By JIM BENYA
The downlight as we know it was invented in 1939 by Rambusch Lighting. Famous for ecclesiastical lighting of churches and cathedrals, Rambusch knew that illumination of hymnals and prayer books was typically poor because chandeliers were hanging far overhead of the congregation. A recessed luminaire with a narrow beam effectively lighted the “tasks” an invention that changed church lighting forever. But modernism and its demand for un-ornamental design gave us the “can light” (aka the “pot light” in Canada) that probably lights more interior space than any other lighting fixture type to date.
Residential downlights played a huge role in the acceptance and growth of the industry. Offering different apertures of varying diameter and shape, as well as interchangeable trims ranging from open baffles to shower lenses and wall washers, allowed for the customization of lighting for each room and function. As the market grew there were dozens of companies and an increasing number of options, including low voltage and compact fluorescent light sources.
Unfortunately, fires resulting from overheated downlights became a problem, and the National Electrical Code responded with a series of strict UL listing requirements. Thermal protection, insulation detectors and insulation contact (IC) housings became standard. As downlights became popular for hotels and apartment buildings, the need for fire-rated downlights entered the codes and marketplace. Selecting a residential downlight housing quickly became complex and further complicated by compact fluorescent lamps and the huge variety of variations. Once popular because of low cost, residential downlights were rapidly becoming expensive.
Adjustable Downlight with Pinhole Trim and Fire Rated Junction Box (dmf Lighting).
Well, everything changed when a 7.5watt LED luminaire could generate as much light as a 60-watt incandescent luminaire. Manufacturers and lighting designers began to question everything about downlights to regain their popularity and cost effectiveness. Thanks to LEDs, downlights have become affordable, and the new section in the 2020 National Electrical Code resolved the complications that accumulated over 50 years of legacy light bulbs. Four of the more noteworthy innovations and adaptations include:
• Low wattage downlights that clip into the ceiling – With common cans, the electrician nails the can light’s hanger bars in place, wires the 120volt branch circuit to the junction box, and returns after drywall work to find the can and cut out the hole before installing the guts and trim. Moving a downlight means a lot of drywall work as well as electrical work. With clip-in fixtures, the wiring is put in before the drywall, then the electrician cuts a hole, grabs the wire, connects it to the luminaire, and pushes the luminaire into the hole. Spring loaded “mousetrap” clips hold the luminaire in place. Moving a luminaire is easy and involves a minimum of drywall and electrical work. Significant labor cost savings are the key.
• Low voltage downlights – LEDs are inherently low voltage light sources. Encouraged by UL 2018 and Articles 411 and 725 of the National Electrical Code, a new generation of downlights allows for a Class 2 driver connection to 120-volt power on a flexible whip, that in turn can power up to 60 watts of downlights using plug-in class 2 flexible wiring. This could include dedicated above ceiling drivers or PoE-wired applications. These take advantage of clip in downlights to make the labor savings even more impressive.
• Fire-rated downlights – Especially in multi-family structures where ceilings are required to be fire rated, contractors were required to either build a sealed drywall box around a recessed downlight or to cover it with a UL listed fire protection blanket until recently. The added costs for either can be as much as $150 per downlight in labor and material. More than half of these costs are saved by new generation of downlights, including compact LED sources that fit into fire-rated junction boxes and firerated versions of conventional can lights. With up to 10 downlights in a mid-market 2-bedroom apartment, these savings become important and preserve the appeal of downlighting in these project types. These lights can be used in hotel guest rooms that for the same reason.
• Multiples are better than ever – The smaller size of LED options have resulted in a completely new generation of luminaires that feature multiple sources connected to one power source. These include conventional “multiples” with several individually aimable heads and new types of wallwashers and small linear downlights on a residential scale. Like the other innovations, these often use mousetrap clips for simple cut-in installation and low voltage class 2 wiring, making these appealing for a wide range of projects and budgets.
Perhaps most intriguing of these innovations is their small size. For instance, a 2-3/8” x 1-5/8” square downlight with two micro downlights can produce up to 400 lumens using 5 watts, and with several of them connected to a single class 2 driver, can be installed for the labor cost of a single conventional 6” can. Not only more sophisticated in appearance and performance, but it is also a whole new design look that are affordable in a larger percentage of projects.
I’m still learning how to use these innovations, and every day I receive an email announcement of a new product of this type from companies all over the world. In downlighting, this is our future because it is a better tool for smaller environments, energy efficient, resource efficient, and a dramatic improvement in the downlight on which so much lighting design depends.
Mousetrap clip-in downlight (Lightheaded)
Fire rated conventional downlight (Juno)
Class 2 wiring for 4 luminaires from one driver (series constant current) (Alphabet)
1-3/4” wide customized multiples with recessed and monopoints (Alphabet)
While LED lighting has taken off in homes and businesses in the past few years, you most likely have been taking advantage of this lighting technology for decades in everything from televisions to watches to traffic lights to exit signs.
Older lighting technology such as halogen, incandescent and fluorescent lights continue to give way to light-emitting diodes or LEDs, which are brighter, last longer, and are more energy efficient.
“2021 saw progress both in terms of LED deployment and lighting efficiency gains,” reports the International Energy Agency (IEA). “Over 50 percent of buildings sector lighting markets globally are covered by LEDs. While numerous countries began to phase out incandescent lamps more than ten years ago, many are now beginning to eliminate fluorescent lighting to make LEDs the main technology.”
LED Lights: Rapid Deployment Since 2010
The IEA global lighting sales historical infographic shows the meteoric rise of LED lighting market share in the last decade:
- 2013: LED 3 percent
- 2014: LED 7 percent
- 2015: LED 14 percent
- 2016: LED 18 percent
- 2017: LED 24 percent
- 2018: LED 29 percent
- 2019: LED 39 percent
- 2020: LED 51 percent
During that same time frame, incandescent lighting went from the market leader at 53 percent in 2010 to just 4 percent in 2020. Compact fluorescent (28 percent), halogen (11 percent), and linear fluorescent (5 percent).
The IEA goal is 100 percent LED within three years.
“LEDs are shaping current market dynamics. The momentum created by the ongoing phase out of incandescent and halogen lamps as well as declining shares of fluorescent technologies is raising lighting efficiency globally,” says the IEA.
LED Lights: 75 Percent Less Energy, Can Last 25x Longer
The U.S. Department of Energy (DOE) says that residential LEDs use at least 75 percent energy, and last up to 25 times longer than incandescent lighting.
“LED is a highly energy-efficient lighting technology and has the potential to fundamentally change the future of lighting in the United States,” says the DOE.
The DOE describes the differences between LEDs and other types of lighting as:
- Light Source: LEDs are the size of a fleck of pepper and can emit light in a range of colors. A mix of red, green, and blue LEDs is sometimes used to make white light.
- Direction: LEDs emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light. This feature makes LEDs more efficient for many uses such as recessed downlights and task lighting. With other types of lighting, the light must be reflected to the desired direction, and more than half of the light may never leave the fixture.
- Heat: LEDs emit very little heat. In comparison, incandescent bulbs release 90 percent of their energy as heat and CFLs release about 80 percent of their energy as heat.
- Lifetime: LED lighting products typically last much longer than other lighting types. A good quality LED bulb can last 3 to 5 times longer than a CFL and 30 times longer than an incandescent bulb.
Understand the “D” in LED: Diodes
LEDs, according to the Lighting Design Lab, are fundamentally different from conventional light sources such as incandescent, fluorescent, and gas-discharge lamps, in that LEDs use no gas or filament; have no glass bulb; and have no failure-prone moving parts.
As the name suggests, the key to understanding LED lighting is the diode.
“A diode is the simplest sort of semiconductor device,” says How Stuff Works. “Broadly speaking, a semiconductor is a material with a varying ability to conduct electrical current.”
The diode in LEDs restricts the direction of movement of charge carriers, essentially allowing electric current to flow in one direction.
Other advantages of LEDs include:
- Mercury free
- No infrared radiation
- Can operate in cold environments
- Can withstand vibrations and impact
- “Instant on”: reaches full brightness as soon as they are turned on
Historical Timeline of LED Lights
LED Lights may feel like 21st century invention, but the concept has been around for more than 100 years.
Here’s a timeline of the History of LED Lighting:
- 1907: British engineer and early radio pioneer, Captain Henry Joseph Round, publishes in Electrical World his discovery of the phenomena of electroluminescence in which a material emits light in response to a passage of an electrical current.
- 1924-1941: Russian scientist and inventor, Oleg Vladimirovich Losev, published a series of articles on the theory of how LED lighting could work and possible applications.
- 1955: American physicist, Rubin Braunstein, publishes the first measurements of infrared emissions by diodes made from crystals of gallium arsenide (GaAs), gallium antimonide (GaSb) and indium phosphate (InP).
- 1961: Robert Biard and Gary Pittman team up at Texas Instruments to produce and patent the first infrared LED.
- 1962: Nick Holonyak invented the first LED to emit visible red light while working at a General Electric research lab.
- 1964: IBM introduces red LEDs to their computer circuit boards.
- 1968: Hewlett Packard integrates LEDs into their handheld calculators.
- 1972: Monsanto electrical engineer, M. George Craford, invents the first yellow LED (using one red and one green chip) as well as red and orange LEDs 10 times brighter than Holonyak’s earlier versions.
- 1976: Thomas P. Pearsall developed the first high-brightness and high-efficiency LEDs for optical fiber telecommunications.
- 1993: Shuki Nakamura makes the first high brightness blue LED using Gallium Nitride (InGaN).
“The advent of blue LEDs enabled the creation of what we now see commonly throughout the world: white LEDs, of which there are two types. The first mixes blue LEDs with a yellow fluorescent substance to create a white emission, while the second combines blue, red, and green. Either way, LEDs that emit a white light would not exist today without the hard-earned creation of the blue,” says Embedded Computing Design.
- 2002 white LEDs are commercially available but at a high price tag (between $80 and $100 per bulb)
- 2006: LEDs with 100 lumens per watt are produced for the first time.
- 2007:
PWM becomes the first manufacturer
to develop standard surface-mounted device (SMD) LED digits for fuel station price signs.
- 2010: LEDS with 250 lumens per watt are produced.
- 2011:
Phillips wins the L Prize
for energy efficient lighting from the Department of Energy (and $10 million cash award) for producing a LED bulb that generates as much light as a 60-watt incandescent at 900 lumens but consumes less than 10 watts with a life rated at over 25,000 hours.
- 2014: The Nobel Prize in Physics is awarded to Nakamura, Isamu Akasaki, and Hiroshi Amano for their work on blue LEDs, which helped lead to today’s advances.
- 2015:
PWM launches the first full-color price sign digits
with a combination of red-green-blue (RGB) within an individual LED allowing for millions of colors to be mixed.
Since then, LED lighting technology is continuing to improve as it lights up the world.