouttheDALIAlliance

TheDALIAllianceisanopen,global consortiumoflightingcompaniesthataimsto growthemarketforlighting-controlsolutions basedonDigitalAddressableLighting Interface(DALI)technology.TheDALIAlliance promotestheadoptionofDALI-2,D4i,and DALI+certificationprogramsandsupportsthe useofopen,interoperablelightingcontrol systems. ■

BuildingTechnologiesTrade FairswithaNew

Forward-lookingFocus

www.light-building.messefrankfurt.com

Thebuildingsectorisfacingmanymajor challenges:risingconstructioncostsanda shortageofskilledworkersarecollidingwith anurgentneedfornewhousing.

Simultaneously,theenergyandheating transition,nottomentiontherapidpaceof digitalization,arecreatingnewopportunities forasustainablefuture.MesseFrankfurthas respondedtothedynamicchallengesinthe marketwithanewlyformedmanagement teamforitsBuildingTechnologiesdivision.

JohannesMöller,whowaspreviously responsibleforLight+Building,hasbeen appointedGroupShowDirector,Building TechnologiesShows,withimmediateeffect. Overthelastfouryears,areallychallenging time,hesuccessfullymanagedtheworld’s leadingtradefairforlightingand building-servicestechnologywhile simultaneouslyexpandingitsinternational

network.Againstthisbackground,hehas beenresponsibleforthemanagementand strategicorientationoftheLight+Building, ISHandIntersecbrandssinceAugust2024.

HecontinuestoreporttoIris Jeglitza-Moshage,SeniorVicePresident Technology.Sheassumedresponsibilityfor thedivision14yearsagoandisalsoa memberoftheExecutiveBoardofMesse Frankfurt.“Möller’spromotionmeansshewill nowbeabletofocusmoreonhermanagerial duties,whilehermanyyearsofexpertisewill ensurethenecessarycontinuity.Bytakingthis step,wehavenotonlysettledthesuccession forthreeofourmostimportantbrandsatan earlystagebutalsoreinforcedthemanagerial resourcesneededforourBuilding TechnologiesIndustryCluster,”explainsIris Jeglitza-Moshage.Furthermore,sheexplains, “Wearedelightedthatwehavebeenableto findasuccessorwithinthecompany, especiallybecauseJohannesMöllerhas madeanimportantcontributiontothe successofourinternationalportfolioof BuildingTechnologytradefairsoverrecent years.Now,hewillbeabletoconcentratefully onthestrategicgrowthofthesebrandsin bothGermanyandabroad.”

JohannesMöllerbeganhiscareerinthe trade-fairindustryasagraduateexhibition, congressandeventmanagerinthesales departmentofProlight+Sound.Hethen spentfouryearsasthepersonalassistantto theCEOofMesseFrankfurtbeforeassuming responsibilityasDirectorofBrand ManagementandDevelopment,Technology, in2017.AftermanagingLight+Building, takingonoverallresponsibilityforthe Technologydivisionisthenextlogicalstep andrepresentsthecontinuationofhis previoussuccesses.

ISHwillremainundertheexperienced managementofStefanSeitz.Forthepast twelveyears,heandhisteamhavebeen planningandorganizingtheworld’sleading tradefairforHVACandwatereverytwoyears. ThemanagementteamfortheBuilding TechnologiesShowsGroupalsoincludes DominiqueEwert,whoisresponsibleforthe company’smarketing-communication activitiesinthefieldoftechnicaltradefairs.

From1October2024,SteffenLarbigwillbe responsibleforthedevelopmentofLight+ Building.Commentingonthenewmemberof themanagementteamatMesseFrankfurt,Ms Jeglitza-Moshagesays,“MrLarbigbringswith himextensiveinternationalsalesexpertise, experienceinkeyaccountmanagementanda wealthofideasforthefuturedirectionofLight +Building.”Thenextchapterinthe successfuldevelopmentofthebrandwillbe writteninclosecollaborationwiththehighly experiencedLight+Buildingteam (www.light-building.messefrankfurt.com). ■

LumiledsAddresses MicroLEDEfficiencyThrough EQEandDirectionality lumileds.com

LumiledshasrealizedsignificantExternal QuantumEfficiency(EQE)performancefor MicroLEDsinthepastyears.EQE,istheratio betweentheenergycontainedinthelight emittedfromtheLEDandtheenergyin electronsinjectedintothesemiconductor material.

However,formicroLEDs,anddisplay applicationsinparticular,EQEonitsownis notasufficientmeasureofperformance.To properlyassesstheefficiencyofamicroLED, onemustalsobeabletomeasurethe directionalityofthelight.Thedirectionalityof lightiscriticalformicroLEDdisplays,andfor

thisreason,displaysareoftencharacterized byRadiantorLuminousIntensity,asseen fromanangle.

“MostLEDsemitthemajorityoflightfromtheir topsurface.Thisisespeciallytrueforthinfilm LEDs.Whenweshrinkthesizeofthinfilm LEDstobecomemicroLEDs,the ‘side-emitting’surfacesbecomeasignificantly greaterportionoftheoveralllight-emitting surfaces,”explainedBrendanMoran, Lumileds’SeniorDirectorofMicroLED Development.

“Thethicknessofwhatwedescribedasathin filmforalargersizeLEDnowbecomes substantialrelativetothelengthandwidthof themicroLED.Thisisakeyreasonwhy microLEDsemitalargeportionoflightfrom theirsides,resultinginawideviewingangle distributionandareductionofintensity emittedfromthetopsurface.Fordisplay applications,evenhighEQEmicroLEDscan haverelativelylowon-axisintensity,”said Moran.

TheLumiledsR&Dteamhasnowdeveloped microLEDswithahighlydesirablelight distributionthatapproximatesLambertian distribution.Theteam’sinnovationresultsin brighterdisplaysthatconsumelessenergy.

BrendanMoranwillpresentonmicroLED advancesandefficienciesatthePlayNitride

MicroLEDTechnologyForumonSeptember 3rd,2024.

AboutLumileds LumiledsisagloballeaderinLEDand microLEDtechnology,innovation,and solutionsfortheautomotive,display, illumination,mobile,andothermarketswhere lightsourcesareessential.Ourapproximately 3,500employeesoperateinover15countries andpartnerwithourcustomerstodeliver neverbeforepossiblesolutionsforlighting, safety,andwell-being. ■

MetaroomandDIALuxtieup toEnhanceEfficiencyin3D ModellingforLightingDesign amrax.ai

MetaroombyAmrax,aspatial3Ddata capturecompany,hasannounceda partnershipwiththeworld’slargestlighting designsoftwareproviderDIALux.

Thetie-upwillenableuserstosend3Dscan datafromAmrax’sMetaroomsolutiondirectly toDIALux’splanningsoftware.Thisnew featurewillbeavailablefrommid-September withthereleaseofDIALuxevo13.Thisallows thefastcreationofpreciseanddetailedlight plansforeachroom.

Scans∗ canbemadeinamatterofminutes onanyAppleProdevicewithaLiDARsensor andtheninstantlyimportedintoDIALux.At thispoint,userscanexperimentwithscores ofdifferentfactorstofindthemostcost effective,aestheticallypleasing,functionaland sustainablelightingsolutionfortheirspace. ThepartnershipbetweenMetaroomand DIALuxaimstostreamlinethespatialdesign processforprofessionaldesignersand consequentlyhelptopowerinnovation, sustainabledesign,andlowercosts.

TheMetaroomappisanadvanced3D scanningapp,drivenbythepowerofAI, LiDAR(LightDetectionandRanging),and SLAM(SimultaneousLocalizationand Mapping)technologies.Thetoolenables professionalsinspatialplanningindustriesto envisionandredefinespaces.TheMetaroom solutionisaworkflowconsistingofMetaroom appforcaptureandMetaroomStudiofor optimizationbeforeexport.Throughthe Metaroomappuserscanscanroomsusing aniPhoneProoriPadPro*.Thesescansare thenuploadedtothecloud,generating true-to-scale3Dmodelswithinseconds. Userscanthenusethewebapplication, MetaroomStudio,toenrichthese3Dmodels withadditionalinformationbeforeexporting, ensuringproject-specificcustomizationand precision.

DIALuxistheglobalstandardinlightingdesign software,utilizedbyover750,000activeusers todesign,calculate,andvisualizelightingfor bothindoorandoutdoorareas.Featuringreal luminairesfromover412DIALuxmembers, userscancreateuniqueatmospheresand generatecomprehensiveproject documentation.Availablein26languages, DIALuxsupportsaworldwidenetworkof lightingprofessionalsandadherestotheopen BIMapproach.TheintegrationwithMetaroom isalsobasedonopenBIMandIFCstandards.

DIALalwaysprioritizestheneedsoflighting designersinitsfeaturedevelopment,aiming tostreamlinetheirworkflowsandsimplifytheir tasks.ByusingMetaroom,lightingdesigners cansavesignificanttimewhendesigningand placingluminaires.Projectscanbe convenientlydownloadedfromMetaroom StudioandimportedintoDIALux.The planningresultscanthenbeexportedasan IFCmodelfortheOpenBIMprocessorother programs,significantlyreducingtheworkload.

MartinHuber,CEOofAmrax,said:“Advances in3Dmodelling,softwareandAIare combiningtodemocratizedesign.Lighting designersandelectricalplannersnowhave accesstopowerfultoolsthatsignificantly enhanceefficiency,enablingthemtoserve morecustomersinlesstime.Thisisgoingto leadtoarevolutioninhowbuildingsare designedandhowweallinteractwithourbuilt environment.”Partnershipsbetweencutting edgesolutionslikeMetaroomandDIALuxare keytopoweringthischange.Bycreatingan extensiveecosystemoflightingdesign solutions,wewillsignificantlyimprove accessibility,reducecostsandbringspatial designtothemainstream.”

DieterPolle,CEOatDIALux,said:“Simply scantheroomwithyoursmartphoneandstart planningrightaway.Wouldn’tthatbe fantastic?ByintegratingMetaroominto DIALux,thisisnowpossible.The time-consumingtaskofconstructingthe geometrybeforestartingtheactuallighting designiseliminated.Martin’steamandtheir solutionhaveconvincedus.Theintegration followsourOpenBIMstrategytechnologically. Withthisintegration,we’vemadelifeabit easierforlightingdesigners.”

Over11.000Metaroomusers,includingkey playersinthelighting,wirelessplanningand AECindustries,haveregisteredthroughthe MetaroomappandjoinedtheAmraxB2B ecosystemdedicatedtospatialdesignand3D modelling.

∗Metaroomapp’sscanningfunctionalityis currentlycompatiblewithallLIDAR-enabled Appledevices(startingfromiPhone12Pro andiPadPro2020generationdevices). However,youcanviewordownloadshared 3Dmodelsdirectlyinanywebbrowser throughMetaroomStudio.Thedigitaltwinis

createdwiththeMetaroomappwithin minutesbyusingRGBanddepthsensors fromaniPhoneoriPadProtogetherwith deep-learningneuralnetworks.Theaccuracy ofLiDARsensorsoftheiPhone14Promodel isat0.5-1%.Therecognitionrangeis approximately5meters.

AboutAmrax

Amrax,thetechnologyplatformbehind Metaroom,wasfoundedin2020toexplore newwaystodigitizeanddesignspacesusing 3Dtechnology.Itoffersfast,inspiring,and user-friendlysolutionsforspaceplanningand interiordesign.Amrax’steamof25expertsin computervision,AI,softwaredevelopment, andmarketinguseinterdisciplinary collaborationandvirtualrealitytocreate groundbreakinginnovations.Headquartered inSalzburg,Austria,Amraxalsooperatesin ViennaandtheUSA.

AboutDIAL

DIAListhecompanybehindDIALux.The companyisbasedinLüdenscheid,thecityof light,andhasofficesinAmerica,Asiaand Italy.DIALhasbeenoperatinginthefieldof lightingdesignandbuildingautomationsince 1989.Thefocusisthedevelopmentof DIALuxevo.DIALbelievesthatgoodsoftware leadstogoodresults,sothecompany provideslightingdesignerswithallthetools theyneedtosimplifytheirwork. ■

GewissBecomesaMember ofLightingEurope

www.gewiss.com

Gewiss,aleadingcompanymanufacturing solutionsforhome&buildingautomation, energyprotectionanddistributionsystems, smartlightingande-mobilityhasjoined LightingEuropetogetherwithitsbrand focusedonLighting:PerformanceiNLighting |poweredbyGewiss.

“Itiswithgreatprideandanticipationthatwe announceourmembershipwith LightingEurope,theesteemedvoiceofthe lightingindustry.Ourcommitmentto innovation,sustainability,andexcellencein lightingdesignalignsperfectlywiththevalues andobjectivesofLightingEurope.

JoiningthisinfluentialBrussels-based organization,whichrepresents32companies andnationalassociations,marksasignificant milestoneinourcompany’sjourney.Weare eagertocollaboratewithourpeers,contribute totheshapingofindustrystandards,and advocateforpoliciesthatsupportthegrowth andevolutionofthelightingsector.

Webelievethatouruniqueinsightsand expertiseinthefieldoflightingwill complementthecollectiveknowledgeof LightingEurope’smembers.Together,wecan illuminatethepathtowardsabrighter,more efficient,andsustainablefutureforall.

Welookforwardtoactivelyparticipatinginthe dialogueandinitiativesthatdriveourindustry forward,andwearecommittedtobeinga proactivememberofthisdynamic community”,declaredAlfonsoD’Andretta, ManagingDirector-BusinessUnitLightingof Gewiss.

ElenaScaroni,SecretaryGeneralof

LightingEurope,warmlywelcomedGewissto theorganization,highlightingthecompany’s significantcontributionstothelightingmarket, standardsbodiesandEuropeantrade associations.“Gewiss’fullengagementwith LightingEuropefromdayonedemonstrates theircommitmenttotheorganization’s mission”,Scaroniadded.”Theirexpertisewill beinvaluableinourdiscussionson sustainableandconnectedlighting,andwe lookforwardtoworkingwiththem.Wealso appreciatetheirwillingnesstoadvocatefor betterenforcementtoensurethattheindustry operatesinafairregulatoryenvironment.This isakeyissueforthelightingindustry.

AboutGewiss

Developmentasaconstantinmanagementis thephilosophythathasguidedGEWISS’s choicesfromitsfoundationtotoday. Establishedmorethanfiftyyearsago, GEWISShasmadedevelopmentandthe researchforqualitytheprinciplesthathave guidedeveryactionandeverychoice.Guided bythevaluesofintegrity,excellenceand sustainability,GEWISSoffersinnovativeand scalablesolutionsforbuildings,industriesand infrastructures,capableofconnectingpeople andthingsandimprovingsafetyandqualityof life.Theconstantinvestmentsaimedat researchanddevelopment,thetrainingofall personnelandthestrengtheningofproduction facilitieshaveallowedGEWISStoestablish itselfasareferencepointforthemarketinthe productionofsolutionsandservicesforhome &buildingautomation,fortheprotectionand

energydistribution,fore-mobilityandsmart lighting.Theyear2023marksasignificant milestoneintheGroup’sgrowthjourneywith theacquisitionofPERFORMANCEiN LIGHTING,ahistoricleaderinthelighting industry.TheinclusionofthePERFORMANCE INLIGHTINGbrand”poweredbyGEWISS” hasallowedtheentireGrouptoexpandthe rangeofservicesavailabletothemarket throughplatformsynergiesandorganizations, offeringevenmoreintegratedsolutionsand technologies.Alltheproposalsaredesigned andproducedtomeeteverylightingneed, representingtheperfectsynthesisofaesthetic designandtechnicalperformance.The constantdrivetowardsinnovation,ahallmark oftheentireGroup’shistory,furtherpositions lightingsolutionsasasolidglobalreferencein theworldofdesignandarchitecture. ■

DALIAlliancetoHost

InauguralDALINorthAmerica SummitinNewYorkCity www.dali-alliance.org/events

TheDALIAlliance,theglobalindustry organizationforDALI,the internationally-standardizedprotocolfordigital communicationbetweenlightingcontrol devices,iselatedtoannouncethefirst-ever NorthAmericanDALISummit,settotake

placeonOctober30,2024,atthe MetropolitanPavilioninNewYorkCity.

TheSummitpromisesadynamicagenda featuringarangeoftopicssurrounding sustainability,smartbuildings,DALI-2 certification,D4iuse,andtheintegrationof DALIwithbuildingmanagementsystems.

Attendeeswillbenefitfromexpert-led presentations,interactiveworkshops,and paneldiscussionsdesignedtoaddressthe currentchallengesandopportunitieswithin thelightingindustry.

KeyHighlights:

ExploretheLatestDALITechnologiesand Applications:Gaininsightsintocutting-edge innovationsandpracticalimplementationsin thefieldofDALIlightingcontrol.

NetworkwithLeadingFiguresandPeers: Connectwithindustryexpertsandfellow professionalstoexchangeideasandbuild valuablerelationships.

EarnContinuingEducationUnits(CEUs): ParticipateinselectedsessionstoearnCEUs andenhanceyourprofessionaldevelopment. Tolearnmoreandtoregister,pleasevisit https://www.dali-alliance.org/events/dali-nor th-america-summit-2024.html

PaulDrosihn,generalmanagerforDALI Alliance,said:“Thisisthefirsttimewehave broughttheDALISummittoNorthAmerica, andweareexcitedtoconnectwithourpeers andfriendsintheindustrytoshareknowledge andbestpractices.Wehavelistenedtothe feedbackfromourmembersandweare committedtoopenupourknowledgebase andshareexpertiseonDALItechnology.The summitisakeypartofoureffortstoexpand theeducationalopportunitiesavailabletoour membersandotherstakeholders.Weare lookingforwardtosharingthisspecialevent withmembersofthelightingindustry.” ■ LUXEONHighPower3535

lumileds.com

We’dbestatingtheobviousifwesaidthat therearefew,ifany,one-sizefitsallsolutions inthisworld.Butthereyouhaveit.Starbucks provesthisinaclaimontheirwebsitethat therearemorethan170,000waysforpatrons

tocustomizetheirbeverages.Whilewe’venot countedallthewaystouseanLEDwitha 3535footprint,wesuspectthenumberis high.

SinceLumiledsintroduceditsfirst3535 packagein2013,theformathasbecomea de-factostandard,widelyadoptedinavariety ofoutdoor,industrial,andportable applicationsandsolutions.

RecognizingthatOEMsneeddifferentoptical, power,thermal,andefficiencyoptionsinthis format,Lumiledshasdevelopedthree high-powerLUXEONoptionsthatmakeit morestraightforwardforOEMstooffertiered performanceinasingleluminaire,offera rangeofluminaireswithdifferingvalue propositions,orreplaceanother3535LED withanyoneofLumileds’optionsasawayto expandanexistinglineand/orensureleading reliabilityandperformance.

WhenLumiledsundertakesthedevelopment ofanewLED,itdoessowithspecific applicationsinmind.Chipandpackage design,opticalandthermalperformance, outputandefficacyareallengineeredto producethebestin-applicationresults.Asa result,theopticalperformance,qualityoflight, coloroverangle,thermalcharacteristics, abilitytowithstandtheelements,output, efficacy,andmorecontributepositivelytothe finishedluminaire’sperformance.

TheLUXEON“3535”TeamWhenintroduced in2020,theLUXEONHL2Xfoundimmediate tractioninstreetandparkinglighting.Thanks toitshighlightoutput,superiorcolorover angle,andopticalefficiencythatmaximized thelumenoutputfortheapplication,the LUXEONHL2Ximmediatelyofferedan efficiencyadvantageattheluminairelevel. Withlifetestingatbothmildandsevere conditionscoveringmanythousandsofhours atitslaunch,LUXEONHL2Xincreasedthe confidencelevelforlongtermapplication colorandlightoutputstability.

Morerecently,Lumiledsintroducedboththe LUXEONHL4XandtheLUXEONHL4Z.Both LEDssharethe3535footprintwithLUXEON HL2Xandcanevenusethesameopticsin somecases,therebymakingitextremelyeasy toupgradealuminaire’sperformanceorto quicklycreatemultipleperformancelevelsfor aluminaire.

LUXEONHL4X,liketheLUXEONHL2Xisa domedemitterintendedforoutdoor,

industrial,andportableapplications.The LUXEONHL4Zisun-domedpowerLED,soit doesn’tsharetheopticalcharacteristicsofthe othertwo.Instead,itshinesinapplications thatrequireveryhighintensityandsuperior efficacy.Typically,engineersmustmakea tradeoffbetweenoptimizingopticaldesign andachievinghighefficacy.LUXEONHL4Z addressesthisdilemma.Atmaximumcurrent andinapplicationconditions,theundomed LEDdeliverstremendousintensity–over 1400lm–fromitssurfaceandcanoperateat animpressive189lm/W.

Perhapsthesimplestexampleofhowthese threeLEDscansupportasingleapplicationis thecaseofatorchorflashlight.Inthe examplebelowitiseasytoseehowthe performanceofanidenticaltorchandreflector canresultinthreedistinctperformance envelopes.Dependingonthedesired performance,costandmarkettargets,a singlesolutiondesigncouldbesupportedby thisteamofLEDs.

Certainly,apowerfulcasefortheuseofthis trioofLEDsintorchlightingiseasytomake. Thesignificantadvantagesthisteamoffersto OEMs,andultimatelyend-usecustomers,is inthemorecomplicatedandnuancedworld ofhigh-powerlightinginstadiums,on roadways,pathways,andindustriallighting suchashighandlow-bayenvironments.In usecaseslikethese,theabilitytoutilizeLEDs withacommonfootprintandachieveoptimal applicationperformancecanlowerdesignand manufacturingcostsandspeedtimeto market.

Lumiledshigh-powerLEDsthatsharethe 3535footprintareessentially“starters”, top-notchoptionsthatperformindividually andthatprovideOEMstheflexibilityto addressopportunitiesthatleadtogreater successwiththeirclients. ■

www.acuitybrands.com

AcuityBrands,Inc.(NYSE:AYI)announced thatsevenAcuityBrandslightingand componentssolutionswereselectedforthe 2024IlluminatingEngineeringSociety(IES) ProgressReport,whichshowcasestheyear’s mostsignificantadvancementsintheartand scienceoflighting.Selectionsweremadeby animpartialcommitteethatevaluated submissionsbasedonuniqueness, innovation,andsignificancetothelighting industry.

2024IESProgressReportinclusions:

A-Light™Linoluminaire,IVO™Shallow RecessedDownlightfromGotham®Lighting, Hydrel®TierraIngradeFamily,IOTAILD SeriesEmergencyDrivers,Juno®2”Canless WaferDownlights,andtheLithonia®FRAME LEDLay-infromLithoniaLighting®.

A-LightLinoisavailablein2.16”and3” apertures,andthesmallprofilehousingand novisiblehardwareensurethatthefixture subtlyintegratesintoavarietyofinteriorand exteriorenvironments.WithanIP66rating, Linoluminairesareparticularlywell-suitedfor outdoorapplicationswithharsherweather conditions.Designerscanmixandmatch fromnumeroussuspendedorsurface mountingstomaintainaconsistentdesign aesthetic.Suspendedmountingsinclude catenaryorpendantstem.Ceiling,wall, channelormullionblockcanbeselectedfor surfacemountings.Directilluminationis availablewithbatwing,flatbladelouver,HE Tech™,wallgrazerorasymmetricdistribution types,eachmeetingspecificlightingneeds. Designersmaychooseindirectilluminationfor

themullionblockmountingoption.Available inupto8-footstandardlengths,luminaires canbetrimmedtospecificsizesinincrements of1/8inch.LuminairesmaybejoinedwithL-, T-,orX-cornersforcreativepatterns. Sustainabilityisakeyelementofthedesign, includingfixturesthatcontain60%recycled aluminumextrusions.Linoluminairesare enabledwiththenLight®networkcontrol system.

CycloneCrosswalkOpticssolutiontakesinto accountthetwomaincontributingfactorsto pedestrianvisibility,includingcontrastand verticalilluminance.Withasymmetrical forwardandasymmetricalrightsidelight distribution,theopticsprovideahighpositive contrastthatmakepedestrianslookbrighter thanthebackground.Theyalsoenhance verticalandhorizontalilluminancetohelp motoristsclearlyandeffectivelydetectthe crosswalkandthepedestrianwellinadvance. Theyaredesignedbasedontheguidancein IESRP-8;RecommendedPractice:Lighting RoadwayandParkingFacilities,withparticular attentionpaidtotherecommendations focusedonpedestriancrosswalks.Theyare availableinlumenpackagesrangingfrom 3,100lmto11,600lmandallversionsare IP66ratedforharshweather.

GothamIVOShallowRecessedDownlight addressesspatiallimitations,fittinginto spacesasshallowas2inches,while deliveringexceptionalperformance.Boasting

upto3000lumensfroma4-inchapertureand upto5000lumensfroma6-inchapertureand deliversupto120lumensperwatt.Designed forfield-serviceability,thedownlightfeatures interchangeabletrimsandopticsthatcanbe effortlesslyservicedfrombelowtheceiling withasimpletwistandlockmechanism.The IVOdownlight’sdesignuses17%lesssteel, 44%lessaluminum,and28%lessplastic comparedtostandarddownlights.Perfect colorconsistencyisachievedwitha0.5 MacAdamellipsefromfixturetofixture. Proprietaryopticscoupledwithanadvanced lightengineandBoundingRay™Optical Designdeliversatrueuniformed,batwing distributionforsmoothilluminationanda comfortableexperienceforoccupantsinthe space.Theyoffercolortemperatureoptions from2700Kto5000K.Thedownlight supportsuniversaldimmingto1%through 0-10V,120VTriac,andELVprotocols. IntegrationwithnLight®wiredorwireless lightingcontrolsfurtherenhancescontrol options.

HydrelTierraoffershigherdeliveredlumens, morecolortemperatures,andmoreoptions thantheaverageingrade-inacompact design.Withonly4.4”and6.38”diameters, theTierraseriesisaningradethatcombines impactandcorrosion-resistantmaterials, optimalbeamcontrolandsuperior performance.Deliversexceptionaluniformity andon-targetillumination.Itsprecisionoptical systemoffersexcellentcontrolledbeam angles.Modulardesignallowsforeasy

installation,driverreplacement,andlight sourceupdatesastechnologyadvances. Tierraincorporatesinnovativesealing capabilities,superiormaterials,and long-lastingfinishes,promisingdecadesof usewithminimalmaintenance.Itsstructural integrityisunmatched.

IOTAILDSeriesEmergencyDriverisaUL

ListedLEDemergencydriverthatallowsthe sameLEDfixturetobeusedforbothnormal andemergencyoperation.Intheeventofa powerfailure,theILD10switchespowerfrom thenormalACDriverandoperatesthefixture for90minutesintheemergencymodefrom theunit’sbatterysupply.The Quick-Disconnectwiringconnectorsprovide installationflexibilityandoptimization,allowing forsnap-infieldreplacement.Theunit containsabattery,charger,andconverter circuitinanarrowprofileenclosurefor installationwithinthechannelspaceor wireway.TheILD10willoperateanLEDload at10wattswithconstantpoweratarated outputvoltageof10V-55V.TheConstant PowerdesignoftheILD10maintainsthe outputwattagetotheLEDarrayevenasthe systemvoltagediminishes,providinga consistentilluminationlevelforthefull 90-minuteruntime.Itfeatureslithiumbattery technologyforsignificantlydecreasedform factor,automaticmonthlyandannual

self-testingcapability,andACActivatebattery activationcircuitry.

Juno2”CanlessWaferDownlighthasan innovative,slimdesignthatinstallsquicklyand easilyintoaslittleas3”ofplenumallowingfor ittofitintoceilingspaceswheremost traditionalrecessedhousingsdonot.No housingrequiredtoinstall.Onceinstalled,the Waferprovidesanall-in-onedesignfeaturing switchablewhitecolortemperatureand adjustablelumenoutputtechnology.This technologygivesdistributors,contractorsand homeownerstheultimateinflexibilityby providingtheequivalentof15staticfixturesin one.Thesetechnologiesarecontrolledby switcheslocateddirectlyonthefixture.Simply toggleeachswitchtothedesiredsettings: 2700K,3000K,3500K,4000K,or5000Kfor colortemperatureadjustmentandlow, medium,highforlumenadjustment.

LithonaFRAMEbyLithoniaLightingoffersa modern,upscaleaestheticwithfunctionality andperformancetomatch.Attheheartofthe FRAMEdesignisthe‘snap’together assemblywhichprovidesunrivaledvaluein shipping,storageandinstallationcosts. FeaturingSwitchablecolortemperatureand adjustablelumentechnology,theFRAME allowstheusertofinetunethelookandfeelof theirspace.TheFRAMEisdesignedwiththe latestopticaltechnologytoprovidethesame

efficiencyandoutputasatraditionalLEDflat Panel,forafractionoftheweightandcost.

AboutAcuityBrands

AcuityBrands,Inc.(NYSE:AYI)isa market-leadingindustrialtechnology company.Weusetechnologytosolve problemsinspaces,light,andmorethingsto come.Throughourtwobusinesssegments, AcuityBrandsLightingandLightingControls (ABL)andtheIntelligentSpacesGroup(ISG), wedesign,manufacture,andbringtomarket productsandservicesthatmakeavaluable differenceinpeople’slives.

Weachievegrowththroughthedevelopment ofinnovativenewproductsandservices, includinglighting,lightingcontrols,building managementsolutions,andlocation-aware applications.AcuityBrands,Inc.isbasedin Atlanta,Georgia,withoperationsacrossNorth America,Europe,andAsia.TheCompanyis poweredbymorethan12,000dedicatedand talentedassociates.

Alltrademarksreferencedarepropertyoftheir respectiveowners. ■

BartenbachGmbH

AnnouncesNewLeadership withHelmutGuggenbichleras ManagingDirector

www.bartenbach.com

HelmutGuggenbichlerwasappointedasthe newManagingDirector,bringingwithhima freshperspectiveandextensiveexperiencein daylightandartificiallightingdesign.Heis well-positionedtoleadBartenbachintothe future.

BartenbachGmbHrecentlyannouncedthe departureofitsesteemedManagingDirector, MatthiasSporer,followingthreeyearsof dedicatedcollaboration.Hisinvaluable contributionsandcommitmentplayedakey roleinshapingBartenbachintothecompany itistoday.

TheleadershipteamatBartenbachGmbH underwentastrategicrealignment,with HelmutGuggenbichlerjoiningforceswith DanielFöger,HeadofResearchand Development,andChristianJenewein,Head ofFinanceandAdministration.Together,they

continuedtodriveinnovationandupholdthe company’shighstandardsofquality.

HelmutGuggenbichlerviewshisnewroleas anexcitingchallengeandlookedforwardto exploringnewavenueswhilecontinuing Bartenbach’ssuccessstory.Thecompany remainsfocusedonitsvision:creatingvisibly betterlightforpeopleandtheenvironment.

BartenbachGmbHbeganthisnewchapter, anticipatingsuccessfulprojectsin collaborationwithitspartners. ■

YongjiangLaboratoryOrders

ReactiveIonBeamTrimming EquipmentfromsciaSystems

www.scia-systems.com

ThesciaTrim200systemprovidesprecise surfacecorrectioninfilmandwafermaterials usingionbeamtrimming.Thefilmthickness uniformitycanbeadjustedupto0.1nm.

sciaSystemsGmbH,theindustryleaderin advancedionbeamandplasmaprocess equipmentformicroelectronics,MEMS,and precisionopticsindustries,announcedthat YongjiangLaboratory(Y-LAB),anon-profit researchandinnovationcenter,establishedin

2021inZhejiangprovince,China,has purchasedasciaTrim200system.

High-PrecisionSurfaceCorrectionwithscia Trim200ThesciaTrim200guarantees high-precisionfilmthicknesstrimminginwafer processing.Typicalapplicationsarefrequency andthicknesstrimminginthemanufacturing ofacoustic-electricaldevicesandfilterslike bulk(BAW)orsurfaceacousticwave(SAW) filters,localizedpoletrimmingofthinfilmhead (TFH)applications,anddimensionalcorrection ofMEMSstructures.

Designedforhigh-volumeproductionand R&Dapplications,thesystemisequippedwith astandardsemiconductorcassettehandling robotthataccommodateswafersupto200 mmindiameter.

Thefilmtrimmingisperformedbyafocused broadionbeamwithasufficientlysmallfocal point.Theionbeamisdirectedtothe substratesurface,causingaphysical sputteringeffecttoremovematerial.During

trimming,thewafergetsmovedinfrontofthe ionsourcebyanx-/y-stage.

Ametrologysystemdetectstheexact frequencytopographymapofeachwaferarea andconvertsthistopographymapintoa coatingthicknessmap.Basedonthat,the thicknessofthecoatingthatneedstobe trimmediscalculated.Afterward,theinternal controlsoftwareofsciaSystemcalculatesthe correspondingdwelltimemapandfollowsthe velocityscanprofilesforthetrimmingprocess. Byadjustingthelocaldwelltimeoftheion beamatspecificpositions,thesystemcan controlthelocalremovalandetch non-uniformities,resultinginanimpressive homogeneousfilm.

Whileionbeamtrimmingisdonewithnoble gaseslikeArgon,reactivegasescanalsobe usedforcomplexdevicestructurestoincrease selectivity(reactiveionbeamtrimming,RIBT).

“WeareproudthatY-Labhasoptedforion beamequipmentprovidedbysciaSystems foritslaboratory.ThesciaTrim200offersa highdegreeofvariabilityandisagoodbasis forfuture-orientedinnovationsandapplied researchthankstoitsmaximumflexibilityin processingwafermaterialswithoutany restrictionsanditsabilitytoadjustthefilm thicknessuniformitydowntotheatomlevelof 0.1nm.”statedDr.MichaelZeuner,CEOof sciaSystems.

MoreinformationonthesciaTrim200system canbefoundat www.scia-systems.com/pro ducts/ion-beam-trimming/scia-trim-200

AboutsciaSystemsGmbH Foundedin2013,sciaSystemsisthe technologyleaderinthin-filmprocess equipmentbasedonadvancedionbeamand plasmatechnologies.Thesystemsareused forcoating,etching,andcleaningprocesses withnanometeraccuracyandhavebeen successfullyimplementedinvarioushigh-tech industriesworldwide,including microelectronics,MEMS,andprecisionoptics industries. ■

ProminentSouthernCalifornia LightingRepsMergetoForm

LINXLIGHTING&CONTROLS

westernlightingandenergycontrols.com/ WesternLighting&EnergyControlsand Forman&Associateshaveannouncedthe mergerofbothcompaniestoformoneofthe largestlightingrepagenciesintheSouthern CaliforniaRegion.

Currently,WesternLighting&EnergyControls servesastherepresentativefor90+lighting brandsacrossSouthernCaliforniaandisbest knownforrepresentingLutron.Lutronisthe marketleaderinhigh-qualitylighting,controls andautomatedwindowsystems.Together, WesternandLutronhaveadvancedthe technologyoflightingcontrolinSouthern Californiawhilemaintainingtopmarket positionbyfocusingonexceptionalservice, qualityanddesign.

Formanpresentlyservesastherepresentative for100+lightingbrandsinSouthern&Central California,Signifyisitsflagshipmanufacturer, witharobustportfolioofprofessionallighting solutionsforcommercial,industrialand entertainmentprojects,inadditiontostock andflowdemand.Signify’sGenlyteSolutions portfolioencompasseslightingcontrolsand IoTplatformbrands,PhilipsDynaliteand Interact;globalarchitecturallightingbrand ColorKinetics;PhilipsLEDlamps,EvoKitsand Advanceelectronics;aswellasindoor luminairebrandsAlkco,Chloride,Day-Brite, LedaliteandLightolier;andoutdoorluminaire brandsGardco,Hadco,Lumec,andStonco. FormanalsorepresentsSignify’s

entertainmentlightingbrandVari-Liteand emergencylightingbrandBodine.

Bymergingtheextensiveresourcesoftwoof SouthernCalifornia’stoplightingrepagencies, thetwocompaniesareforgingapowerful connectiontocreateanunparalleledsynergy inthemarketplace.Thenewcompany, rebrandedasLINXLighting+Controls,will providecomprehensivesolutionsforlighting andcontrols,alongwithdedicatedcustomer service&fieldservicesupportacrossall aspectsofelectrical,lighting,andcontrol requirementsforanyproject,linkingour customers(specifier,channel,installer, end-user)togetherinsuccess.

Thisstrategicexpansionreflectsa commitmenttotheSouthernCalifornia LightingCommunityaswellastoallour valuedmanufacturingpartners.Withofficesin VanNuys,CostaMesa,andSanDiego,the newcompanyispositionedtoservicethe region.

AboutWesternLighting&EnergyControls: https://westernlightingandenergycontrols.com

Establishedin1996,WesternLighting& EnergyControlsrepresentstopmanufacturers acrossSouthernCalifornia.Thecompanyis committedtothoroughunderstandingin manufacturerprocessing,development,and technicalproductsupport. ■

ZhagaConsortiumandDALI AlliancetoExhibitat2024 StreetandAreaLighting Conference

www.dali-alliance.org

TheZhagaConsortiumandtheDALIAlliance arepleasedtoannouncethattheywillbe exhibitinginadjacentboothsattheupcoming 2024IESStreetandAreaLightingConference (SALC),settotakeplace22-25September, 2024inAtlanta,GA.Thecollaboration betweentwooftheleadingorganizationsin thegloballightingindustryhighlightstheir sharedcommitmentandsynergytoadvancing thefutureofstreetandarealightingthrough innovation,interoperability,andsustainability.

TheZhagaConsortium,aglobal lighting-industryorganizationwithover600

members,will,atthisyear’sconference, emphasizethetransformativepotentialofthe Zhaga-D4istandard,whichissettingnew benchmarksforsmart,energy-efficient,and future-proofoutdoorlightingsolutions.

OneofthekeythemesforZhagaattheevent willbeextendingtheusefullifeofstreetlights throughcircularlightingpractices.This includespromotingmodularluminairedesigns thatallowforeasyupgrades,repairs, replacements,andservicing—critical elementsforachievinggreatersustainabilityin urbanenvironments.

VisitorstotheZhagabooth(#606)willhave theopportunitytoexploretheBook18 platform,anecosystemofinteroperable componentsforoutdoorlightingthat showcasesthepoweroftheZhagastandard indeliveringsmartandfuture-prooflighting solutions.Attendeesareencouragedtovisit theZhagaboothtoseelivedemonstrationsof theBook18platformandtoengagewith Zhagaexperts,whowillbeonhandtodiscuss detailsaroundtheplatformandproduct certification.

TheDALIAlliance,theglobalindustry organizationforDALI,theinternationally standardizedprotocolfordigital communicationbetweenlightingcontrol devices,willusethe2024IESStreetandArea LightingConferencetodemonstrateits innovationsinsmartstreetandarealighting. DALIAlliancememberswillshowcase solutionsthathighlighttheinteroperability, scalability,andsustainabilityofDALI-based lightingsystems.TheDALI-2andD4i standards,whicharepivotalinthe advancementofsmart,energy-efficientstreet lighting,willbeattheforefrontofthese demonstrations.

KeyhighlightsfortheDALIAlliancebooth (#608)atSALC2024willincludelive demonstrationsofaD4isystem,whichoffer enhancedinteroperabilityandconnectivityfor streetlightingapplications.Additionally,the DALIAlliancewillpresenttheadvantagesof D4iandZhaga-D4icertificationforintelligent, data-richluminairesthatenableadvanced assetmanagementandpredictive maintenance,contributingtothelong-term sustainabilityofurbanlightinginfrastructures.

AttendeesareencouragedtovisitZhaga (#606)andDALIAlliance(#608)boothstosee livedemonstrations,learnmoreaboutour innovations,andengagewithourexpertsto discoverhowZhagaandtheDALIAllianceare shapingthefutureofstreetandarea lighting. ■

GlobalLeadershipinLighting–

CIE’sRoleinDrivingTechnology, TonyBERGEN,Vice-President TechnicalofCIE

TonyBERGEN

“Werealizethatlightissomuchmore thanjusthowweseethings:thatit influencesprocessesconnected fundamentallytoourbehavior, physiology,healthandwellbeing, includingcircadianregulation.Allof theseprocesseshappenthroughout thebody,inparallel,atonce,andso weusethetermintegrativelighting.”

Inthiscompellinginterview,TonyBergen,VicePresidentTechnicalofthe InternationalCommissiononIllumination(CIE)andChairoftheTechnical ManagementBoard(TMB),shareshisremarkablecareerjourneyand pivotalroleinshapinggloballightingstandards.Asaphysicistandleader inphotometricandradiometricmeasurement,Tonyprovidespowerful insightsintotheevolvinglandscapeoflightingtechnology.Hediscusses theCIE’srestructuring,theintegrationofcutting-edgetrendssuchasAI, integrativelighting,andsustainability,andthechallengesofsteeringthe futureofillumination.Thisconversationisamust-readforanyone investedinthefutureoflightinginnovation.

https://cie.co.at

LEDprofessional: Tony,thankyoufor theopportunitytoconductthisinterviewwithyou.Firstofall,wewould beinterestedinhearingaboutyour careerjourneyandhowyouultimately becametheVPTechnicalofCIEand chairoftheCIE’sTechnicalManagementBoard(TMB).

TonyBERGEN: Thankyou,Siegfried,for theinterview.

Iamaphysicistanddirectlyinvolved intwointer-relatedcompanies,both basedinMelbourne,Australia.PhotometricSolutionsInternational,inwhich IamTechnicalDirector,isamanufacturerofcustomtestingandmeasurementequipment.Throughthiscompany Ihaveinstalledequipmentinallcontinentsaroundtheworld1.Inparallel,I amManagingDirectoroftheAustralian PhotometryandRadiometryLaboratory,anaccreditedpublictestingand calibrationlaboratoryandconsultancy service.Additionally,withsomepartners, wearecurrentlyforminganewcompany toworkonminiaturizedsensorsforpersonaldosimetryandlightingcontrols. Alloftheseroleshavegivenmeagood groundinginmeasurementandlaboratorypractice.

IstartedinCIEattheBeijingSession in2007andbecameactivelyinvolved inCIEDivision2(D2),whichdealswith thephysicalmeasurementoflightand radiation.IhaveservedasD2Secretary (2013to2019)andD2Director(2019 to2023)and,asyoumentioned,Iam presentlyCIEVice-PresidentTechnical.I alsochairCIETC2-78,whichdealswith

1Well,almostall,stilltryingtogettoAntarctica.

goniophotometry,andTC2-77,whichis aD2socialcommittee.

IhavealsoservedasAustralia’sD2DivisionMembersince2010andwasPresidentofCIEAustraliafrom2015until earlierthisyear.

LEDprofessional: AstheVice-President TechnicaloftheCIEandtheChairof theTechnicalManagementBoard (TMB),weareinterestedinlearning abouttheresponsibilitiestheseroles entailandhowthetechnicalwork ismanagedbytheTMB.Howisthe TMBintegratedwithintheCIEstructures?

TonyBERGEN: TheTMBisarelatively newentitywithintheCIE:established lastyearwhentheupperlevelsofgovernanceoftheCIEhadarestructure. Previously,therewastheCIEBoardof Administration,whichincludedthePresident,Vice-Presidents(withandwithout portfolio),Treasurer,Secretary,thesix DivisionDirectorsandtheCIEGeneral Secretary.FromSeptember2023,this waseffectivelysplitintotwoseparateentities:

• TheGoverningBoard(GB),which consistsofthePresident(chair),VicePresidents(withportfolio),general membersandtheCIESecretaryGeneral;and

• TheTechnicalManagementBoard (TMB),whichconsistsoftheVicePresidentTechnical(chair),VicePresidentStandards,thesixDivision Directors,theCIESecretaryGeneral andtheCIETechnicalManager.

TheGBisresponsibleforoverallgovernance,strategicplanning,financial management,andexternalrelations. TheTMBisresponsibleforthescientificandstandardsworkprogramofthe CIE,includingapprovalofnewTechnicalCommittees(TCs)andTCchairs, reviewandapprovalofpublications,organizingofplenaryscientificevents,etc. HavingbeenaDivisionDirectorinthe previousBoardofAdministration,Ican saythatIthinkthatthisisaverypositive changeastheTMBmemberscanfocus onthescientificaspectoftheorganizationwithoutneedingtobeinvolvedwith decisionsregardingfinancials,policies, strategy,etc.

LEDprofessional: Beforewedelve intotheindividualtechnologies,it wouldbeimportanttounderstandthe scientificdivisionswithintheCIEand thetopicstheyeachaddress.Could youprovideabroadoverviewofthese thematicareas?

TonyBERGEN: Therearesixscientific DivisionsoftheCIE:2

• Division1:VisionandColor

• Division2:PhysicalMeasurementof LightandRadiation

• Division3:InteriorEnvironmentand LightingDesign

• Division4:TransportationandExterior Applications

• Division6:PhotobiologyandPhotochemistry

• Division8:ImageTechnology

EachDivisionisledbyaDivisionMan-

2Formoredetailssee: https://cie.co.at/technical-wor k/divisions

agementTeamconsistingofaDirector, Secretary,Editor,andAssociateDirectors.ThescientificworkoftheDivision isperformedbyTechnicalCommittees (TCs),whichwritetheCIEpublications undertheleadershipoftheTCChairs, andReporterships,ledbyareporter, whichwritea(usuallyinternal)reporton atopicofrelevancetotheDivisionand oftenformingtheforerunnerofafuture TC.TherearealsoLiaisonRepresentativesandDivisionCorrespondentswith other(external)organizations.

Butmostimportantly,thescientificprogramoftheDivisionanditspublications arecommentedandapprovedbyrepresentativesofeachoftheCIE’sNational Committees.ThisunderpinstheinternationalnatureoftheCIE:thatwehavea trulyglobalbreadthacrossallsixcontinents.

LEDprofessional: WehadtheopportunitytointerviewJenniferVeitch, PresidentoftheCIE,whereweparticularlyfocusedonthenewresearch strategyoftheCIE.Whichelements ofthisstrategybringsignificantchanges andalsoinfluencecollaborationwith researchinstitutes?

TonyBERGEN: ThankyoufortheinterviewwithJennifer,whichwasan excellentread.Theresearchstrategy (Table 1)itselfisn’tnew,butitdidundergoasubstantialrevisionandreformattinglastyear.Ithastwooverarching themes: Digitaltransformationofmetrology,science,andindustry;and Towards inclusive,equitablelighting;aswellas sixtopicalthemescoveringareassuch asmeasurement,health,agricultureand aquaculture,photobiologyandcolor. Significantly,eachofthesetopicsand themesarelinkedtotheUnitedNations 2030SustainableDevelopmentGoals (SDGs),andsurprisinglywhenwriting thedocumentwefoundthatlightand lightingtouches12ofthe17SDGs!It’s agreatreadforanyoneinterestedinlight andlightingandcanbedownloaded freely.3

Thepurposeoftheresearchstrategy istoinspireresearcherstoinvestigate importanttopicstoshapethenextgenerationofguidanceandstandards.Particularlyimportantistheemphasison diversityandinclusiveness,whichisa themethatpermeatesthestrategy.We

3CIE’sResearchStrategy: https://cie.co.at/research -strategy

alsosupportresearchfundingapplicationsthatalignwithourscopeandpriorities,andcanissueLettersofSupportfor relevantresearchendeavorscontributingtotheongoingworkofCIE–further detailscanbefoundatthelinktotheresearchstrategygivenabove.

LEDprofessional: Nowwewouldlike toaddressafewcontentareasthat, inourview,arehighlyrelevantand impactfulforboththeindustryand theplanningsector.Couldyouname thekeytrendsineachoftheseareasfromatechnologicalperspective andexplainwhattheCIEiscurrently undertakinginthesefields,namely: QualityofLight,AestheticandArchitecturalLighting;IntegrativeLighting; SustainabilityandEnergyEfficiency; LightingIntelligencewithSmartLighting,IoT,BMS,andControls;and WirelesswithLi-Fi,WirelessPower Transfer?

TonyBERGEN: LightingqualityisfundamentaltotheworkoftheCIEand encompassesindividualwell-being,economicsandarchitecture.Twoofour Divisionsinparticular(Division3and4) incorporateaspectsoflightingquality andaestheticsintomanyaspectsoftheir work.Lightingisnotjustconcernedwith theabilitytosee.Itsatisfiesvisualneeds andcreatesexperiencesthatsitatthe verycoreofourevolutionaryjourney. Evenbeforemoderntechnology,we neededbasicssuchasheat,lightand security.Astechnologyhasadvanced,

amongthethingsthathavenotchanged arethesevisualexperiencesthathumanitytookforgrantedwhendaylight, firelight,andmoonlightweretheprimary lightsources.

Themorethatwestudythehumanvisionsystem,themorethatwerealize thatlightissomuchmorethanjusthow weseethings:thatitinfluencesprocessesconnectedfundamentallytoour behavior,physiology,healthandwellbeing,includingcircadianregulation.Allof theseprocesseshappenthroughoutthe body,inparallel,atonce,andsoweuse thetermintegrativelighting4 todescribe this.Wehavehadseveralpublications onthistopic,andourrecentlyupdated positionstatementonintegrativelighting, recommendingproperlightattheproper time,freelydownloadablefromtheCIE website5,providesmoreinformationon this.Notethattheterm“humancentric lighting”isalsousedtodescribeasimilar meaningasintegrativelighting,butitis notsufficientlyprecise.

Ithinkthatsustainabilityandenergyefficiencyareintricatelylinkedtolighting qualitywhichwediscussedabove.This topicwasalsodiscussedinyourearlierinterviewwithourVice-President StandardsPeterThorns,andheemphasizedtheneedtonotgettoofocused onjusttheoneaspectoflightingatthe

4IntegrativeLighting: https://cie.co.at/eilvterm/17-2 9-028

5Updatedpositionstatementonintegrativelighting: https://cie.co.at/publications/cie-position-statements

*Integrativelightingforpeople

*Ecologicallyrespectful,high-qualityexteriorlighting

*Fundamentalsofphotobiologyforagricultureandaquaculture

*Enablingtheapplicationofsafe&beneficialopticalradiation

detrimentofallothers.Itispossibleto makealightinginstallationveryefficient sothatitmeetsthestandardsandminimizesenergyuse,butifitcreatesalit spacewhichisnotpleasanttoworkin orwhichdoesnottakeintoaccountthe integrativelightingaspectsthenitisnot necessarilyfulfillingitspurpose.

LEDprofessional: Whatroledoesartificialintelligencecurrentlyplay,or willitplayinthefuture,inthelighting sectorandlightingtechnology?

TonyBERGEN: Ithinkthatitisvery clearthatAIalreadyplaysaroleinthe lightingsector.Lightingdesignersuse AItooptimizetheirdesignsandsave time.ResearchersareusingAItoanalyzelargeamountsofdatatoachieve greaterinsights.

AIwillbeusedinthefuturetocontrol buildingsandacceptmultipleinputsfrom weatherdata,occupancydata,task data(probablylinkedtoareasinuseand peoplepresent)tocontrolbuildingand publicservices.Thiswillallowbuildings andtheurbanenvironmentto“plan”for needsasopposedtoreactingtocurrent events,therebyincreasingefficiency.

Inmyownfieldofmeasurement,there aredevicesavailablewhichusecheap sensorswithlimitedproperties,machine learning,andtablesofdataproduced frommorecomplexandhigherquality measurementequipmenttoproduce asynthesizedmeasurementresult.It’s notalwaysclearwhetherthisisactuallymeasurementor“guesswork”,andit makesaspectssuchascalibration,measurementuncertaintyanddocumented traceabilityfarmorecomplicated!

AnotherapplicationofAIistheconcept of“digitaltwins”,whicharelikedigital replicationsofareal-lifeobjectorprocess.TherearealreadyprojectslookingatmodellingproductssuchasLED packagesandluminairestopredicthow theywilloperateintherealworld.6 In termsofpeople,thiscouldinvolvemappinganindividual’svisionsystemand theircolorperception.

LEDprofessional: Itisevidentthat lightingexpertsfrombothindustry anddesignshouldengagewiththe resultsoftheCIE.Thisfoundational workisessentialforanydevelopment inthelightingsector.Howcaninter-

6DigitalTwinprojectexample: https://ai-twilight.eu/

estedpartiesstayinformedaboutthe results?Wherecantheyaccessthe publications,andhowcantheyparticipatetoensuretheydon’tmissany relevantfindings?

TonyBERGEN: CIEisrecognizedby otherinternationalstandardizingbodies suchasISOandIECasbeingresponsibleforproducingfundamentalstandards inourfields.Expertsarewelcometojoin ourtechnicalcommitteestotakepart inthewritingofourpublications,which includesnotonlystandardsbutalso technicalreports(whichprovidemore backgroundinformationthanstandards) andtechnicalnotes(whicharemorebrief documentsusuallywrittentoaddressan urgenttopic).

Buttherearealsosituationswhereresearchonemergingtopicsisnotestablishedenoughtosupportthecreation ofaTCtowriteaCIEpublication.While wedon’tactivelyundertakeresearchas suchourselves,wedocreateresearch foratocoordinateworkonsuchtopics. ThesecanbefoundontheCIEwebsite7,andwehighlyrecommendthat researchersapplytojoinaresearchforumtocontributetotheknowledgeso thatnewTCscanthenwritethepublicationsforguidanceorstandardization purposes.

CIEpublicationsareavailableforpurchasethroughtheCIEwebsite,andwe alsohavenewslettersinwhichwepublicizenewpublications,eventsandother news.CIEalsohasatranslationpolicy whichallowsourNationalCommittees toleadtranslationsofourpublications intootherlanguages,andhencemanyof ourpublicationsareavailableinmultiple languages.

AnyonecansignuptoreceivethequarterlyCIENewslettertostayinformed aboutnewTCsseekingexperts,new publications,andotherCIEupdates.8

LEDprofessional: Nextyear,theCIE MidtermMeetingwilltakeplaceinVienna.Couldyoupleaseexplainwhat thiseventis,howonecanparticipate, andifthereisstillanopportunityto submitpapersorabstracts?

TonyBERGEN: Everytwoyearsthe

7CIE’sResearchFora: https://cie.co.at/research-strat egy/research-forum

8CIE’sNewsletterRegistration: https://cie.co.at/abou t-cie-0/newsletter

CIEholdsaplenaryeventwhereallof ourDivisionsmeetalongwithourNationalCommitteesandothergovernance structures.Themostsignificantofthese areourCIEQuadrennialSessions,where inadditiontoholdingascientificconferenceandothermeetingswealsohave a“changingoftheguard”–transitionof CIEPresidentaswellasBoardmembers,DivisionDirectors,etc.,whoall servefour-yearterms.Inthemiddleof eachquadrenniumwethenholdaCIE MidtermMeeting,andthatiswhatwillbe happeninginViennainJuly2025.

AttheCIEMidtermMeeting,thereare face-to-facemeetingsoftheGBand TMB;aGeneralAssemblyattendedby representativesfromourNationalCommittees;athree-dayscientificconference;andthreedaysofDivisionand TechnicalCommitteemeetings.Thenew CIEPresident-Elect,whowillleadthe CIEinthe2027-31quadrennium,will alsobeannounced.

Thewebsiteforthescientificconference9 isalreadyupandrunning,and Iampleasedtosharethatourthree keynotespeakershavealreadybeen announced.Thereisstillplentyoftime tosubmitashortpaper(whatinprevious conferencesweusedtocallanextended abstract):Thecloseofsubmissionswill be10thDecember2024.

AsImentionedearlier,myfirstexperienceintheCIEwasataCIEplenary eventandformeitwasalife-changing experience.Tohavesuchanopportunity tolearn,tobearoundthebestmindsin ourfield,tomeetpeoplefromallaround theworld,wassimplyamazingandI havebeentoeveryonesince!Viennais suchabeautifulcityandI’malsoreally excitedbythesocialprogramsthatare planned.

LEDprofessional: Movingtowardsthe endofourinterview,wewouldliketo askhowyouforeseethefuturedevelopmentoftheCIE’swork.Arethere significantnewtrendsthathavealreadybeenincorporatedintothework andpotentiallynewapproaches?

TonyBERGEN: Ithinkthatthedigital transformationwillcontinuetoimpact ourlivesasithasdoneoverthepast decadeormore.SinceCOVIDwehave becomeusedtoonlinemeetings,and 9ScientificConferenceWebsiteofCIE’sMidterm Meeting2025: https://vienna2025.cie.co.at/

Ifeelthatourworkhasbecomemore efficientasaresult,sinceourTechnical Committeescanmeetmorefrequently toprogresstheworkratherthanjust meetingface-to-faceonceperyearas typicallyhappenedinthepast.Ithink thatwewillalsoseeincreasinguseof collaborativeprogramstocoordinateour technicalwork.

Wenowhaveallofourmaindatasets freelyavailablefromtheCIEwebsitein amachine-readableformat(csvdataset withjsonmetadatafileandchecksum), fromcolormatchingfunctionstospectral distributionsofreferenceilluminants.If anybodyhashadthefunjoboftypinga tablefromabookintoaspreadsheet,as Ihavedoneinthepast,Iinviteyoutogo toourwebsite10 andcheckoutthelistof datasetsthatarenowavailableandcan beeasilydownloaded.

Severalofourrecentpublicationshave alsohadspreadsheetsavailable–both astoolboxesandasexamplecalculations.Ithinkthatthisislikelytobemore commoninfuture.

LEDprofessional: Wouldyouliketo giveafinalstatementtoourreaders regardinglightingtechnologies?

TonyBERGEN: AsImentionedearlier, mymaininvolvementwiththeCIEhas beeninDivision2whichdealswithmeasurementandmeasurementdevices. AlthoughIhaveseenalotofdevelopmentsinthetechnologyusedinmeasurementovermycareer,oneofthe recentinnovationsthatIhavebeenincrediblyimpressedwithispersonallight dosimeters(Figure 1).Theseareminiaturizedmeasurementdevices,usually performing(quasi)spectrallyresolved measurements,whichpeoplecanwear astheygoabouttheirdailyroutine,and whichlogtheirlight“diet”.Ihaveanalyzedsomeofthesedevicesinourlab andIamreallyimpressedwiththeirqualityofmeasurementintermsofaccuracy anddynamicrange.

Wehadaworkshopearlierthisyearto celebrate100yearsoftheV(λ)function thatunderpinsphotometry.TheCIEhas publishedworkonconefundamentals, whichoffersnotonlyamoreaccurate matchtoourphotopicvision,butalso theabilitytoadaptthistoaperson’sage andthefield-of-viewofwhattheyare lookingat.

10CIE’slistofdatasets: https://cie.co.at/data-tables

Theminiaturizedmeasurementdevices Ijustmentionedhavetheabilitytoprovideadaptabilityofmeasurement:tolink photometryandintegrativelightingand conefundamentals,andIthinkthatthis willbeanexcitingdevelopmentoverthe nextdecade.

LEDprofessional: BelatedcongratulationsonreceivingthedeBoerGold PinAward!Itwasapleasureandan honortospeakwithyouaboutthe CIEandlightingtopics.Thankyou verymuchforyourtime,valuableinsights,andcontributionstothelightingsector!

TonyBERGEN: Thankyou!Itwasa greathonortobepresentedwiththe deBoerGoldPinAwardatourQuadrennialSessioninLjubljanalastyear. Itisalsoanincrediblehonortoserveas Vice-PresidentTechnicaloftheCIE.Althoughitmeansalotofverylatenights (forme,livinginMelbourne,meetingsare oftennotsoconvenient)andahighlevel ofresponsibility,ithasso-farbeenvery rewardingandIlookforwardtothechallengesofthefuture.

Thankyouverymuchfortheinterview. ■ Foradditionalinformation,pleasevisit https://cie.co.at.

6-starHospitalityApproachforthe

ShoppingMallNanjinginChina

LichtvisionDesign

LichtvisionDesignhadtheexcitingopportunitytoredefineluxuryretailfor theIFCNanjingShoppingMall.Lead8, astheretailplannerandinteriordesignerforthisdevelopment,adopted aunique6-starhospitalityapproach forthisprestigiouslandmarkinNanjing.LichtvisionDesigndevelopedan elegantandintegratedlightingdesign solutiontoenhancethecontemporary classicversionofavintageartnouveauinteriorstyle.

Thegoalwastoweavelightintothemall’s identity,usingittotellastory,evokeemotions,andguidevisitors.Thedesignprocessbeganbyhighlightingthemall’sarchitecturalelegancewithgentleyetdramaticlighting,transformingcolumns,staircases,andfacadesintocaptivatingfocal points.Thelightingdesignfeaturedceilingrecesseddownlightsanddirectlinearlights forgeneralillumination,whiledecorative coveluminairesprovidedaccentlighting. LEDsolutionswereselectedtoprioritize energyefficiency,balancingbeautywith sustainabilityandaligningwiththemall’s operationalgoals.

Nanjing,IFC–Nanjing,China

Typology: ShoppingMall

LightingDesign: LichtvisionDesign

ScopeofWork: ArtificialLighting

Completion: 2024

Location: Nanjing,CHina

Size(i.e.GFA): 93,000m²

Client/Owner: SunHungKaiProperties

Tenant/User: SunHungKaiProperties

ProjectTeamLichtvisionDesign: SunniaCheng,JaneTsai,JeffHung,Jenny Chan

DesignArchitect: Lead8

LocalArchitect: Lead8

AdditionalPlanningPartners: Dop Design

Contractor: GuangzhouPearlRiverDecorationEngineeringCo.,LTD

Photographer: (c)LichtvisionDesign

LightingSupplier: WAC,Ricardo

LightingControls: Dalitek

ProjectContact&Links hongkong@lichtvision.com

Theprojectpresentedsignificantchallenges,particularlywiththehigh-glossand darkmaterialsintegraltothemall’sbrand. Combiningdiffuselightingwiththesematerialsrequiredspecialcaretoavoidglare andreflections.Determiningoptimalilluminationlevelswascritical,involvingnumeroustests,verifications,andmock-ups. Thisprocessestablishedastandardmodel forthebrand’silluminationlevels.Thelightingwasdesignedtoevolvethroughoutthe day,enhancingtheshoppingexperience frombrightandenergizingmorningstorelaxedafternoonsandmagicalevenings. Seamlesslyintegratedfixturesensured acohesivemoderndecor.Throughthis meticulousapproach,LichtvisionDesign turnedlightintoastoryteller,makingthe IFCNanjingShoppingMallamemorable destination.

ThebasisofthedesignfortheNanjingIFC projectfocusesonacomprehensiveapproachtolightingthatbalancesaesthetic, functional,andenergyefficiencyconsiderations.Duringthedevelopmentofthe schematicdesign,keyareaswithinthe projectwereevaluatedfortheirspecific lightingneeds,appropriatelampsources, andtheachievementoftargetaverage illuminancelevels.Eachspacewasassessedtoensurecompliancewithmaximumallowablepowerdensities,aligning withenergyefficiencygoals.Thedesign alsoaccountedfortheuniformityoflighting (Uo),colorrendering(Rarating),andvisual comfort(UGR).

Thisstructuredapproachensuredthatthe designmetboththefunctionalrequirementsandtheaestheticaspirationsofthe projectwhileadheringtocostestimates andsustainabilitybenchmarks.

https://www.lichtvision.com/en

NanjinghasaspecialplaceinChinese history.Thecitywasthecapitalofseveral greatkingdomsandgovernments.That’s whyNanjingisessentialinunderstanding China’shistory.Thecitydelicatelybalances theoldandnew,thetraditionalandthe modern.Itsimpressive14thcenturycity wallcanstillbeseentoday,togetherwith severalmonumentalcitygates.Nanjing boastsmanyimpressivesitesfromdifferent historicalperiods,includingthefamous NanjingDecade.Whenitcomestomodern architecture,Nanjingdoesn’tdisappoint either.

Nanjing’sofficialnameliterallymeans SouthernCapital.ThewordNanmeans thesouth,andthewordJingmeanscapital.TheMingDynastygaveNanjingits namein1403todistinguishitfromits northerncapital,Beijing.Infact,from1403 to1644,theMingDynastyruledChina frombothcapitals.However,Nanjinghad othernamesthroughoutitshistory.Jiangning,forinstance,ismadeoftwoabbreviations.JiangisshortforJiangsu,the encompassingprovince,andNingshortfor Nanjing.WhenNanjingwasthecapitalof theRepublicofChina,peoplecalleditJing, meaningcapital.

NanjingisChina’seight-largestcity,ahead ofWuhanandXi’an.Accordingtothelatestinformation,theurbanpopulationof Nanjingis8.5millionpeople.

TransformingGeneralLighting–TheCost-savingPotentialofZonal Lighting

MatthiasBoeserandDr.ThomasSchielke,ERCO

UnlockingthePotential ofZonalLighting: 5StepstoTransform GeneralLighting

1. AnalyseSpaceandLightingNeeds Assessthelightingrequirementsfor differentareasconsideringtaskperformanceandvisualcomfort.

2. SelectanAppropriateLighting Strategy

Evaluatethebenefitsofazonalscheme andverticallightingincomparisontoa gridlayout.

3. PrioritizeEnergyEfficiencyand Quality

Don’tlethighlm/Wvaluestakethe placeofspaceefficiencymetricsand long-termqualitybenefits.

4. IntegrateAdvancedControls Implementdaylightdimmingandoccupancysensorstomaximizeenergy savings.

5. PlanforLong-TermValue

Optforsolutionsthatbalanceupfront costswithlong-termbenefitsinenergy savingsandreducedmaintenance.

Intoday’spushforresourceefficiency andenergysavings,theeffectivenessoflightingismorecriticalthan ever.Investingwiselyinlightinggoes beyondmereillumination;itencompassescreatingahuman-centered environmentthatimproveswell-being andensureslong-termeconomicefficiency.Thispaperspecificallylooksat generallightingstrategiesforoffices. Anapplicationwheretraditionaluniformlightingapproachesoftenleadto inefficienciesinenergyuseandworkplacesatisfaction.

Today,LEDdownlightsallowdifferentconceptssuchasthatofzonallighting,astrategythattailorslightdistributiontospecific areaswithinanoffice,optimizingbothenergyconsumptionandvisualcomfort.In contrasttouniformlightinggrids,zonal lightingstrategicallyreducesthenumber ofluminairesneeded,resultinginsignificantenergysavingsandlowerinvestmentcosts.Thesesavingsallowforinvestmentinhigher-quality,durabledownlights, whichofferlongevityandminimalmaintenance,ultimatelyreducingtotaloperating costs.

Thiswin-wininvestmentnotonlyenhances thequalityoflightincriticalworkareasbut alsopromotesahealthier,moreproductive workplace.

Differentstakeholdersinterpreteconomic efficiencyinvariedways.Buildingservices engineersseekstandard-compliantsolutions,architectsprioritizevisualdesign,and clientsfocusonlowoperatingcostsand long-termvisualappeal.Theywillallgain insightsintosmartlightingplanning,the roleofadvancedcontrolsystems,andthe importanceofconsideringecologicaland socialfactorsinyourinvestmentdecisions. Comparingfourgenerallightingmethods, wewillguideyouthroughenergyefficiency metrics,highlightingtheshortcomingsof conventionalpracticesandshowcasingthe advantagesofeffectivezonallighting.

Gridlightingapproach(top).Zonelighting approach(bottom). Zoningthefloorplaninthis casestudyrevealsthatofficedesks,requiring thehighestluxlevels,constituteonly14%ofthe officespace.Withoutzoning,theofficeareawith 500lxwouldmakeup58%ofthefloorplan.This highlightsasignificant,oftenunderestimated potentialforcostsavingsingenerallighting. BalancingEfficiencyMetrics

andLightingQualityin GeneralLighting

Thepushforenergyefficiencyhasledto thewidespreadadoptionofmetricslike lumensperwatt(lm/W)orwattpersquare metertoevaluatelightingsystems.While thesemetricsprovidevaluableinformationaboutenergyconsumption,theyoftenfailtoaccountfortheoverallqualityof thelightingenvironment.Thiscreatesa

Luminaire-basedvs.application-basedefficiencymetrics: Althoughgreenbuildingstandardsand publicfundingoftenrequirehighluminousefficacy,lm/Wisaluminaire-basedmetricwhichsimply measuresalightsource’sefficiencyinconvertingpowertolight.Incontrast,application-basedmetricslike W/m2evaluatetheefficiencyoftheentiregenerallightingsystemwithinaspecificspace,considering distributionandusagepatterns.Ahighlm/Wisthereforenoguaranteeforaneffectiveand resource-efficientlightingscheme.

Comparinglightingefficiency–keymetricsexplained: Commonlyusedefficiencymetricsfocuson energyconsumptionanddonotaddresslightingqualityaspectslikevisualcomfortanddistribution. W/sqm,forinstance,comparesenergyefficiencyacrossdifferentschemesormanufacturersbuthas limitations.Itdoesn’taccountforvariedlightingusageorthebenefitsoflightingcontrols,focusingonlyon totalconnectedload.Incontrast,kilowatt-hourperyear(kWh/a)reflectsannualenergyconsumptionand theadvantagesoflightingcontrols.Therefore,kWh/aoffersamorecomprehensiveevaluationespecially whenmakinguseofdaylightandpresencesensors.

dilemma:designersmustbalancethepressuretomeetefficiencystandardswhilealso ensuringthatlightingqualityisnotcompromised.

Forinstance,highlm/Wvaluesindicatea luminaire’sefficiencyinconvertingelectrical powertovisiblelight.However,thismetric

doesnotconsiderhowwellthelightisdistributedacrossaworkspaceoritsimpact onvisualcomfortandproductivity.Proper lightdistribution,glarecontrolandcolor renderingareessentialaspectsoflighting qualitythatsignificantlyaffectuserexperienceandoverallsatisfaction.

Lightingqualityremainslargelytheresponsibilityofthedesigner.Effectivelighting designmustconsidervariousfactors,includingthespecificneedsofthespace, thetasksperformedandthewell-beingof theoccupants.Forexample,anofficeenvironmentrequiresdifferentlightingsolutions thanafoyeroracirculationareainanairport.Factorssuchasuniformity,contrast ratiosandtheabilitytocontrollightlevels playcrucialrolesincreatingacomfortable andefficientworkspace.

Moreover,thelong-termbenefitsofhighqualitylightingsystemsoftenoutweighthe initialcostsavingsoflessexpensiveoptionswhichmayhavehigherlm/Wratings onpaper.Factorsthatcontributetothe totalcostofownership(TCO)includenot justtheinvestmentandinstallationbutalso energycosts,maintenanceandreplacement.Inaddition,thereareindirectcosts associatedwithemployeeperformance andhealth.Superiorlightingcanenhance employeeproductivity,reduceeyestrain andevenimprovemoodandwell-being, leadingtolowerabsenteeismandhigher overallperformance.

Althoughtosomeextentinsufficient,we mustacknowledgetheimportanceoftoday’sefficiencymetrics.Theyarewidely usedandprovideastandardizedwayto comparedifferentlightingsystems.Understandingandworkingwiththesemetrics isessential,evenaswestrivetoadvocate foramoreholisticapproachthatincludes lightingqualityasacriticalcomponent ofenergyefficiency.Recentlypublished methodslike“lightingapplicationefficacy” mightbecapableoffillingthisgap.

ChoosingtheRightGeneral LightingStrategy:A ComparativeAnalysis

BuildingandReferenceFloorDescription

Inthiscasestudy,weanalysethegeneral lightingstrategiesforatypicalofficebuildingdesignedbyaprojectdeveloper.The buildingfeaturesanH-structurethatmaximizesdaylightaccesswithgroupoffices andaconventionallayoutwithacentral corridor.Thereferencefloorhasaheightof 2.7metersandasuspendedceiling.One floorisdesignedtoaccommodate147 desks,takingup25%ofthetotaloffice areaof767squaremeters.Eachlighting strategywascalculatedusingrecessed downlightswith4000KCRI82LEDmodulesandDALIcontrolfordaylightdimming.

ThebuildingfeaturesanH-structurethatmaximizesdaylightaccesswithgroupofficesanda conventionallayoutwithacentralcorridor.

GridLayout–SimplicitywithHigher EnergyCosts

Thegridlayoutemploysauniformarrangementofluminairesthroughouttheoffice space.Thisapproachsimplifiesplanning andimplementation,offeringauniversal lightdistributionthatisindependentofspecificfurniturelayouts.However,itresultsin highenergyconsumptionduetouniform highilluminanceacrosstheentirearea, makingitinefficientforspaceswithvaried lightingneedsandpotentiallyleadingto over-illumination.

Schematiclightinglayout.

Visualappearance.

• Piecesinstalled:381pcs

• Energyconsumption:3.2W/m2

• LENI(withcontrols):64kWh/m2·a

• ERCOsolution:59€/m2

ZonalLighting–EfficiencyThrough Precision

Zonallightingtailorsilluminationtospecificareasbasedontheirrequirements. Thisstrategyprovidessignificantenergy savingsbyusingdownlightswithdedicatedlightdistributions.Lightingonlythe necessaryareasreducesthenumberof luminairesneededandlowersbothenergy consumptionandtheinitialinvestment.On thedownside,itrequiresdetailedplanning toaccommodatefurnitureandlayout,and thereisapotentialforunevenlightingifnot carefullydesigned.

Schematiclightinglayout.

Visualappearance.

• Piecesinstalled:245pcs

• Energyconsumption:2.4W/m2

• LENI(withcontrols):29.4kWh/m2·a

• ERCOsolution:47.40€/m2

ZonalLightingwithWallwashing–EfficientVisualComfort

Thisstrategyenhancesthezonallightingapproachbyaddingwallwashingto improvevisualcomfortandaestheticsto theirhighestlevels.Itcombinesenergy efficiencywithimprovedvisualcomfort andmeetsthenewEN12464standardfor balancedlightdistribution.Ahigherinitial investmentduetotheadditionalluminaires neededforverticalilluminationisoffsetby highvisualandamenityquality.

• Piecesinstalled:314pcs

• Energyconsumption:3.3W/m2

• LENI(withcontrols):39.3kWh/m2·a

• ERCOsolution:66.62€/m2

Schematiclightinglayout.

Visualappearance.

PendantDownlightswithIndirect Lighting–CombiningDirectand IndirectLight

Usingpendantdownlightswithanindirect lightingcomponentprovideszonaland efficientlighting.Thisstrategyisenergyefficientbyfocusinglightwhereitisneeded andenhancingvisualcomfortwithindirectlight,whichreducesglare.However,it requiresmeticulousplanningtoensureadequateindirectlighting,anditmayinvolve highercomplexityandpotentiallyhigher initialcosts.

Schematiclightinglayout.

Visualappearance.

• Piecesinstalled:197pcs

• Energyconsumption:3.4W/m2

• LENI(withcontrols):58.4kWh/m2·a

• ERCOsolution:70.49€/m2

Summary

Thiscasestudycomparesfourdistinct generallightingstrategiesforatypical officesetting,eachofferinguniqueadvantagesandchallenges.Theanalysis underscoresthesubstantialimpactthat thoughtfullightingdesigncanhaveon bothenergyefficiencyandvisualcomfort.Thegridlayout,whilestraightforward andeasytoimplement,resultsinhighenergyconsumptionandinefficienciesdue toitsuniformilluminationacrossallareas, regardlessofspecificlightingneeds.

Incontrast,zonallighting,whichcustomizesilluminationbasedontherequirementsofdifferentareas,significantlyreducesenergyusageandthenumberof luminairesneeded.Thisapproachnot onlyreducestheinitialinvestmentcosts but,togetherwithdurable,high-quality downlights,leadstolowermaintenance andoperatingcostsovertime.Theadded complexityinplanningcanbemitigated withcarefuldesignandimplementation. Wallwashingtakesthisastepfurtherbyincorporatingverticalilluminationtoenhance visualcomfortandaesthetics.

ThisstrategymeetsthelatestEN12464 standardforbalancedlightdistribution, providingawell-roundedlightingsolution thatsupportseconomic,functionaland aestheticneeds.

Thefindingsfromthiscasestudyemphasizestheimportanceofintegrating energyefficiencymetricswithaholistic viewoflightingquality.Understandingthe strengthsandlimitationsofeachlighting strategyallowsforbetterdecision-making andoptimizedlightingsolutions.These insightshighlightthevalueofinvestingin high-quality,durableluminaireswithdedicatedlightdistributions.

Byleveragingadvancedlightingstrategies,everyonecanachievesuperiorenergy efficiency,enhancedvisualcomfort,and long-termeconomicbenefits,makinga compellingcasefortheadoptionofinnovativelightingsolutionsinfutureprojects. ■

Downlightingstrategiescompared.

AboutERCO

ERCOisaninternationalspecialistforhighqualityanddigitalarchitecturallighting. Thefamily-ownedcompany,foundedin 1934,operatesgloballyin55countries withindependentsalesorganizationsand partners.

ERCOunderstandslightasthefourthdimensionofarchitecture–andthusas anintegralpartofsustainablebuilding. Lightisthecontributiontomakingsociety andarchitecturebetterand,atthesame time,preservingourenvironment.ERCO Greenology®–thecorporatestrategyfor sustainablelighting–combinesecological responsibilitywithtechnologicalexpertise.

AtthelightfactoryinLüdenscheid,Germany,ERCOdevelops,designsandmanufacturesluminaireswithafocusonphotometricoptics,electronicsandsustainable design.Thelightingtoolsaredevelopedin closecollaborationwitharchitects,lighting designersandelectricaldesigners.They areusedprimarilyinthefollowingapplications:WorkandCulture,Community andPublic/Outdoor,Contemplation,Living,ShopandHospitality.ERCOlighting expertssupportdesignersworldwidein transformingtheirprojectsintorealitywith highlyprecise,efficientandsustainable lightingsolutions.

www.erco.com

MatthiasBoeser: MatthiasBoeser,a lightingdesigntrainerandapplicationspecialistatERCO,startedwithprofessional stagelightingandhasbeenworkinginarchitecturallightingdesignformorethan20 years.Hehasbeenalecturerforlighting designandlightingtechnologyinvarious degreeprogramesformorethan15years.

Dr.ThomasSchielke: ThomasSchielke, atraineratERCOforarchitecturallighting,hasbeenworkingatERCOformore than20years.Hisextensivecontributions includeanonlineguide,workshops,and internationalarticlesonlighting.ThecoauthorshipoftheERCObook“LightPerspectives”reflectshisexpertise.Hehas presentedlecturesatvariousinternational universities.

MarkS.Rea1,2,RohanNagare1,JohnD.Bullough1,andMariana G.Figueiro1,LightandHealthResearchCenter

Circadiandisruption,abreakdown intheregularityofactivitypatterns acrossthe24-hday,canleadtoavarietyofmaladies.Someindividuals andorganizationsobjecttothetwiceyearly,seasonalchangesinlocaltime becauseitcontributestocircadiandisruption.Thenumberofdaysrequired tore-entrainthecircadiansystemto thenewlocaltimefollowingtransitions toorfromdaylightsavingtimeisnot completelyunderstood,butseveral simplerulesofthumb(i.e.,heuristics) havebeenofferedtominimizethedays tore-entrainmentand,thus,circadiandisruption(e.g.,goforamorning walk).Recently,theauthorsdeveloped acomputationalmodelforpredictingcircadianphasefromcalibrated light-darkexposurepatterns,based largelyonthepioneeringworkofKronauerandcolleagues.Thismodelwas usedheretopredictthedaystoreentrainmentofthecircadiansystems of“larks”and“owls”toanewlocal timeiftheywereexposedtooneof threespecificlightinterventions.Simulationsshowedthatthetimingofa lightinterventionmustaccountfor chronotypes(e.g.,timingofminimum corebodytemperature)anddirection ofshift(i.e.,phaseadvanceordelay) toachievere-entrainmenttothetime changemorequickly.Simpleheuristicsarenotnecessarilyadequatefor minimizingthedaystore-entrainment.

Introduction

1 LightandHealthResearchCenter,DepartmentofPopulationHealthScienceand Policy,IcahnSchoolofMedicineatMount Sinai,NewYork,NY,UnitedStates

2 MarkS.Rea, mark.rea@mountsinai.org

Modelsaredevelopedtohelpusunderstandnaturalphenomena.Whethersimple heuristicsorcomplexalgorithms,thevalue ofanymodeldependsuponitsabilityto accuratelypredictnaturalphenomena, bothintermsofdirectionandmagnitude. Thepresentstudyemploysarecentlypublishedcomputationalmodel,thecircadianstimulus(CS)-oscillatormodel(Rea etal.,2022),whichisaimedatpredicting light-inducedphasechanges,toacceleratere-entrainmentfollowingtheshift fromstandardtimetodaylightsavingtime, andviceversa.Someofthosepredictions arecountertocommonheuristics(Tumin, 2023;Suni,2024)forreducingcircadian disruption.Sincetheseminalpublication ofCircadianClocks(Aschoff,1965),much hasbeenlearnedaboutthehumanmasterclockinourbrainandhowitstimingis affectedbylightexposureontheretina. Ideally,themasterclockwillsynchronize orentraintothelocal,dailycycleoflight anddark.Throughentrainment,themasterclockorchestratestheidealtimingfor executingourphysiologicalandbehavioral functionsovertheentire24-hdailycycle. Indeed,itistheabilityofthemasterclock toanticipatewhatneedstohappen,and when,thatmakesthecircadiansystem soremarkable.Withoutaconsistent,synchronizing24-hcycleoflightanddark, however,themasterclocklosesitsability toaccuratelyanticipateandthencontrol thebesttimingofphysiologyandbehavior. Ashasbeenshownininnumerablestudies,healthandreproductivesuccess(Miller andTakahashi,2014;Swamyetal.,2018) arecompromisedbydisruptionofaregular circadiancycleresultingfromdisruptionof aregular24-hcycleoflightanddarkexposureontheretina.

Themountainofaccumulatedknowledge aboutthemasterclockinresponseto lightcanideallybeboileddownintosimpleheuristicsforpromotingcircadianentrainment(e.g.,ULStandards&Engagement(2019))andthus,betterhealth.By consistentlyexposingourretinatobright daysanddarknights,themasterclock canconsistentlyinfluencewhatbiologicallyneedstohappenatwhattime(s)and therebycanorchestratetheentirecircadiansystemforbetterchancesofsurvival andreproduction.Butweclearlydonot alwaysbehaveinaccordancewiththat simplerubric.Rather,asahighlyintelligent andhighlysocialspecies,wefindmany waystobreakthesynchronybetweenthe natural24-hlight-darkexposurepattern andthelight-darkexposureprofilesthat weactuallyexperience,therebynegatively impactingthetimingofthemasterclock. Forexample,modernhumanscommonly travelrapidlyacrosstimezones,placing thetimingofthemasterclockatoddswith thenewlocaltimesofsunriseandsunset (Meir,2002).Wealsoworkandplayinto thenight,limitingourexposuretobright lightwhilewesleepduringthedayandextendingexposuretodimlightwellintothe night(Qinetal.,2003).Evenwithoutrapid, trans-meridiantravelorshiftwork,nearly allofuslivingwithinthebuiltenvironment (Cox-GanserandHenneberger,2021)experienceinsufficientlightexposuresduring thedayandprolongedlightexposuresafter sunset(Reiteretal.,2007;Bonmati-Carrion etal.,2014;Smolenskyetal.,2015).

Manypeoplearoundtheglobeexperiencethesuddenchangeinlocalclocktime twiceayear,forcingustore-entrainourbiologicalclocktothenewlocaltime.Therefore,ourcomplicatedmodernlifestyleslimit thepredictivepowerofanysimpleheuristic.Thatbeingthecase,weneedtode-

velopmore-complexpredictivemodelsthat considerthecomplicatedsociologicaland technologicalenvironmentinwhichwelive. Todoso,weneedtointegratethreeconceptualdomainsintoamorecompleteand therebymoreaccuratepredictivemodelof circadianentrainment.

RetinalResponsetoLight

First,wemustdefinelightasitaffectsthe masterclock.Lightisabiophysicalconstructthatreflectsthespectralandabsolutesensitivitiesofthehumanretinato opticalradiation.Thephotopicluminous efficiencyfunction[V(λ)],orthe“eyespectralsensitivitycurve,”wasdevelopedbythe InternationalCommissiononIllumination (CIE)inthe1920s(CommissionInternationaledel’Éclairage,1926)tosupport internationalcommercefortheemerging electriclightingindustrysuchthatalumen (visuallyeffectiveradiantflux)wasthesame inonecountryasitwasinanother.V(λ) wascreatedfromempiricalpsychophysical experimentswithoutthebenefitofaclear understandingofhowthehumanretina convertsopticalradiationintoneuralsignalstothebrain.TodayweknowthatV(λ) representsthespectralsensitivityoftwo conephotoreceptors(L-coneandM-cone) intheretinaastheyfeedonemulti-neuron channelconnectingtheretinatotheconsciousbrain.Wealsonowknowthatthe neuralchannelcharacterizedbytheV(λ) spectralsensitivityfunctiondoesnotfunctionatlowlightlevels,likestarlight.The luminousefficiencyoftheso-calledscotopicchannel[V’(λ)]wasestablishedinthe bytheCIEinthe1950s(JansenandHalbertsma,1951)andischaracterizedby therodphotoreceptoractionspectrum.A scotopicfunctionwasneededbecausethe spectralandabsolutesensitivitiesofrods areverydifferentthanthoseforthetwocone,photopicchannel[V(λ)].Indeed,we nowdescribethehumaneyeashavinga “duplexretina”(Barlow,1972),onechannel fordaytime,photopiclightlevels,andone channelfornighttime,scotopiclightlevels. Astheneurosciencehasprogressedsince the1920sand1950s,wenowknowthat therearefivephotoreceptorsintheretina and,evenmoreimportantly,thattheyall participateinmanyneuralchannelsthat leavetheeyetoreachdifferentpartsofthe brain.Lightforeachofthesechannelswill bedifferentbecausethephotoreceptors andneuronsthatconvertopticalradiation intoneuralsignalsleavingtheeyediffer fromlightthatstimulatesthephotopicor scotopicchannels(Rea,2012).

Oneofthemulti-neuronchannelsleavingtheretina,theretinohypothalamictract

(RHT)oftheopticnerveformedbythe axonsoftheintrinsicallyphotosensitive retinalganglioncells(ipRGCs),reaches thesuprachiasmaticnuclei(SCN),the masterbiologicalclockinthebrain.This light-sensitivechanneldrivesthetimingof thebiologicalclock,where,hopefully,it sendsneuralsignalstosupportarobust synchronybetweentheexogenouslightdarkcycleandtheendogenousdiurnalnocturnalcyclesofphysiologyandbehavior.Notsurprisinglyperhaps,thecombinationsofphotoreceptorsandneurons thatformthisneuralchannelarecomplex. Aquantitativemodelofboththespectral sensitivityandtheoperatingcharacteristicsoftheRHTneuralchannelhasbeen developed(Reaetal.,2021a)that,importantly,isconsistentwithhumanretinal neuralanatomyandphysiology(Reaetal., 2021b).

Briefly,thespectralsensitivityoftheRHT neuralchannel(Figure 1A)ischaracterized bywhatistermedcircadian-effectivelight (CLA).Allfivephotoreceptorsintheretina (L-cone,M-cone,S-cone,rod,andipRGC) contributeto CLA andtheirrelativeparticipationinspectralsensitivitychangeswith theamountofopticalradiationincidenton theretina.Theoperatingcharacteristics oftheRHTchannelaremodeledinterms ofcircadianstimulus(CS),whichquantifiesthemagnitudeoftheneuralsignal generatedbytheretinafromthresholdto saturation(Figure 1B),typicallyfollowinga sigmoid-likefunction(DeLeanetal.,1978; Evansetal.,1993).Darkforthisneural channelcanbedefinedas CLA levels belowCSthreshold,andbrightas CLA levelsaboveCSsaturation.FortheRHT neuralchannel, CLA fromfullmoonlight isbelowCSthresholdbutwellaboverod threshold,and CLA fromdaylight,even onacloudyday,isaboveCSsaturation butwellbelowconesaturation. CLA lev-

elswithintheindoorbuiltenvironmentare almostalwaysbetweenCSthresholdand CSsaturationasillustratedin Figure 1B.

CalibratedAmbulatoryLight Data

Second,weneedtobeabletocapture representativeprofilesofcalibratedlight anddarkexposurestothehumanretina astheymightaffectthetimingofthemasterclock.Ambulatorylightmeasurement devicesmustbeusedsothatthetiming, duration,andamountofthecircadianeffectivelightexposuresarerecordedover thecourseofthe24-hdays.Theselight measurementdevicesmustbecalibrated intermsoftheRHTchannelspectraland absolutesensitivities, CLA andCS,respectively.Ideallythesedevicesshould measureopticalradiationneartheperson’s eyes,butthisisoftennotpracticaloracceptabletotheperson,compromisingthe spatialaccuracyofthesemeasurement devicestovariousdegrees(Figueiroetal., 2013).Thefirstsuchcalibratedcircadianeffectivelightmeasurementdevice,the Daysimeter,wasdevelopedin2005(Biermanetal.,2005).Thesensorwasworn neartheeyesandincludedthreeoptical sensors(RGB).Throughpost-processing, thespectralsensitivityandtheoperating characteristicsoftheRHTneuralchannel wereusedtoestimatethemagnitudesof thecircadian-effectivelightexposuresevery 3minthroughouttherecordingperiod,typicallyoversevenconsecutivedays.

SeveraliterationsoftheDaysimeterhave sincebeendeveloped(Biermanetal., 2005;Milleretal.,2010;Reaetal.,2010; Figueiroetal.,2013).Theaccuracyofthe calibrationhasimprovedasabetterunderstandingofthespectralsensitivity(i.e., CLA 2.0)(Reaetal.,2021a)andoperat-

Figure1: SpectralsensitivityoftheRHTchanneltomonochromaticsourcesandtopolychromatic“warm” (b(blue)–y(yellow)≤0)and“cool”(b–y>0)lights(A).OperatingcharacteristicoftheRHTchannelfrom thresholdtosaturation(B);thevaluegradientillustratesCLAlevelsthatwouldcommonlybefoundin differentlocationsandtimesofday.AlsoshowninpanelBaretheaverageCSlevelsmeasuredduringthe dayandduringthenight(beforebedtime)forthetwoexemplarsubjectsinthepresentstudy(see “Exemplarsubjectprofileselections”).

ingcharacteristics(i.e.,CS)ofthechannel hasincreased.However,againunderscoringthecomplexityofhumanbehavior, thespatialaccuracyoftheDaysimeter hasbeencompromisedtosomedegree because,asnotedpreviously,subjects havebeenreluctanttowearthedevice neartheeyesasitwasoriginallydesigned (Figure 2A).SubjectsweremorecompliantwhentheDaysimeterwasworn asapendant(Figure 2B)without,unlike wrist-worndevices,compromisingaccuracycomparedtomeasurementsatthe eyes(Figueiroetal.,2013).Notwithstanding,continuouscalibratedambulatorylight measurementsacrossseveraldaysareessentialforcharacterizingthe24-hlight-dark exposurepatternthatsynchronizes,ordisrupts,thebiologicalclockwithrespectto aperson’slocalpositiononEarth.Without thatinformation,itisimpossibletocharacterizecircadianentrainmentorhowalight interventionmightaffectentrainment.We haveusedtheDaysimeterin Figure 2B successfullyinseveralfieldstudies(Figueiro etal.,2014;Reaetal.,2016).

ResponseoftheBiological ClocktoRetinalInput

Third,oncetheRHTneuralchannelsignaltotheSCNhasbeenquantified,itis thennecessarytomodelhowthebiological clockprocessesthatsignalfordownstream communicationofcircadianphasetothe manyvarioussystemsthatgovernour physiologyandbehavior.Kronauer(1990) andcolleagues(Kronaueretal.,1999)developedavanderPoloscillatormodelof theSCNwherebyitsphasechangedin responsetophoticinputfromtheretina, measuredintermsofphotopic(twocone) illuminance.Severalinvestigationshave utilizedthismodel,orvariationsonit,to predictlight-inducedphasechangesquantifiedintermsofthepredictedchanges inclocktimefortheminimumcorebody temperature(CBTmin),acommonmarker ofcircadianphase(Refinetti,2020).Many ofthesestudieshavebeeninalaboratorysetting(StHilaireetal.,2007;Mott etal.,2011)whileothershaveusedpersonallightmeasurementdevicesinthefield (Woeldersetal.,2017;Huangetal.,2021). Allofthesestudiesshowapredictiveaccuracyofphotopic(twocone)light-induced circadianphasechangesnobetterthan approximately1h.

TherecentlydevelopedCS-oscillator model(Reaetal.,2022)retainsthebasicstructureoftheKronaueretal.(1999) model,butthephoticinputisdefinedin termsofCS(Reaetal.,2021a;b).Four independentstudiesmeasuringcircadian

Figure2: ExamplesoftheDaysimeterwornneartheeyes(A)andwornasapendant(B).Imageswith permissionoftheLightingResearchCenter.

phasechanges(Sharkeyetal.,2011;Applemanetal.,2013;Figueiroetal.,2014; Reaetal.,2016),beforeandafteralight intervention,wereusedtocomparethe predictiveaccuraciesoftheKronaueretal. (1999)andCS-oscillatormodels.Inthese fourstudieslightmeasurementdevices (Daysimeter)calibratedintermsofphotopicilluminance(lux)or CLA wereused tocontinuouslymeasurepersonallight exposuresover24hforoneweek.The predictedphasechangesindimlightmelatoninonset,anothermeasureofcircadian phase,rangedfrommeanabsoluteerror (MAE)between0.91hand1.43husing theKronaueretal.(1999)model,withan averageMAEof1.07h(1h,4min).With theCS-oscillatormodeltherangeofMAE valueswasnarrowedtobetween0.59h and0.63hwithanaverageMAEof0.61 h(37min).Toreachthislevelofaccuracy fromtheCS-oscillatormodel,theinitial circadianphaseofanindividualmustbe accuratelyestimatedtoproperlyassess theimpactofalightinterventiononaltering circadianphase.Itisalsoworthnotingthat theentire24-hexposurepatternisneeded forthislevelofaccuracy,underminingthe simpleheuristicoftenrepeatedthatonly lightexposuresduringthemorningandthe eveningneedtobeconsideredtopredict phasechanges.

GoalofthePresentStudy

Thepresentstudyutilizesinformationin allthreeaforementioneddomainstopredicthowcircadianphaseisaffectedby personallightprofilesexperiencedbytwo workingadults,atypical“morning”(lark) typeandatypical“evening”(owl)type (Lacketal.,2009),beforeandafterthe twice-yearlyseasonalchangesinlocaltime attwogeographicallydistantUScities (BostonandDetroit),butwithinthesame

(Eastern)timezone.Webeginwithexemplar,seven-day,24-h,light-dark(and activity-rest)patternsobtainedfromcalibratedDaysimetersthatwerewornas pendants(i.e.,asin Figure 2B)bythetwo individuals.TheDaysimeterrecordsraw photiclightlevelsfromthreechannels,R, G,andB,andmovementfromthreeorthogonalaccelerometerchannels,x,yand z.Throughpost-processing,calibrated lightlevelscanbequantifiedintermsof photopicilluminanceinlux,orcircadianeffectivelight,at CLA 1.0(Reaetal., 2010)or CLA 2.0(Reaetal.,2021a;b) levels.The CLA 2.0levelsrepresenta refinedversionofthe1.0versionofthe modelusedtocharacterizelightforthecircadiansystem,basedonrecentnocturnal melatoninsuppressiondatacollectedto testpredictionsfromthe1.0version(Nagareetal.,2019b;Nagareetal.,2019c;d). Fromtheprocessed CLA levels,CSlevels canthenbedetermined(Reaetal.,2021a; b).Fromtheprocessedaccelerometer data,anactivityindex(AI)isdetermined (Milleretal.,2010).AIistherootmean square(RMS)deviationinaccelerationin thethree(x,yandz)accelerometerchannelsforeachlogginginterval.

FromtheCS-calibrated,seven-daylightdarkpattern,theCS-oscillatormodelwas engagedtopredict CBTmin withrespect tolocaltimebefore-and-afterthetransitiontimestostandardtime(ST)duringthe autumn(November)andtodaylightsavingtime(DST)duringthespring(March). Fromthetwo,larkandowl,before-andafterdeterminationsof CBTmin,thedays tore-entrainment(DTR)werethendetermined.DTRisdefinedasthenumberof daysittakesfortheinternalbiologicalclock ofanindividualtotemporallyre-alignitself tolocalclocktimefollowingtheautumnor thespringtransition.Theexemplarylightdarkpatternswerethenvirtuallymodified

inseveralwaystoillustratehowtheCSoscillatormodelcouldbeusedtopredict DTRfollowingthosevirtuallightinterventions.Agoalofthepresentstudywasto determinehowvarious,practicallightinterventionscouldbeusedbylarksand owlstominimizeDTRfollowingthetwo seasonalchangesinlocalclocktime.Recognizingtheinfinitevariationsinbehavior patterns,lightexposurepatterns,individual chronotypes,andgeographicallocation, ourgeneralgoalwastodevelopamorerefinedandaccuratesetofheuristicssothat individualscouldmorerapidlyadjusttothe transitiontoandfromDST.

Methods

ExemplarSubjectProfile Selections

Figures3Aand3bshow7-dayaverage dailylevelsofCSandAI(arbitraryunits)for twoemployedsubjects(denoted“A”and “B”)whoparticipatedinoneofourLight andHealthInstituteonlineeducationalprogramsinSeptember2022.Subjectswere permanentdaytimeworkersandworethe Daysimeterasapendantforaweekat theirhome/worklocationpriortobeginningtheprogram.Avarietyoftabulated metricsderivedfromtheDaysimeterdata areshownin Table 1.Ofparticularnote, CBTmin (see“DaystoRe-entrainment” fordetermining CBTmin),wascalculatedfromtheCS-oscillatormodel(Rea etal.,2022).Baseduponthatdetermination,subjectAwasclassifiedasa“lark” (Figure 3A)andsubjectBwasclassified asan“owl”(Figure 3B)(GaleandMartyn, 1998;Roennebergetal.,2003).Theterms larkandowlareusedheretocharacterizetheirrelative CBTmin times,bothof whichlienearthecenteroftherangefor “morningtypes”andfor“eveningtypes,” respectively(Lacketal.,2009).Inthecontextofexemplarsubjectselectionforthe presentstudy,however,wewantedtonot onlyselectsubjectswhoweredifferentin termsoftheirpredicted CBTmin,butwe alsowantedtoselectoneswhowere“typical”ofindividualsworkingandresiding indoorsmostoftheday,giventhatmost Americansspend90%oftheirtimeindoors (U.S.EnvironmentalProtectionAgency, 1989).Itisnoteworthythattheirphasor magnitudes,indicatingthestrengthofthe synchronizationbetweenthe24-hlightdarkand24-hactivity-restrhythms(Reaet al.,2008),wereverysimilar,indicatingthat bothsubjectswereequallyentrainedto theirpersonallight-darkexposurepatterns andtheiractivity-sleepschedules.Consistentwiththesimilarphasormagnitudes,

Figure3: Temporallight-darkexposure(CS,shaded)andactivity(AI,solidline)profiles,eachaveragedover sevendays,forsubjectA,thelark(A),andsubjectB,theowl(B).Thestarrepresentsthetimeof CBTmin baseduponthelight-darkexposureprofile.

Parameter

Waketime(typical)

CBTmin

Differencebetween CBTmin andwaketime

Table1: MetricsderivedfromDaysimeterdataforsubjectsAandB.

thedifferencebetweenthe CBTmin and waketimewasabout3hforbothsubjects,avaluenotunlikethatfoundinother studiesforentrainedindividuals(Carrier etal.,1999).Naturally,however,thephasorangles,whichindicatetherelativeoffsetbetweenthelight-darkcycleandthe activity-restcycle(Reaetal.,2008),ofthe twosubjectswerequitedifferent,consistentwiththeir CBTmin valuesandtheir larkandowlcategorizations.

Althoughphasormagnitudesandangles dependuponthesynchronybetweenthe 24-hlight-darkandactivity-restpatterns, irrespectiveofabsolutelevelsofCSandAI, itisimportanttonotethattheaveragedaily CSandAIlevelsarebothquitesimilarfor thetwosubjects.Further,theCSandAI levelsforthesetwosubjectsarelikethose forsubjectsfromothersimilarstudies(e.g., Figueiroetal.(2012)).Moreover,theiraverageCSlevelsaretypicalofsubjectswho spendmostoftheiractivehoursinindoor spaces(Figueiroetal.,2019;Figueiroet al.,2020).Whatismore,itisnoteworthy thattheirdaytimeCSlevels,presumably associatedwithcommercialworkspaces, arehigherthanthoseassociatedwiththeir eveninglightlevels,presumablyassociatedwithresidences(Reaetal.,2020).

Again,thisdifferencebetweendaytime andeveningCSlevelsistypicalofsubjects fromotherstudies.Thegrey-valuegradientin Figure 1BillustratesCSlevelsthat wouldlikelybeexperiencedoutdoorsat night,indoorsatnight,indoorsduringthe day,andoutdoorsduringtheday.TheaverageCSlevelsduringdaytimeandduring eveningfrom Figure 3Aand Figure 3B are,aswouldbeexpected,consistent withthenominalcategoriesillustratedin Figure 1B.

DaystoRe-entrainment (DTR)

Aspreviouslynoted,theCS-oscillator modelpermitsestimationsof CBTmin clocktimefromasubject’sdaily(24-h) personallight-darkexposureprofiles(measuredintermsofCS),likethoseshown in Figure 3Aand Figure 3B. CBTmin is bothaninputtotheCS-oscillatormodel andanoutputfromthemodel.Tobegin theprocessofestimating CBTmin,aninitialestimatedvalueof CBTmin isentered intothemodelalongwiththepersonal light-darkexposurepatternrepresenting several(inthisstudy,seven)24-hdaysof time-serieslightexposuredataforanindi-

vidual.TheCS-oscillatormodelcalculates theindividual’snew CBTmin clocktime basedonthelightexposureprofile,toa precisionof0.01h.Toidentifyanindividual’sbaseline CBTmin time,assuming acontinuousseven-dayweeklylightexposureprofilethatrepeatsindefinitely,the CS-oscillatormodelisruniterativelyusingthecalculated CBTmin timefromthe previousrunasitsinput,untiltheresulting CBTmin timedoesnotchangewithin 0.01h.

Forthere-entrainmentanalyses,theinitial CBTmin valuewastheasymptotic CBTmin forthebaselineperiod,then shiftedby1htorepresenttheimmediateclock-timeshiftassociatedwiththe transitiontoorfromDST.Severaliterationsofthemodelcalculationswerethen conductedwiththesameseven-daylightdarkexposurepattern.Aftereachiteration,anew CBTmin valuewasoutput fromthemodel,representingthe CBTmin timeresultingfromthepreviousestimated CBTmin valueandthelight-darkexposurepattern.Theresulting CBTmin is thenenteredintothemodelagainand,usingthesamelight-darkexposurepattern, thenext CBTmin isoutput.Eventually, theestimated CBTmin wouldreachan asymptoticvalue.

Asanexampleofthisprocess,thesolid linein Figure 4 showshow CBTmin wouldchangeduringaseriesofmodel iterationswhenclocktimehadbeenadvanced1h(∆=60min)aswouldoccurin thespringfollowingthetransitionfromST toDST.ToestimatetheDTRfollowinga timechangeinthespringandintheautumn,acriterionshiftin CBTmin of50 min(∆=50min)wasselectedforallmodel iterationsinthepresentstudy.Thiscriterionwasselectedforthreereasons;first, becauseasshownin Figure 4,ashiftapproaching60mincantakeasmuchas threetimeslongertoachievethanashiftof 50min.Second,theCS-oscillatormodel’s precisionlevelof0.01h,whilemathematicallyaccurate,isnotnecessarilyaccurate inreal-worldconditionswhereotherfactors suchasdiet(Potteretal.,2016)orexercise(Youngstedtetal.,2019)caneffect smallchangesincircadianphase.Third,as asymptoticmodelpredictionscanbeunreliable(Sandbergetal.,2021),anda50-min criterionshiftisclosetotheinflectionpoint ofthere-entrainmentcurvein Figure 4 whereitchangesfromverysteeptonearly flat,usingthiscriterionprovidesamorereliableestimateoftherelativetimeneeded tore-entrainfollowingDST-relatedtransitions.Intheexampleshownin Figure 4, theDTRisequaltoninedays.Thebaseline,orinitial, CBTmin forbothsubjects,

basedstrictlyupontheirpersonallight-dark exposurepattern,isshownin Table 1

InestimatingDTR,weexplicitlyassumed thattheactivity-restpatternwouldbe governedbythelocalclocktimeforthe twoworkingsubjectswithoutregardtoa changeinlocaltimefromSTtoDST,and viceversa(e.g.,peoplemustgettowork atthesameclocktimebeforeandafter aseasonalchangeinlocaltime).Further, becausethesetwosubjectswere(presumably)exposedonlytoindoorlighting therelationshipbetweentheactivity-rest patternandthelight-darkpatternwould alwaysremainthesame.Thus,intermsof localclocktime,therelationshipbetween theirsleeptime,includingbedtime,midsleep,andwaketime,andtheirpersonal light-darkexposurepatternwouldremain unchanged.

Todeterminetheeffectsoftheinstantaneouschangeinlocalclocktimefrom STtoDSTandfromDSTtoST,wereassignedtheprevious CBTmin value (e.g.,04:00)tothenew CBTmin after thetransition,whichwouldbe1hlater (e.g.,05:00)inthespringand1hearlier (e.g.,03:00)intheautumnwithrespectto thelocalclocktimepriortotheclocktime change.Thisplacesthebaselineestimated CBTmin fromtheCS-oscillatormodel atoddswiththenew,shifted CBTmin Again,keepingtherelationshipbetween light-darkpatternandtheactivity-restpatternfixedbeforeandaftertheshiftinlocal clocktime,wewerethenabletodeterminehowmanyiterativecycles,ordays,it wouldtakefor CBTmin toreachthe50mincriterionshifttothenewlocalclock time.Inotherwords,wewereabletodeterminehowlongitwouldtaketoreturn tothesametemporaldifferencebetween CBTmin andlocalclockwaketimeasbe-

forethechangeinlocaltime;thisdifference wasapproximately3hforbothsubjects (Table 1).

Forouranalyseswefurtherassumedthat thetwosubjectseitherresided/worked inBoston,neartheeasternborderofthe EasternTimeZone,orinDetroit,atasimilarlatitudebutnearthewesternborderof theEasternTimeZone,wheresunriseis50 minlater.

Results

DTRWithoutLight Intervention

Thebaseline CBTmins priortothechange inlocaltimeandthe CBTmins afterthe changeinlocaltimeandtheresultingpredictedDTRsforBostonandforDetroit weredeterminedforbothsubjects.Since thesetwosubjectsonlyexperiencedindoor lighting,the50-mindifferenceinsunrise had,asexpected,littleornoeffectonDTR forboththelarkandtheowl.Giventheir personallight-darkexposurepatternswere different,however,itwouldtaketheowl longerthanthelarktore-entraintothetime changes,bothinthespringandintheautumn(Table 2).

Asnotedinthe“GoalofthePresentStudy”, ourprimarygoalinthisstudywastoexploretheimpactofdifferentpracticallight interventionsthatmightbetakenbylarks andorowlsfollowingthechangefromST toDST,andviceversa,todetermineifand howDTRcouldbereduced,therebyminimizingthedurationofcircadiandisruption duetothesuddenchangeinlocalclock time.Threepresumablypracticalcalibrated

Figure4: Illustrationofthepredictedchangein CBTmin (Reaetal.,2022),representedbytheheavyblack line,forsubjectAfollowingthetransitiontoDST.

lightinterventionswereselectedformodelingwiththeCS-oscillatormodel.Each lightinterventionwasaddedtothelightdarkprofilesin Figure 3Aand Figure 3B, quantifiedintermsoftheamount(CS)and duration(hours)andbythelocaltimeit wasapplied.Itshouldbeemphasizedthat theseinterventionsareintendedtobecarriedoutafterthetransitiontoDSTorST andwouldbeexpectedtoceaseonce re-entrainmentwasestablished.Anunchangedindoorbehavioralprofilebefore andafterthetransitionwillensurecontinualentrainmentofthestabilizedcircadian phasetotheoriginal,unchanged,lightexposureprofile.

DTRWithLightIntervention

Self-luminousDisplay

Arecentmeta-analysisinvestigatingchanges inscreentimefollowingtheCOVID-19pandemicrevealedthatleisure(non-work/nonacademic)screentimehasincreasedby 0.7hperdayinadults(Trottetal.,2022). Severalstudieshavecharacterizedlightexposuresattheeyefromself-luminousdisplays.Forinstance,Gringrasetal.(2015) reportedthatsmartphones(iPhone5S,AppleInc.,Cupertino,CA,US)candelivera lightlevelof51lxattheeyewhenoperated fromatypicalreadingdistanceofabout 22.5cm.Fortypicalself-luminousspectra,thiswouldtranslateintoaCSvalue of0.12.Withregardtoself-luminousdisplays,Woodetal.(2013)andNagareet al.(2019a)havereportedthatiPads(iPad Air2andiPad2,respectively,AppleInc., Cupertino,CA,US)deliveraround70lxat theeyeforanaverageviewingdistanceof 30.5cm,oraCSof0.13.Forthisvirtual intervention,itwasassumedthatboththe larkandtheowlviewedaself-luminous display(CS=0.13)for30minbeginning at19:00,arounddinnertime.Forthetwo profilesunderinvestigationinthispaper, thisclocktimecorrespondstotheendof higherinteriorlightlevelexposures(e.g., thosefromtheworkplaceduringtheday) andthebeginningoflowerinteriorlight levelexposures(e.g.,thosefromtypicalof aresidenceindoors)(Rea,2000).

TriptoFlorida

ItisnotuncommonforpeopleinBoston andinDetroit,havingapproximatelythe samenorthlatitude(42°N),tovacation inMiami,whichisinthesametimezone butmuchfurthersouth(28°N)duringthe coldermonths.InMarchduringthechange inlocalclocktime,thedaylengthsinall threecitiesareapproximately12h.In November,duringthischange,theday lengthsareslightlyshorter(10h)inthe northerncitiesthaninMiami(11h).One

Table2: Daystore-entrainment(DTR)forthelarkandtheowlfollowingthetransitionsbetweenDSTand ST,withnochangeinlight-darkexposureprofilesrelativetoclocktime.

Table3: Daystore-entrainment(DTR)forthelarkandtheowlfordifferentpost-transitioninterventions.

wouldexpectthetimespentoutdoorsin Miamiwouldbelongerthanitwouldbe inBostonandDetroitbecauseofwarmer weather,particularlywhenapersonison vacation.Forthisvirtualintervention,itwas assumedthatthelarkandtheowlresiding inBostonandthelarkandtheowlresiding inDetroitbothflewtoMiamitheSaturday eveningoftheclockchangeinspringand autumn.Theythenspentthenextweek outdoorsinbrightdaylight.Forthisvirtual interventionitwasassumedthatthelark andtheowlkeptthesameactivity-restcycletheyhadexhibitedintheirrespective cities.Becausetheowlwouldgetupwell pastsunrise,however,thedurationoftheir daylightexposurewouldnaturallybeless (9h)thanitwouldbeforthelark(11h). Tosimulatethelightlevelstheywouldexperiencewhileoutdoorsindaylight,the recorded CLA lightexposureprofiles (forthedaylighthours)in Figure 3Aand Figure 3Bwereallmultipliedbyafactorof 10,arepresentativemultiplierforoutdoor versusindoorlightexposuresformanyindividuals(Rea,2000).

MorningWalk

Recentstatisticssuggestthatabout49 millionpeopleintheU.S.reportedengaginginrunningandjoggingactivitiesin2021 (Statista,2024).Anevengreaternumber ofpeople(115million)reportedengaging inwalkingforfitnessactivitiesduringthe sameyear.Infact,thephysicalactivity guidelinesfromtheAmericanHeartAssociationrecommendatleast150minofmoderateintensityaerobicactivityperweek(> 30minperweekday)toimprovehealthand well-being(AmericanHeartAssociation, 2024).Ithasbeenwell-documentedthat evenoncloudydays,daylightcandeliver veryhighlightlevelsattheeye(CS≥0.5). Forthisvirtualintervention,itwasassumed thatthelarkandtheowlwentforanout-

door(CS=0.5)morningwalkfor45min, 30minafterwaking.

Theresultsofthethreeinterventionsimulationsareshownin Table 3.Insome casesin Table 3,anasterisk(*)indicates whentheinterventionshiftedtheindividual inthewrongdirectionfortheDST-related transitioninclocktime(e.g.,whenaninterventioncausedaphaseadvancebutthe DST-relatedtransitioncalledforaphase delay).TheDTRsinbothBostonandDetroitwerethesameforthesevirtuallight interventions.(AseparatevirtuallightinterventioncomparingBostonandDetroit isdiscussedlatertoillustratehowalater sunriseinDetroitwouldaffectpredicted changesincircadianphase.)Ofparticular interest,theDTRvaluesin Table 3 show thatthesameinterventioncanproduce verydifferentoutcomesdependingupon theseasonwhenthelocaltimechange occurred.Asaprimeexample,a45-min morningwalkinthespringacceleratesreentrainmentbecauseitprovidesbrightlight exposuretoadvancecircadianphase,but thatsamewalkintheautumnpreventsreentrainmentbecauseitiscountertoone wantingtodelaycircadianphase.

Itisalsointerestingtoconsiderlightat nightbytheeveningself-luminousdisplay exposure.Thishasnoeffectontheowl becausethetimingofthelightexposureis wellbeforetheir CBTmin andoutsideboth thedelayandadvancephaseresponse tolight(see Table 2).However,thesame eveninglightexposurehasaprofoundeffectonthelarkbecause,again,thetiming ofthelightexposureisduringthedelay phaseresponsetolightandclosertotheir CBTmin

Asalreadynoted,thesevirtuallightinterventionshadlittleornodifferentialeffect betweenBostonandDetroitforthemorningwalkorfortheeveningself-luminous display.Thereasonisthatthesetwolight interventionssimulatedheredidnotdifferentiallyinfluenceDTRbecausetheywere notdifferentiallyexposedtodaylight.The self-luminousdisplayexposureinboth BostonandDetroitwasneveraccompaniedbydaylightbecauseitwasviewed indoorsandthemorningwalkersinboth DetroitandBostonwereoutsideaftersunrise.Supposethemorningwalkswere takenbythelarkimmediatelyafterwaking duringthespringtime,ratherthan30min afterwaking(whichresultedinaDTRof6 daysaccordingto Table 3).Inthiscase, theearlierexposuretodaylightduringthe walkinBostonwouldhaveadvantagedthe larkinBoston(reducingDTRfrom6to5 days).However,becausethesunwould nothaveriseninDetroitatthesameclock time,theearlierwalkwoulddisadvantage thelark(increasingDTRfrom6to9days). Fortheowl,thereislessdifferencebecausethesunhasalreadyrisenbythetime theowlwakesup,regardlessoflocation withinthetimezone.

Discussion

Therehasbeenagreatdealofdiscussion amongpoliticians,bureaucrats,andthe publicaboutthewisdomofpreserving oreliminatingDST.Somepeoplevoicea preferenceforSTallyearlongwhileothers prefertohaveDSTthroughouttheyear. Others,perhapsthemajority,likethefact thattherearetwoyearlychangesinlocal clocktimesothat,withrespecttolocal clocktime,theycancommutetoworkin daylightduringthewinterandcanenjoy daylightonthepatioorinthebackyard duringthesummer(Cooganetal.,2022).

Manychronobiologistsdonotliketheseasonalchangesinlocaltimebecausemost

peoplelivebylocalclocktime,notbiologicaltime.Thiscancreateasuddenchange inthelight-darkexposurecyclerelative toclocktimewhichgovernstheactivityrestcycle.Chronobiologistsknowthatthis suddendisparitybetweenclocktimeand biologicaltimecreatescircadiandisruptionwhichhasbeenlinkedtopoorsleep (Harrison,2013),accidents(Sullivanand Flannagan,2002;Lahtietal.,2010),and evenmortality(PoteserandMoshammer, 2020).Asaresult,manychronobiologists havearguedfordiscontinuationoftheseasonalchangesinlocaltime,oftenfavoring SToverDST.

TheanalysesperformedforthisstudysuggestthatDTRfollowingachangeinlocal timecanbeacceleratedorprolongedindefinitelydependinguponthelight-dark exposurecycle.Theheuristicthatlightcan bothdelayandadvancecircadianphase iscertainlynotnew,butwhatisnewis thepotentialoftheCS-oscillatormodel toquantitativelyguideindividualsexperiencingachangeinlocaltimesothatthey canminimizeDTRandthusminimizethe durationofcircadiandisruption,basedon thechronotypeandlifestyle.Itisimportant toconsider,ataminimum,anindividual’s chronotype(i.e.,owlvs.lark)becausethe analysesheredemonstratethatdifferent chronotypeswillresponddifferentlytointerventionslikethosediscussedinthis paper.Becauseofthis,someadvicegiven tothegeneralpopulation(e.g.,“getdaylightexposureinthemorning”(Suni,2024)) maynotalwaysbeapplicableorbeneficial forre-entrainmentafterST/DSTtransitions.

Directionally,everyoneknowsthatthebiologicalclockmust,withrespecttothenew localclocktime,advanceinthespringand delayintheautumn.Everyonealsoknows thatre-entrainmentofthebiologicalclock tothenewclocktimeisnotinstantaneous. Theexactnumberofdaystore-entrain hasnotbeenclear;somehavereported thetimetore-entrainissevendays(Monk

Figure5: Qualitativeimpactsofthethreeinterventions(withtimingnote,whereapplicable)forlarksand owlsimmediatelyaftertheautumnandspringDST/STtransitions:self-luminousdisplay(A),triptoFlorida (B),morningwalk(C).

andFolkard,1976),butotherssayitcan beaccomplishedintwodays(Lahtietal., 2010).Thepresentstudysuggeststhat “doingnothingdifferent”afterthelocal clocktimechangerequires10to15days forre-entrainment.Twothingsshouldbe madeclearaboutthisexercise.First,the modeledquantitativepredictionsarejust that,predictions.Theyareofferedhere baseduponthelatestscience,butanyand allpredictionsareandshouldbesubject toempiricalhypothesistesting.Thesepredictionsareonlyasgoodastheaccuracy ofinformationwithinthethreedomains describedinthe“Introduction”(theretinal responsetolight,ambulatorylightdataand theresponseofthebiologicalclock).Withoutthatinformationitwouldbedifficultto predictthemagnitudeoreventhedirection thatachangeinthelight-darkcyclemight drivethebiologicalclock.

Second,althoughweselectedtworealexamplesofdailylightprofilesandlife-style activitypatternsforanalysis,thegeneralizabilityofthepredictionsforallpeopleis limited.Thetwosubjectsthatweselected wereoneswhohadlimitedexposureto daylight.Thisseemedreasonablesincethe largemajorityofhumanactivityiscarried outindoors(Cox-GanserandHenneberger, 2021).Thesedatawerealsocollected followingtheworldwideCOVID-19pandemicandmayreflectagreaterlikelihood thanbeforetostayindoorsathome(Gold, 2023).Wemodifiedthesetwoactuallightdarkprofilestodeterminehowadditional, virtual,“practical”lightinterventionsmight affectpredictionsofthedirectionofcircadianshiftandthetimetore-entrainment. Weheldlifestyleactivitypatternsconstant assumingthatpeople’sworkandsocial activitiesaregovernedmainlybythelocal time,notbiologicaltime.Thereareliterallyaninfinitenumberofdailylightprofiles anddailylifestyleactivitypatternsthatare possibletomodel,includingspecialones likethoseexperiencedbyfarmers(bright lightallday),computeranalysts(dimlight allday),flightattendants(non-24-hlight exposures),andfirefighters(shiftworkers).Thetwoprofilesweusedinthispapercouldnotpossiblybeindicativeofthe entireWesternpopulation,buttheyare typicalof“morning”(lark)and“evening” (owl)types(Lacketal.,2009).Still,there isagreatdealmore“custom”workthat needstobeundertakentopredicthelpful, individualizedlightinterventions,including betterunderstandingtheslowercircadian adaptationofolderadults(Costa,2003) andthosewithlargecircadianrhythmamplitudes(Reinbergetal.,1978).Wehope, however,thattheCS-oscillatormodelcan beausefultoolforenhancingourunderstandingoftheseandrelatedfactors.

Notwithstanding,andassumingthatour twocasesarenotoutliers,theguidancein Figure 5 isofferedas“extendedheuristics” tosuggestlightinterventionsthatmight helpwiththespringandautumnchanges inlocalclocktime.Thegreenandredhues representthedirectionofphasechangeinducedbythelightinterventionwithrespect tothegoal,eitheradvanceordelay.The huesaturationrepresentsthemagnitude ofthedirectioninducedbythelightintervention.Aspreviouslymentioned,these threeextendedheuristicinterventionsare meanttobetemporary,onlyoccurring afterthetransitiontoDSTortoSTuntilreentrainmentisachieved.Further,basedon theunderlyinglightexposureprofileswe evaluated,thepredictionsdescribedhere applytoindividualswhoareprimarilyexposedtoindoorlighting,alargefractionof thepopulation.

Conclusion

TheCS-oscillatormodel(Reaetal.,2022) usedinthepresentstudyprovides“extendedheuristics”thatprobablycanhelp peoplecopebetterwiththetwice-seasonal changesinlocaltimeassociatedwithDST. Whereasthesetwice-seasonalchanges inlocaltimeaffectnearlyeveryone,their negativeimpactonthecircadiansystem isprobablysmallwithrespecttothose inducedbyirregularlightexposuresexperiencedbyindividualswhoengageinshift workorfrequentairtravelacrossmultiple timezones.TheCS-oscillatormodelispotentiallyimportantfordevelopingstrategies tominimizecircadiandisruptioninthese particularlyvulnerablepopulations,butthe model’spredictionsneedtobeverified empiricallyandextendedtomoreextreme chronotypesandtoshiftworkersbefore formalimplementation. ■

Abbreviations

AI:Activityindex

CBTmin:Corebodytemperatureminimum

CIE:CommissionInternationaledel’Éclairage

CLA:Circadianlight

CS:Circadianstimulus

DST:Daylightsavingtime

DTR:Daystore-entrainment

ipRGC:Intrinsicallyphotosensitiveretinal ganglioncell

MAE:Meanabsoluteerror

RHT:Retinohypothalamictract

RMS:Rootmeansquare

SCN:Suprachiasmaticnuclei

ST:Standardtime

ConflictofInterest

Theauthorsdeclarethattheresearchwas conductedintheabsenceofanycommercialorfinancialrelationshipsthatcouldbe construedasapotentialconflictofinterest.

AuthorContributions

MSR:conceptualization,formalanalysis, investigation,methodology,projectadministration,supervision,validation,visualization,writing(originaldraft,review, andediting).RN:conceptualization,data curation,formalanalysis,investigation, methodology,resources,software,validation,visualization,writing(originaldraft, review,andediting).JDB:Formalanalysis,investigation,validation,visualization, writing(originaldraft,review,andediting). MGF:conceptualization,fundingacquisition,methodology,projectadministration, supervision,validation,writing(reviewand editing).Allauthorsareaccountableforthe contentofthework.

Funding

Theauthorsdeclarefinancialsupportwas receivedfromNationalInstituteonAginggrants5R44AG060857(MSR,RN, JDB,MGF)and5R01AG034157(MSR, RN,JDB,MGF)fortheresearch,authorship,andpublicationofthisarticle.The developmentoftheCS-oscillatormodel usedinthispaperhadbeensponsored bytheArmyResearchOffice,contract W911NF2110183(MSR,MGF).

Acknowledgments

TheauthorswishtoacknowledgeAndrewBierman,whodevelopedthebasic codefortheCS-oscillatormodel.This articlewasoriginallypublishedinFrontiersinPhotonics,vol.5,2024, https: //doi.org/10.3389/fphot.2024.1386703; (CC-BY4.0).

DataAvailabilityStatement

Thedataanalyzedforthestudywillbe madeavailablebythecorrespondingauthoronreasonablerequest.

References

• AmericanHeartAssociation(2024).AmericanHeart AssociationRecommendationsforPhysicalActivityin AdultsandKids[Online].Dallas,TX:AmericanHeart Association.Available: https://www.heart.org/en/hea lthy-living/fitness/fitness-basics/aha-recs-for-physica l-activity-in-adults (Accessed8February2024).

• Appleman,K.,Figueiro,M.G.,andRea,M.S.(2013). Controllinglight-darkexposurepatternsratherthan sleepschedulesdeterminescircadianphase.Sleep Med.14,456-461.doi:10.1016/j.sleep.2012.12.011

• Aschoff,J.(1965).CircadianClocks:Proceedingsof theFeldafingSummerSchool,7-18September1964. Amsterdam:North-HollandPublishingCompany.

• Barlow,H.B.(1972).”DarkandLightAdaptation: Psychophysics,”inVisualPsychophysics,eds.M. Alpern,E.Aulhorn,H.B.Barlow,E.Baumgardt,H.R. Blackwell,D.S.Blough,etal.(Berlin,Heidelberg: SpringerBerlinHeidelberg),pp.1-28.

• Bierman,A.,Klein,T.R.,andRea,M.S.(2005).The Daysimeter:Adeviceformeasuringopticalradiation asastimulusforthehumancircadiansystem.Meas. Sci.Technol.16,2292-2299.doi:10.1088/09570233/16/11/023

• Bonmati-Carrion,M.A.,Arguelles-Prieto,R.,MartinezMadrid,M.J.,Reiter,R.,Hardeland,R.,Rol,M.A.,et al.(2014).ProtectingtheMelatoninRhythmthrough CircadianHealthyLightExposure.Int.J.Mol.Sci. 15,23448-23500.doi:10.3390/ijms151223448

• Carrier,J.,Monk,T.H.,Reynolds,C.F.,Buysse,D.J., andKupfer,D.J.(1999).Areagedifferencesinsleep duetophasedifferencesintheoutputoftheorcadiantimingsystem?Chronobiol.Int.16,79-91. doi:10.3109/07420529908998714

• CommissionInternationaleDeL’éclairage(1926). CommissionInternationaledel’ÉclairageProceedings,1924.Vienna:CommissionInternationalede l’Éclairage.

• Coogan,A.N.,Richardson,S.,andRaman,S. (2022).Adata-informedperspectiveonpublic preferencesforretainingorabolishingbiannual clockchanges.J.Biol.Rhythms37,351-357. doi:10.1177/07487304221096390

• Costa,G.(2003).Factorsinfluencinghealthof workersandtolerancetoshiftwork.Theor.IssuesErgonomicsSci.4,263-288.doi:10.1080/ 14639220210158880

• Cox-Ganser,J.M.,andHenneberger,P.K.(2021). Occupationsbyproximityandindoor/outdoorwork: RelevancetoCOVID-19inallworkersandBlack/Hispanicworkers.Am.J.Prev.Med.60,621-628. doi:10.1016/j.amepre.2020.12.016

• Delean,A.,Munson,P.J.,andRodbard,D.(1978). Simultaneousanalysisoffamiliesofsigmoidalcurves: Applicationtobioassay,radioligandassay,andphysiologicaldose-responsecurves.Am.J.Physiol.235, E97-102.doi:10.1152/ajpendo.1978.235.2.E97

• Evans,L.S.,Peachey,N.S.,andMarchese,A.L. (1993).Comparisonofthreemethodsofestimating theparametersoftheNaka-Rushtonequation.Doc. Ophthalmol.84,19-30.doi:10.1007/BF01203279

• Figueiro,M.G.,Hamner,R.,Bierman,A.,andRea, M.S.(2013).Comparisonsofthreepracticalfield devicesusedtomeasurepersonallightexposures andactivitylevels.LightingRes.Technol.45,421434.doi:10.1177/1477153512450453

• Figueiro,M.G.,Kalsher,M.,Steverson,B.C.,Heerwagen,J.,Kampschroer,K.,andRea,M.S.(2019). Circadian-effectivelightanditsimpactonalertnessin officeworkers.LightingRes.Technol.51,171-183. doi:10.1177/1477153517750006

• Figueiro,M.G.,Plitnick,B.,andRea,M.S.(2014).The effectsofchronotype,sleepscheduleandlight/dark patternexposuresoncircadianphase.SleepMed. 15,1554–1564.doi:10.1016/j.sleep.2014.07.009

• Figueiro,M.G.,Rea,M.S.,andHamner,R.(2012). ”Calibratedpersonallightexposuresastheymight affectmelatoninsuppressionindifferentpopulations,” inProceedingsofExperiencingLight2012,Eindhoven,NL,12-13November2012.(Eindhoven,NL: EindhovenUniversityofTechnologyLibrary).Available:http://www.2012.experiencinglight.nl/doc/9.pdf

• Figueiro,M.G.,Steverson,B.,Heerwagen,J., Yucel,R.,Roohan,C.,Sahin,L.,etal.(2020). Light,entrainmentandalertness:Acasestudy

inoffices.LightingRes.Technol.52,736-750. doi:10.1177/1477153519885157

• Gale,C.,andMartyn,C.(1998).Larksandowlsand health,wealth,andwisdom.BMJ317,1675-1677. doi:10.1136/bmj.317.7174.1675

• Gold,J.2023.CovidHasTurnedManyHomeowners IntoHomebodies,NewSurveyReveals.Forbes [Online].Available: https://www.forbes.com/sites/jam iegold/2023/04/25/covid-has-turned-many-homeo wners-into-homebodies-new-survey-reveals/?sh=2 da4a57b63d0 (Accessed8February2024).

• Gringras,P.,Middleton,B.,Skene,D.J.,andRevell, V.L.(2015).Bigger,brighter,bluer-better?Current light-emittingdevices-adversesleeppropertiesand preventativestrategies.Front.PublicHealth3,233. doi:10.3389/fpubh.2015.00233

• Harrison,Y.(2013).Theimpactofdaylightsaving timeonsleepandrelatedbehaviours.SleepMed. Rev.17,285-292.doi:10.1016/j.smrv.2012.10.001

• Huang,Y.,Mayer,C.,Cheng,P.,Siddula,A., Burgess,H.J.,Drake,C.,etal.(2021).Predicting circadianphaseacrosspopulations:Acomparisonof mathematicalmodelsandwearabledevices.Sleep 44.doi:10.1093/sleep/zsab126

• Jansen,J.,andHalbertsma,N.A.(1951).Collection ofProceedingsandReportofSessions,TwelfthSessionoftheInternationalCommissiononIllumination, Stockholm,JuneandJuly,1951.NewYork:Bureau CentraldelaCIE.

• Kronauer,R.E.(1990).”Aquantitativemodelfor theeffectsoflightontheamplitudeandphaseof thedeepcircadianpacemaker,basedonhuman data,”inSleep‘90,Proceedingsofthe10thESRS Congress,ed.J.Horne.1sted.(Bochum,Germany: PontenagelPress),pp.306-309.

• Kronauer,R.E.,Forger,D.B.,andJewett,M.E.(1999). Quantifyinghumancircadianpacemakerresponse tobrief,extended,andrepeatedlightstimulioverthe phototopicrange.J.Biol.Rhythms14,500-516. doi:10.1177/074873049901400609

• Lack,L.,Bailey,M.,Lovato,N.,andWright,H. (2009).Chronotypedifferencesincircadianrhythms oftemperature,melatonin,andsleepinessasmeasuredinamodifiedconstantroutineprotocol.Nat. Sci.Sleep.1,1-8.doi:10.2147/nss.s6234

• Lahti,T.,Nysten,E.,Haukka,J.,Sulander,P.,and Partonen,T.(2010).Daylightsavingtimetransitions androadtrafficaccidents.J.Environ.PublicHealth 2010,657167.doi:10.1155/2010/657167

• Meir,R.(2002).Managingtransmeridiantravel: Guidelinesforminimizingthenegativeimpact ofinternationaltravelonperformance.Strength Cond.J.24,28-34.doi:10.1519/1533-4295(2002) 024<0028:MTTGFM>2.0.CO;2

• Miller,B.H.,andTakahashi,J.S.(2014).Centralcircadiancontroloffemalereproductivefunction.Front. Endocrinol.(Lausanne)4.doi:10.3389/fendo.2013.00195

• Miller,D.,Figueiro,M.G.,Bierman,A.,Schernhammer,E.,andRea,M.S.(2010).Ecologicalmeasurementsoflightexposure,activityandcircadian disruption.LightingRes.Technol.42,271-284. doi:10.1177/1477153510367977

• Monk,T.H.,andFolkard,S.(1976).Adjustingtothe changestoandfromDaylightSavingTime.Nature 261,688-689.doi:10.1038/261688a0

• Mott,C.,Dumont,G.,Boivin,D.B.,andMollicone,D. (2011).Model-basedhumancircadianphaseestimationusingaparticlefilter.IEEETrans.Biomed.Eng. 58,1325-1336.doi:10.1109/TBME.2011.2107321

• Nagare,R.,Plitnick,B.,andFigueiro,M.G.(2019a). DoestheiPadNightShiftmodereducemelatonin suppression?LightingRes.Technol.51,373-383. doi:10.1177/1477153517748189

• Nagare,R.,Plitnick,B.,andFigueiro,M.G.(2019b). Effectofexposuredurationandlightspectraon nighttimemelatoninsuppressioninadolescents andadults.LightingRes.Technol.51,530-540. doi:10.1177/1477153518763003

• Nagare,R.,Rea,M.S.,Plitnick,B.,andFigueiro,M.G. (2019c).Effectofwhitelightdevoidof“cyan”spectrumradiationonnighttimemelatoninsuppression overa1-hexposureduration.J.Biol.Rhythms34, 195-204.doi:10.1177/0748730419830013

• Nagare,R.,Rea,M.S.,Plitnick,B.,andFigueiro, M.G.(2019d).Nocturnalmelatoninsuppressionby adolescentsandadultsfordifferentlevels,spectra,

anddurationsoflightexposure.J.Biol.Rhythms34, 178-194.doi:10.1177/0748730419828056

• Poteser,M.,andMoshammer,H.(2020).Daylightsavingtimetransitions:Impactontotalmortality.Int.J.Env.Res.PublicHealth17,1611. doi:10.3390/ijerph17051611

• Potter,G.D.M.,Cade,J.E.,Grant,P.J.,andHardie, L.J.(2016).Nutritionandthecircadiansystem.Br.J. Nutr.116,434-442.doi:10.1017/S0007114516002117

• Qin,L.-Q.,Li,J.,Wang,Y.,Wang,J.,Xu,J.-Y.,and Kaneko,T.(2003).Theeffectsofnocturnallifeonendocrinecircadianpatternsinhealthyadults.LifeSci. 73,2467-2475.doi:10.1016/S0024-3205(03)006283

• Rea,M.S.(ed.).(2000).TheIESNALightingHandbook:ReferenceandApplication.NewYork:IlluminatingEngineeringSociety.

• Rea,M.S.(2012).ValueMetricsforBetterLighting. Bellingham,WA:SPIEPress.

• Rea,M.S.,Bierman,A.,Figueiro,M.G.,andBullough, J.D.(2008).Anewapproachtounderstandingthe impactofcircadiandisruptiononhumanhealth.J. CircadianRhythms6,7.doi:10.1186/1740-3391-6-7

• Rea,M.S.,Figueiro,M.G.,Bierman,A.,andBullough, J.D.(2010).Circadianlight.J.CircadianRhythms8, 2.doi:10.1186/1740-3391-8-2

• Rea,M.S.,Nagare,R.,Bierman,A.,andFigueiro, M.G.(2022).Thecircadianstimulus-oscillator model:ImprovementstoKronauer’smodelofthe humancircadianpacemaker.Front.Neurosci.16. doi:10.3389/fnins.2022.965525

• Rea,M.S.,Nagare,R.,andFigueiro,M.G.(2021a). Modelingcircadianphototransduction:Quantitative predictionsofpsychophysicaldata.Front.Neurosci.15,10.3389/fnins.2021.615322.doi:10.3389/ fnins.2021.615322

• Rea,M.S.,Nagare,R.,andFigueiro,M.G.(2021b). Modelingcircadianphototransduction:Retinalneurophysiologyandneuroanatomy.Front.Neurosci. 14,10.3389/fnins.2020.615305.doi:10.3389/ fnins.2020.615305

• Rea,M.S.,Nagare,R.M.,andFigueiro,M.G.(2020). Predictionsofmelatoninsuppressionduringtheearly biologicalnightandtheirimplicationsforresidentiallightexposurespriortosleeping.Sci.Rep.10, 14114.doi:10.1038/s41598-020-70619-5

• Rea,M.S.,Plitnick,B.,andFigueiro,M.G.(2016). Effectofcustombluelightinterventionondimlight melatoninonsetinhealthyadults.Unpublishedwork. AvailablefromLightandHealthResearchCenter, IcahnSchoolofMedicineatMountSinai,NewYork.

• Refinetti,R.(2020).Circadianrhythmicityofbody temperatureandmetabolism.Temperature7,321362.doi:10.1080/23328940.2020.1743605

• Reinberg,A.,Vieux,N.,Ghata,J.,Chaumont,A.J., andLaporte,A.(1978).Istherhythmamplitude relatedtotheabilitytophase-shiftcircadianrhythms ofshift-workers?J.Physiol.(Paris)74,405-409.

• Reiter,R.J.,Tan,D.-X.,Korkmaz,A.,Erren,T.C., Piekarski,C.,Tamura,H.,etal.(2007).Lightatnight, chronodisruption,melatoninsuppression,andcancer risk:Areview.Crit.Rev.Oncogen.13,303-328. doi:10.1615/critrevoncog.v13.i4.30.

• Roenneberg,T.,Wirz-Justice,A.,andMerrow,M. (2003).Lifebetweenclocks:Dailytemporalpatterns ofhumanchronotypes.J.Biol.Rhythms18,80-90. doi:10.1177/0748730402239679

• Sandberg,A.,Armstrong,S.,Gorman,R.,andEngland,R.(2021).Sigmoidsbehavingbadly:Whythey usuallycannotpredictthefutureaswellasthey seemtopromise[Online].Rochester,NY:Social ScienceResearchNetwork–Elsevier.Available: https://ssrn.com/abstract=3926169 (Accessed16 April2024).

• Sharkey,K.M.,Carskadon,M.A.,Figueiro,M.G.,Zhu, Y.,andRea,M.S.(2011).Effectsofanadvanced sleepscheduleandmorningshortwavelengthlight exposureoncircadianphaseinyoungadultswith latesleepschedules.SleepMed.12,685-692. doi:10.1016/j.sleep.2011.01.016

• Smolensky,M.H.,Sackett-Lundeen,L.L.,andPortaluppi,F.(2015).Nocturnallightpollutionand underexposuretodaytimesunlight:Complementarymechanismsofcircadiandisruptionandrelateddiseases.Chronobiol.Int.32,1029-1048. doi:10.3109/07420528.2015.1072002

• Sullivan,J.M.,andFlannagan,M.J.(2002).Therole ofambientlightlevelinfatalcrashes:inferencesfrom daylightsavingtimetransitions.Accid.Anal.Prev. 34,487-498.doi:10.1016/S0001-4575(01)00046-X

• Suni,E.(2024).HowtoPreparefortheStartandEnd ofDaylightSavingTime[Online].SleepFoundation (SleepDoctorHoldings).Available: https://www.slee pfoundation.org/circadian-rhythm/how-to-prepare-f or-daylight-saving-time (Accessed6February2024).

• Swamy,S.,Xie,X.,Kukino,A.,Calcagno,H.E., Lasarev,M.R.,Park,J.H.,etal.(2018).Circadian disruptionoffoodavailabilitysignificantlyreduces reproductivesuccessinmice.Horm.Behav.105, 177-184.doi:10.1016/j.yhbeh.2018.07.006

• Trott,M.,Driscoll,R.,Iraldo,E.,andPardhan,S. (2022).Changesandcorrelatesofscreentime inadultsandchildrenduringtheCOVID-19pandemic:Asystematicreviewandmeta-analysis.eClinicalMedicine48,101452.doi:10.1016/j.eclinm.2022. 101452

• Tumin,R.(2023).HowtoMaketheMostofthe MorningLight.NewYorkTimes,3November2023, Availableat: https://www.nytimes.com/2023/11/03 /well/daylight-saving-tips.html.(Accessed7February 2024).

• U.S.EnvironmentalProtectionAgency(1989).AssessmentandControlofIndoorAirPollution,in:ReporttoCongressonIndoorAirQuality,vol.2.Report numberPB-90-167396/XAB;EPA-400/1-89/001C. (Washington,DC:U.S.EnvironmentalProtection Agency).

• UlStandards&Engagement(2019).DesignGuideline forPromotingCircadianEntrainmentwithLightfor Day-ActivePeople,DesignGuideline24480,Edition 1.Northbrook,IL:UnderwritersLaboratories.

• Woelders,T.,Beersma,D.G.M.,Gordijn,M.C.M., Hut,R.A.,andWams,E.J.(2017).Dailylightexposurepatternsrevealphaseandperiodofthehumancircadianclock.J.Biol.Rhythms32,274-286. doi:10.1177/0748730417696787

• Wood,B.,Rea,M.S.,Plitnick,B.,andFigueiro, M.G.(2013).Lightlevelanddurationofexposure determinetheimpactofself-luminoustabletson melatoninsuppression.Appl.Ergonomics44,237240.doi:10.1016/j.apergo.2012.07.008

• Youngstedt,S.D.,Elliott,J.A.,andKripke,D.F.(2019). Humancircadianphase–responsecurvesforexercise.J.Physiol.597,2253-2268.doi:10.1113/ JP276943

• StHilaire,M.A.,Klerman,E.B.,Khalsa,S.B.,Wright, K.P.,Jr.,Czeisler,C.A.,andKronauer,R.E.(2007). Additionofanon-photiccomponenttoalight-based mathematicalmodelofthehumancircadianpacemaker.J.Theor.Biol.247,583-599.doi:S00225193(07)00167-1[pii]10.1016/j.jtbi.2007.04.001 Statista(2024).Running&Jogging-Statistics& Facts[Online].Hamburg,DE:Statista.com.Available: https://www.statista.com/topics/1743/running-and-j ogging/#topicOverview (Accessed8February2024).

LEDLightinginHorticultural Applications–A2024Update

Prof.ErikRUNKLE,ProfessorandFloricultureExtensionSpecialist intheDepartmentofHorticultureatMichiganStateUniversity

ErikRUNKLE

ErikRunkleisprofessorandfloriculture ExtensionspecialistintheDepartmentof HorticultureatMichiganStateUniversity. Hecanbereachedatrunkleer@msu.edu. Referencetocompanies,commercialproductsortradenamesdoesnotimplyendorsementorbiasagainstthosenotmentioned.

runkleer@msu.edu

LEDshavebecomethe“goto”fixture typeformosthorticulturallightingapplications.Growersarereplacinghighpressuresodium(HPS)withLEDs,oftendeliveringahigherintensitythan before.Inaddition,newsupplemental lightinginstallationsareusuallywith LEDs.

Thereareseveralreasonsforthewidespread adoptionofLEDs,mostnotablythetechnologicaladvancesandincreasedgrower appreciationforhowlightingcanimprove cropquality,decreaseproductiontime,or both.LEDsaremuchmorecomplexthan conventionalfixturesbecausetheyvary widelyinlightoutput(intensityandspectrum),efficacy(electricalefficiency),beam angle,cost,easeofinstallation,etc.

Beforedelvingintosomeperformance characteristicsofLEDs,weneedtoensure thatfixtureshavebeendesignedtotolerategrowingconditions(forexample,high humidity)andmeetbenchmarkstandards specifictohorticulture.Tohelpaccomplish this,growersareadvisedtoconsiderLED productsthatareontheHorticulturalLightingQualifiedProductlistbytheDesignLight Consortium(DLC).Visitdesignlights.orgfor moreinformation.

Threeofthemajorwaystocharacterizean LEDfixturearelightoutput,lightspectrum andefficacy.Allthreearebasedonphotonswithinthephotosyntheticallyactive waveband(PAR;400–700nm).Thereare compellingreasonstoalsoconsiderfar-red

light,whichextendsPAR(ePAR)to750nm or800nm.

Lightoutputreferstothenumberofphotons(inmicromoles,orµmol)emittedby afixturepersecondandhasaunitof µmol·s−1.Technicallyspeaking,lightoutputisthephotonfluxofthePAR(orePAR) waveband,whichcanonlybemeasured inatestinglaboratory.Thelightspectrumreferstorelativepercentagesofblue, green,redandfar-redlight,andalthough thepeakwavelengthsarealsoimportant, theyareusuallynotreported.

TestsetupintheControlledEnvironmentLighting LabintheDepartmentofHorticultureatMichiganStateUniversity.Photocredits:ErikRunkle.

Finally,fixtureefficacyreferstothephoton fluxofafixturedividedbytheenergyconsumedtoemitthatquantityoflight.Itsunit

Table1: Thevariationinlightoutputandfixtureefficacyof15LEDfixturesontheDLCHorticulturalLightingQualifiedProductsList.LEDslistedareprimarilyfor supplementalgreenhouselightingandwerearbitrarilyselectedforillustrationpurposesonly. DatacourtesyofErikRunkle.

ismicromolesperjoule,orµmol·J−1.FixtureefficacyisusuallyreportedforthePAR waveband(photosyntheticphotonefficacy, orPPE).

“WhiletheperformancemetricsofLEDsareimportant, thereareotheraspectsthat meritconsiderationwhenselectingalightingfixture.”

ERIKRUNKLE,MICHIGANSTATEUNIVERSITY

Table 1 illustratesthevariationinlightoutput(photonflux),lightspectrum(percentageofphotonsineachoffourwavebands), andefficiency(efficacy)of15LEDfixtures ontheDLCHorticulturalLightingQualified ProductsList.Inearly2020,therewere fewerthan100qualifiedLEDproducts forhorticulture.Inearly2024,therewere around1,500.Bydesign,DLC-qualified productsareatleast35%moreefficient thanHPS.Forexample,440-WHPSlamps withamagneticballasthaveanefficacyof

0.94µmol·J−1 and1040-Wdouble-ended HPSlampswithanelectronicballasthave anefficacyof1.70µmol·J−1 basedon datafromUtahStateUniversity.

ThevastmajorityofhorticulturalLEDproductsconsistofindividualblue,whiteand/or redLEDs.Fixtureswiththehighestefficaciesusuallyemitmostlyredlight,sincered LEDsarethemostefficient.Thegreenlight percentageisrelatedtothepercentageof whiteLEDs,andthelightemittedwillappearwhiterasthepercentageofgreenlight increases.Alowgreenlightpercentage (e.g.,<15%)translatesintolightthatwill appearmorepinkorpurple.

Thereisalargevariationinphotonflux amongLEDproducts,whichmeansthefixturenumber,installationheightandspacingandlightuniformitycanvarydramatically.

Inaddition,someLEDfixtures(including threein Table 1)emitameaningfulamount offarredlight,whichcandirectlyandindirectlyincreaseplantgrowth.However, thesephotonsarenotcountedinthePAR photonfluxmeasurementsorefficacymetrics.

WhiletheperformancemetricsofLEDs areimportant,thereareotheraspectsthat meritconsiderationwhenselectingalightingfixture.Thisincludes,butisnotlimited to,product/brandreliability,customerservice,installationcost,electricrates,availabilityofenergyrebates,fixtureformfactor andeaseofinstallation. ■

Thisarticlewaspublishedundertheoriginaltitle“LEDlighting:A2024update”in theFebruary2024issueof GPNmagazine: GPN

LpSDigitalSummit&LpSAwards

LugerResearche.U./LEDProfessional

TheLpSDigitalSummittakesplace annuallyatthebeginningofDecember. Inconjunctionwiththisevent,theLpS DigitalAwardsarealsopresented.In thisarticle,weaimtoprovideyouwith moredetailedinformationaboutthe LpSSummitandtheAwards,aswell asexplainhowyoucanactivelyparticipateintheevent.

TheLpSDigitalSummitandLpSDigital AwardswilltakeplaceonDecember5, 2024.Theeventwillbeheldonline,andwill includeahalfdayofpresentations,panel discussions,andtheawardsceremony.A detailedschedulewillbereleasedcloser totheevent.Staytunedformoreupdates andmakesuretomarkyourcalendar.

AnnouncingtheLpS

DigitalSummitandLpS DigitalAwards–December5,2024

TheLpSDigitalSummitissettotakeplace on5thDecember2024,markingasignificanteventintheworldoflightingtechnology.Thisyear,theSummitwillonceagain serveasaplatformforindustryleaders, innovators,andenthusiaststoconverge, shareinsights,andexplorethefutureof lightingsolutions.Onthesameday,weare proudtohosttheprestigiousLpSDigital Awards,celebratingoutstandingachievementsandinnovationsinthefield.This dualeventoffersauniqueopportunityfor participantstoengagewithcutting-edge developmentsandhonorthepioneersof ourindustry.

SiegfriedLuger,EventOrganizer

Sponsorships

IfyouareinterestedinsponsoringtheLpS DigitalSummitortheLpSDigitalAwards andbrandingthemwithyourorganization, pleasecontactus.Wewillputtogethera promotionpackagethatwillfitallofyour requirements.

WriteUs: info@lugerresearch.com

“Joinusforaninspiring afternoononthesubjectof lighting.”

SIEGFRIEDLUGER,CEOOFLUGERRESEARCH

JoinUsattheLpS DigitalSummit–RegisterNow

LugerResearche.U.,publisherofLEDProfessional,istheorganizeroftheannual LpSDigitalSummit,whichevolvedfrom theannualsymposiuminBregenz,Austria. Thisyear’seventwilltakeplaceonlineon December5,2024.Themed“Trendsin Lighting-FocusonRelevance”,thesummitfocusesoncurrenttrendsacrossvariouslightingsectors.Apanelofrenowned expertsfromorganizations,industry,and researchwilldiscussthelatestdevelopments.Followingtheexpertdiscussions, theannualLpSDigitalAwardswillbepresented,recognizingexcellenceinproducts, systems,andsustainability.Submissions fortheawardsareopenuntiltheendof November.Theregistrationplatformforthe eventisalsoopen,andparticipationisfree ofcharge.

ProgramOutline

• Keynotes

• PanelDiscussionwithLightingExperts andParticipantsabout“TrendsinLighting-FocusonRelevance”

• AwardsCeremony

Don’tmissthechancetoparticipateinthe LpSDigitalSummit2024.Whetheryouare aseasonedprofessionaloranewcomerto theindustry,theSummitoffersvaluable insightsandnetworkingopportunities. Engagewithleadingexperts,discoverthe latesttrends,andcontributetodiscussions shapingthefutureoflightingtechnology. Registernowtosecureyourspotandbea partofthisdynamicevent.

SubmitYourInnovation fortheLpSDigital Awards

Thefollowingawardswillbebestowed:

• AchievementAwardforexceptionalcontributionsbyanindividual.

• ScientificPaperAwardforthebestscientificpaperpublishedin2024inthe LEDprofessionalReview.

• ProductAwardsforoutstandinginnovations.

• SustainabilityAwardsforproductsof specialsignificanceinsustainabilityand eco-design.

Thisyear,forthesecondtime,theAI Prizewillbealsoawarded,evaluatedby atrainedAIlightingmodelintheareasof Market&Innovation,Technology,andSustainability.

TheLpSDigitalAwardsarenowopenfor entries.Weareseekingthemostinnovativeandimpactfulcontributionstothe lightingindustry.Ifyourproject,product, orresearchhasthepotentialtorevolutionizethefield,weencourageyoutosubmit itforconsideration.Awardwinnerswillbe announcedduringtheLpSDigitalSummit. SubmityourentrybytheendofNovember andtakeyourplaceamongtheindustry’s elite.

ContactUs

FormoreinformationabouttheLpSDigital Summit,speakersubmissions,participant registration,orawardentries,pleasecontactusat

ContactUs info@lugerresearch.com

Weareheretoassistyouwithanyquestionsyoumayhave.

Bringingtogetherthebrightestmindsand mostinnovativecompaniesinthelighting industryfortheLpSDigitalSummitand Awardsisourgoalandwhatmakesus excited.Whetheryouareattendingasa speaker,participant,orawardentrant,your involvementiswhatmakesthiseventtruly special.JoinusinDecembertocelebrate innovation,shareknowledge,anddrivethe futureoflightingtechnology. ■

SubmitYourInnovation

ExpertTalksonLight–TimeMatters,ShiningLighton

MetabolicHealth

GoodLightGroup,SocietyforLightTreatmentandBiological Rhythms,theDaylightAcademy,andLugerResearch|7thEdition

Dr.CharnaDibner–

Moderation

CharnaDibnercompletedherPhDinMedicalSciencesunderthesupervisionofProfessorDaleFrankintheDepartmentof BiochemistryattheTechnionIsraelInstitute ofTechnology,headedbyNobelLaureate ProfessorAvramHershko.Shenextmoved toGenevawhereshecompletedherpostdoctoraltrainingattheFacultyofScience, UniversityofGeneva,withProfessorUeli Schibler,workingonthemechanismsof transcriptionalandtemperaturecompensationofthemammaliancircadianclocks. In2009,shewasappointedasaGroup LeaderoftheLaboratoryofCircadianEndocrinologyattheFacultyofMedicine, acquiredherPrivateDocentdegree,and wasnominatedAssociateProfessorin 2021.Herworkcentersupontheimplicationofcircadianoscillatorsinregulationof metabolicprocessesinmammals.Inparticular,sheisinterestedinintricateinterplay betweentheisletcellularclocks,andinthe inter-organdesynchronyuponmetabolic diseases,unravelingtherolesofthecircadianclocksinhumanmetabolicdiseases. Charna’sworkhasbeenawardedwith severalprestigiousSwissprizesincluding RocheResearchFoundationprize,Takeda prizefordiabetesresearch,theawardsby FrenchSwissFoundationofDiabetesResearch,andLeenaardsandISRECFoundationawardsfortranslationalresearch.

Dr.KathrynReid–

FromtheRealWorldtothe Lab:WhyLightMattersfor MetabolicHealth

Theimpactoflightisdependentupon whenitoccursrelativetotheinternalbiologicalclock,andassuchthetimingof whenwegetlightordarkacross24-hours matters.Lightexposurepatternsarea modifiablefactorthatcanhavesignificant impactonhealthandwellbeing.Results fromrealworldandlaboratory-controlled studiesthatexaminetheimpactoflightexposureonhealthwillbediscussed.From pregnantwomentoolderadults,datafrom real-worldmonitoringoflightlevelssuggeststhathigherlevelsoflightexposurein thefewhoursbeforeandduringsleepare associatedwithpoormetabolichealth.The mechanismunderlyingthesefindingsare supportedbycontrolledlaboratory-based studiesexaminingtheimpactoflighton cardio-metabolicfunction.Together,these studiessuggestthatinterventionstooptimizethepatternoflight-darkexposure acrossthe24-hourdaycouldbebeneficial tohealthinvulnerablepopulations.

Dr.Jan-FriederHarmsen–

DiabetesintheDaylight: MetabolicBenefitsThrough NaturalOfficeLighting?

Dr.Harmsentalksaboutarecentlycompletedstudywherehetestedwhethernaturaldaylightduringofficehoursismore beneficialformetabolichealthoutcomes oftype2diabetespatients,comparedto constantarticiallighting. RecordedTalk

https://bit.ly/3V5V53o

https://bit.ly/4bay5pN

youtube.com/c/LpSDIGITAL

Supportedby

DEADLINES|LpR106

ADCLOSE

November1,2024

MATERIALDUE

November1,2024

DIGITALPUBLICATION

November15,2024

PRINTPUBLICATION

November30,2024

ENQUIRIES

info@lugerresearch.com

LightingtheWayForward

InnovationsinDALI,Health,andAIDrivenControl

TheupcomingissueofLpR#106promises tobepackedwithcutting-edgeinsightsinto thefutureoflightingtechnology.Wefeature anexclusiveinterviewwithMarkMcClear, Casambi’sCEO,reflectingonhisfirst100 daysatthehelmanddiscussingthelatest innovations,particularlyinrelationtoDALI.In anotherinterview,ArnulfRuppfromtheDALI Alliancebreaksdownthefundamentalsof DALItechnologywhileexploringthenewest trendsanddevelopments,includingDALI+. AWhitePaperfromtheGoodLightGroup delvesintorecentresearchontheconnectionbetweenlightandhealth,highlighting theeconomicbenefitsofgoodlighting.We alsoexplorethefascinatingpossibilityof controllinglightingandeffectsviaanapp usingmusicmetadata,wherealgorithmscan beswappedoutwithAImodelstodetect moodsinconversationsandadjustlighting accordingly.Inaddition,wecoverthecritical selectioncriteriaforUVClight,particularly LEDs,andwhatparameterstoconsiderfor variousapplications.Alongsidethese,expect globalindustrynews,expertcommentary, andathought-provokingeditorialtoround outanissueyouwon’twanttomiss.

∗ Subjecttochangewithoutnotice.

Imprint

LEDprofessionalReview(LpR) ISSN1993-890X

PublishingCompany

LugerResearche.U.|©2001–2024 InstituteforInnovation&Technology Moosmahdstrasse30,A-6850Dornbirn,Austria,Europe info@lugerresearch.com|www.lugerresearch.com P+435572394489|F+43557239448990

Publisher

SiegfriedLuger

Editors

Subscribe

https://www.led-professional.com/misc/sub scribe

Advertise

https://www.led-professional.com/advertise

AnnualSubscriptions

LpRDigitalMagazine

• eMagazine(PDFdownload)

• 6IssuesperYear(Bi-monthly)

• FullArchiveAccess (allpreviouseMagazineissues)

• BusinessIssuetoshareandusewithin organizations

• EUR78.80

LpRPrinted&DigitalMagazine

• PrintMagazineincludingshipping

• eMagazine(PDFdownload)

• 6IssuesperYear(Bi-monthly)

• FullArchiveAccess (allpreviouseMagazineissues)

• Shippingcostsincluded

• EUR97.80

CoverPage: 6-starHospitalityApproachfor theShoppingMallNanjinginChina.Lighting DesignbyLichtvisionDesign. www.lichtvision.com Image:(c)LichtvisionDesign.

+4369911335570 s.luger@lugerresearch.com

Dr.GüntherSejkora +43557239448970 editors@led-professional.com

TheresaKönig +43557239448970 editors@led-professional.com

ElioA.Farina +43557239448970 editors@led-professional.com

Art&Design SarahLuger +436802305445 hallo@moments-of-aha.com

AccountManager

ChristineLuger +4369911335520 c.luger@lugerresearch.com

China,Hong-Kong LoloYoung +85297922081 lolo@castintl.com

Germany,International ArminWezel +493052689192 armin@eurokom-media.de

India

PriyankaRai +911244787331 priyanka.rai@binarysemantics.com

SouthKorea

Jung-WonSuh +8227858222 sinsegi@sinsegimedia.info

Taiwan

LeonChen +886225681786-10 Jeon@jkmedia.com.tw

Benelux,France,Ireland,Scandinavia,UK ZenaCoupé +441923852537 zena@expomedia.biz

USA&Canada

LesleyHarmoning +12186866438 lesley@lhmandco.com

JillThibert +12182802821 jill@lhmandco.com

Copyrights–LugerResearche.U.

Theeditorsmakeeveryreasonableefforttoverifytheinformation published,butLugerResearche.U.assumesnoresponsibilityforthe validityofanymanufacturers,nonprofitorganizationsorindividuals claimsorstatements.LugerResearche.U.doesnotassumeand herebydisclaimsanyliabilitytoanypersonforanylossordamage causedbyerrorsoromissionsinthematerialcontainedherein, regardlessofwhethersucherrorsresultfromnegligence,accident oranyothercausewhatsoever.Youmaynotcopy,reproduce, republish,download,post,broadcast,transmit,makeavailableto thepublic,orotherwiseuseLEDprofessionalReview(LpR)content withoutpriorwrittenconsentfromLugerResearche.U.

©2001–2024LugerResearche.U.–InstituteforInnovation&Technology–VATNo.ATU50928705,EORINo.ATEOS1000046213, CommercialRegisterFN316464p,RegionalCourtFeldkirch,Austria, Europe ■