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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | DIMMINGControlling consumers' expectations ofLED lighting: why dimming is so importantManufacturers of LED lighting products need to consider the control optionsfor their products and understand the applications in which their productswill be used, say CHRIS SALVESTRINI and AMANDA BEEBE.The US Census Bureau estimated thatthere are over 75 million owner-occupiedhomes (2007) and almost 5 millioncommercial buildings (2003) in the UnitedStates. Many of these buildings, both commercialand residential, already have dimmersinstalled. These existing dimmers are controllinga multitude of light sources, from incandescentto fluorescent and now LEDs, whichis why the capacity to dim must be designedinto an LED product from the beginning.Consumers, professionals, teachers and occupantsexpect to have control of their lights,and LEDs must meet this expectation if LEDlighting solutions are going to succeed.Why dim?The story of why to dim your lights has beenaround for a long time, and many peopleknow that lighting controls can improvepersonal comfort, increase occupant productivity,extend luminaire lifetime andsave energy. However, with the introductionof new lighting technologies it seemsthat this story is often forgotten, at leastuntil the market is full of disgruntled consumersand building occupants.The LED industry is heading toward thesame negative experiences as the screw-inCFL industry and needs to correct its coursenow, before consumers become averse toLEDs. LEDs are a promising new technologythat will eventually influence, and evenchange, the lighting industry. However, theywill not reach that point as quickly as theirpotential suggests unless the industry beginsto pay attention to consumer expectations.a)b)FIG. 1. a) Forward phase control and b)reverse phase control. Light blue showswhen the control is open (off) and darkblue shows when the control is closed (on).So what are those expectations?In the home, consumers expect their lightsource to act like the incandescent lamp thatthey have lived under for 100 years, meaningthat they want two things — color, and ambiancecreated with dimming. The screw-in CFLlamp continues to fall short of expectationsbecause it has failed to meet either of these criteria.Some LED makers understand the desirefor the perfect color temperature and are creativelyusing technology to provide the exactcolor of light that a consumer wants. However,these same manufacturers do not understandthat dimming is equally as important as color— consumers want just the right amount oflight for whatever they are doing.Commercially, the lights are on in a buildingto allow people to be productive. Toooften we think of energy-saving techniquesthat are only about turning the lights off.However, this tactic does not apply when abuilding or space is occupied, which makesthe ability to dim an equally importantenergy-saving technique.Dimming can be a manual choice by auser, a tuning decision by a building owner,or an automatic change due to the amountof sunlight. However, no matter which dimmingtechnique is used, it will save energy.While additional energy savings for anLED (which already save energy by replacinga 100-W incandescent with a 25-W LEDarray) may seem less important, consumersdo not agree. They are looking for every possibleway to save energy, and dimming willsave an additional 20%-30% on average withoutsacrificing comfort.In addition to energy savings, the occupantsof these buildings are the same peoplewho expect control in their homes, so whyshould they sacrifice this control at work?Dimming allows for increased productivity,which is paramount in a working environment.Everyone has different visual abilitiesand comfort levels, and being able to optimizeyour environment goes a long way.Now that you understand why dimming isimportant, you should also know that simplybeing “able to dim” is not good enough.Dimming is a quantifiable term and it shouldalways be associated with a dimming range,such as 100% to 1% of light output, as wellas other terms that describe that range (e.g.smooth and continuous). An LED array manufacturerwould never merely state that theirproduct “provides light” because that doesn’ttell the user anything, and the same goes forsaying a fixture is simply “dimmable.”AMANDA BEEBE is LED product manager and CHRIS SALVESTRINI is a senior design anddevelopment engineer with Lutron Electronics (www.lutron.com).LED control typesOnce you have accepted that high-qualityLEDsmagazine.com APRIL 2009 21Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS