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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSshow report | STRATEGIES IN LIGHTCourtesy of Strategies UnlimitedSignals1%Lighting9%Automotive15%2008 HB-LED marketTotal market: $5.1 billionOther15%Signs/ displays17%Mobileappliances43%FIG. 2. Mobile appliances remained the largest HB-LEDapplication in 2008, although Lighting showed the mostrapid growth.Woodbury, director of energy services withRepublic ITS, provided the perspective of aformer public works director turned consultantwho has completed conversions ofover 45,000 street lights. He warned of thebad taste that can be left in the mouth ofa municipality that invests in LED streetlights and gets stuck with disappointingperformance.“In terms of reliability, we have to get thebad product out of there, and get reputablecompanies in there with good products,”Woodbury said. He talked about theimportance of avoiding “LED hype”when promising energy savings,maintenance savings and evenlife cycle costs, which for variouspractical reasons can turnout to be disappointing oncelighting is installed.All of that said, LED streetlights can be quite successful andare becoming more so with time.Currently, LEDs are bright enough forstreet light applications, but are still on theexpensive side both initially and in terms ofactual energy savings, he said. In addition,LED performance data needs standardization,and lighting industry guidelines needto be developed to account for factors suchas light measurement under mesopic conditions.However, Woodbury expects thecurrent rapid pace of technology change toaddress such issues significantly in the nextcouple of years, saying, “LEDs are gettingthere.”Replacement lightingA key factor for LEDs inreplacing conventionallight bulbs is the ongoingtransition from LED bulbs(standard LED componentsarranged to mimic conventionalbulb shapes) to SSLsources (lighting fixturesdesigned specifically forLEDs), according to MarkMcClear, business developmentdirector with Cree. “Abulb is an adaptor, a bridgeto the real LED fixtures,” hesaid. “But we’re stuck with itfor now.” LED bulbs potentiallyprovide longer life andmuch better efficacy than their conventionalcounterparts, but thermal limitations inherentto the form factor will eventually drive atransition to SSL sources.For instance, in attempting to simulatean MR16 using an LED bulb, McClear andcolleagues at Cree realized that since theycould only drive the LED device at 5 or 6 W,the performance was only equivalent to a20 W MR16 at an industry-standard 3000Ka)color temperature. “35W might be availablelater,” he said. “But 50W does not look possibleusing standardcomponents.” Theyfound similar limitationsin attempts tosimulate both A19 andPAR 38 bulb designs.Not everyone agreed withMcClear’s conclusions about thermodynamiclimits to LED bulb brightness.Densen Cao, president of CAOGroup, described 3-D LED-basedlight sources for direct replacementof traditional incandescent lamps instandard sockets, such as candelabra,S14, 1156 and others (Fig. 3). The 3-DLED and driver element essentiallytakes the place of the filament in astandard bulb structure. Ten and 25W replacements are currently availableand the company expects to havedirect replacements for the majorityof bulbs (40 and 60 W) within the nexttwo years. “The key is not the LED butheat management,” said Cao.Commercial and industrial lightingCurrently, LED bulbs can use inherentdirectionality to improve their performancewith respect to conventional lightingsources, said McClear. LED bulbs arehighly suited for refrigerated high-bayapplications because they have alreadyachieved energy parity with the most efficientalternative — T8 fluorescents — butdo not suffer from cold temperature sensitivity,as fluorescents do. Initial costb)FIG. 3. CAO Group’s a)Dynasty S14 and b) 1156LED bulbs are designedas direct replacementsfor incandescents, andcontain a replaceable LEDsource with a 360-degreebeam pattern.18 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS