LumiGrow Delivers Energy- and Cost- Efficient Retrofit Solution to Address Global Ban on Incandescent Bulbs

San Francisco, CA – August 3, 2010 – LumiGrow, Inc., the leading provider of LED lighting solutions for agricultural and horticultural applications, today announced the release of the LumiGrow ECC™ series, a direct replacement for the incandescent bulbs used in environmental control chambers (ECCs) and greenhouses. The LumiGrow ECC-R™ and ECC-FR™ LED light bulbs provide plants with Red (660nm) and Far Red (740nm), respectively, and use 75 percent less energy than the incandescent bulbs they replace.

While other energy-efficient retrofit products, such as compact fluorescent bulbs, produce general illumination, they do not produce the Red and Far Red of incandescent bulbs. In independent laboratory studies conducted by both academic and industry researchers, the LumiGrow ECC-R bulb’s Red levels were shown to match those of 100-Watt bulbs, and the ECC-FR bulb’s Far Red levels slightly exceeded those of 100-Watt bulbs. Researchers can create custom color blends to achieve desired growth effects by simply varying the ratio of ECC-R bulbs to ECC-FR bulbs. The LumiGrow ECC’s dimming feature enables further fine-tuning of light levels.

Governments worldwide are restricting the use of wasteful incandescent lights. For example, the sale of 100-Watt bulbs is prohibited in the European Union. By September 2011, the EU will have banned the sale of nearly all incandescent bulbs. In the US, incandescent bulbs will be phased out beginning with 100-Watt bulbs in 2012 and ending with 40-Watt bulbs in 2014. Australia has already placed an outright ban on the sale of the bulbs. The LumiGrow ECC bulbs simply screw into standard sockets, making them a straightforward retrofit that ensures compliance with new legislation.

The LumiGrow ECC series bulbs operate at just 17 Watts, producing annual savings of over 500 kilowatt-hours compared to 100-Watt bulbs. In addition, they avoid the electrical cooling requirements inherent to incandescent lights because they do not emit infrared light. An estimated 80 percent of the energy burden of environmental chambers results from removing the unwanted infrared energy generated by incandescent bulbs. For example, replacing 45 100-Watt incandescent bulbs in an average (8×8) style chamber with LumiGrow ECC bulbs would reduce the heat load of an environmental growth chamber by 176,000 BTU’s (18 tons) per day. That’s enough to cool an additional 1000 sq feet of office space all day.

LumiGrow ECC bulbs last 10 to 20 times longer than standard bulbs, minimizing capital outlay and ongoing operating costs. Users can expect to recoup their investment in less than two years by significantly reducing power usage, cooling requirements and maintenance costs.

“The academic community has clamored for an LED solution to reduce the high costs and energy demands associated with operating growth chambers and greenhouses,” said Kevin Wells, founder and CEO, LumiGrow. He added, “We’re pleased to answer the call with the LumiGrow ECC series.”

About LumiGrow, Inc.
LumiGrow, Inc. is the leading provider of LED lighting solutions for agricultural and horticultural applications. Proven in third-party studies to boost crop yield and reduce operational costs, LumiGrow LED lighting systems are the tested-and-proven choice of researchers and commercial growers including Dow AgriSciences, Duke University, US Department of Agriculture and University of California at Davis. Headquartered on Treasure Island in the San Francisco Bay, LumiGrow is privately owned and operated. For more information, call (800) 514-0487 or visit http://LumiGrow.com

LumiGrow, LumiGrow ECC, LumiGrow ECC-R and LumiGrow ECC-FR are trademarks of LumiGrow, Inc.

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Why should I use the LumiGrow ES LED light instead of an HID lamp?

Given their advantages, it’s no wonder LEDs are making a big impact on the horticultural lighting world. But what exactly is an LED?

LED Basic Facts

A light emitting diode is a crystal that emits light when electric current passes through it. This property was first discovered in 1907, but it took until 1962 for LEDs to become commercially available. The LED’s color depends on the elements used to make the crystal. For example, red LEDs contain aluminum, indium, gallium and phosphorus.

The earliest LEDs were red, followed by amber, yellow and green. Blue LEDs eluded researchers until 1992, and full color (RGB) LED displays followed soon after. White LEDs are simply blue LEDs with a yellow phosphor printed on the crystal surface — the blue light makes the phosphor glow yellow and the two colors mix to produce a bluish-white.

An LED’s light output depends on its “quantum efficiency,” or the crystal’s ability to convert electrons (electricity) into photons (light). An LED will produce more light as more current passes through it, until self-heating at very high currents reduces its quantum efficiency. As the LED heats up, it produces less light with more current. This is why it’s very important to keep LEDs cool; cooler LEDs produce more light. Because they don’t radiate any heat, the way to cool LEDs is by mounting them to a heat sink, like a computer CPU.

LEDs Cross Brightness Barrier

The LED most people are familiar with comes in a bullet-shaped 5- mm package, with a clear epoxy body holding two long leads that support the LED crystal, or “die.” The 5-mm LED package is cheap to produce but not good at removing heat from the die, so the 5-mm LED is limited by self-heating to drive power levels below 20 milliwatts (0.02 watts). They’re good for panel indicators and flashlights, but they don’t produce enough light for general illumination.

LED technology advanced to enable 1-watt LEDs by the late 1990s, and finally crossed the lighting-class brightness barrier in 2001 with Philips Lumileds’ introduction of the Luxeon family of 3-watt LEDs. These were followed by the LuxeonIII family of 5-watt LEDs in 2003. Cree and Osram Opto followed suit with their X-Lamp and Dragon series LEDs in the 3- to 5-watt range. Manufacturers continue to develop new LED materials that improve quantum efficiency and new package designs that remove more heat from the LED die.

The light output from multi-watt LEDs is great enough to match conventional lighting technologies in specific scenarios. High-power LEDs now find use in architectural lighting, flashlights and daytime running lights for cars. Because each LED has a narrow beam like a small spotlight, illuminating a large area requires an array of many LEDs—currently an expensive proposition for general lighting applications, but a justified expense where energy savings, maintenance cost reduction and crop yield take precedence. The savings in electrical power and cooling costs make LED lighting a worthwhile investment for eco-conscious greenhouse and indoor growers.

Photosynthesis Basics

To understand why LEDs are so well-suited to growing plants, let’s review a bit of plant biology. Then we can compare LED lighting solutions to HID lamps to determine which is better for plants.

Plants perform photosynthesis using two types of chlorophyll: Chlorophyll-A, with peak response at 430nm and 680nm, and Chlorophyll-B, with peak response at 450nm and 660nm.

While blue light in the mid-400nm range can activate photosynthesis, plants mostly use red light in the 650 to 700 nm range. But pure red light produces abnormal plants, indicating that blue light is required for proper growth. Blue light also tells the leaves to open their stomata and allow CO2 in.

Notice that green light produces no response in the chlorophyll curves. Plants look green because their leaves reflect the green light. Human vision, however, is most sensitive to green light—an advantageous adaptation for a species that evolved in the forest.

Measurements of an air-cooled HPS lamp show that more than 60 percent of the electrical energy is turned into heat and ultraviolet light, and only 32 percent of the electrical energy used is turned into light energy (MacLennan, 1994). HID lamps produce light that’s useful for humans, meaning that most of their light energy output is in the green part of the spectrum, with less than 10 percent of that output in the red and blue regions where plants use light.

Therefore, we see that the typical HID output spectrum is actually the opposite of what plants really need. HID grow lights work only because they are using so much energy that their 10 percent output in the photosynthesis region is enough to grow plants.

Target the Spectrum Plants Need

LEDs allow us to take a targeted approach to horticultural lighting by converting electricity into only the light energy that plants will use. Instead of wasting energy producing the broad emission spectrum of an HID lamp, the LEDs create very narrow emission spectra: 20nm to 40nm spread compared to several hundred nm for an HID lamp.

Meanwhile, LEDs are very efficient at creating light from electricity. At least 20 percent of the electrical energy put into an LED turns into light, and all this light is usable for photosynthesis. For the HPS noted above, only 10 percent of the 32 percent conversion efficiency is in the photosynthesis region, meaning that the HPS is only 3 percent efficient at creating light usable by plants.

The savvy grower should look for the following features in a high-quality LED lighting solution:

High-Power LEDs

The small “bullet” or 5mm LED does not have enough power for horticultural applications. This type of LED is limited to less than 0.02 watts of power. This means that it would take 250 5-mm LEDs to equal the light created by one 5-watt power LED. Clearly, the 5-mm LED is inadequate for growing plants.

Growers should only consider lights made with high-power LEDs. “High-power” LEDs have power ratings greater than 1 watt. LEDs in the 3-watt class include the Cree XR-Lamp, Luxeon Rebel, and Luxeon K2. Some 5-watt LEDs include the LuxeonIII and the Osram Platinum Dragon series. High-power LEDs are identifiable by a large metal pad on the bottom of the LED package. This metal pad provides a direct path for heat to escape the LED, usually by means of a connection to a heat sink.

Reputable LEDs with Accurate Lifetime Ratings

When comparing lighting solutions, it is important to understand how manufacturers specify lifetime hours for different lamp types. HID bulb lifetime is specified as time-to-failure, usually something less than 20,000 hours. Light output from HID lamps degrades long before the bulb burns out, noticeably decreasing as soon as 5,000 hours. Growers using HPS lamps, for example, will routinely change bulbs every 6 months to maintain light levels in their grow rooms.

By comparison, an LED’s lifetime is specified as the time for its light output to degrade to 70 percent of its initial output. Manufacturers specify 70 percent lifetimes between 50,000 and 100,000 hours. However, to achieve the LED’s predicted lifetime rating, the light must operate the LEDs within the manufacturer’s temperature limits. Operating LEDs at high temperatures reduces their lifetime.

In order to trust a light’s LED lifetime rating, find out which LEDs the light uses. Reputable makers extensively test their LEDs and employ strict process control in order to provide a real guarantee of operating lifetime. Poor-quality LEDs exhibit lifetime problems caused by skimping on process control and testing to lower quality standards.

High-Power Cooling System

Like the CPU in your PC, high-power LEDs must be cooled with a heat sink and fan. Because high-power LEDs do not radiate any heat, the metal pad provides the only path for heat to leave the LED. Heat flows from the LED die, through the metal slug, through the circuit board, into a heat sink and then out to the surrounding air.

Look for LEDs mounted on a metal-core printed circuit board (MCPCB), a space-grade technology used for operating electronics at high temperature. An MCPCB conducts hundreds of times more heat compared to the typical fiberglass circuit board. An MCPCB is required for the high power levels that LED horticultural lights endure.

Finally, make sure the MCPCB is mounted to a large heat sink, preferably one with many fins. More fins provide more surface area to dissipate heat into the surrounding air. The heat sink should be cooled by multiple fans to prevent a single-fan failure from damaging the LEDs. The light’s datasheet should list the fan’s predicted lifetime.

Constant-Current Driver Circuit

The electronic circuit powering the LEDs is an important consideration when evaluating LED lights. The LED “driver” circuit is like an HID ballast; it converts AC input power into DC power at the proper voltage and current level for the LEDs. Its most important job is supplying a constant DC current even as the LED voltage changes over time and temperature.

Many simple driver circuits provide a constant voltage, meaning the output current varies with the LED voltage. A constant-voltage driver can cause early LED failure. As the LED’s temperature increases, its voltage drops, causing a constant-voltage driver to supply more current in response to the decreased LED voltage. This feedback loop results in a runaway current that destroys the LED.

Proper LED driver circuits supply a constant DC current, holding steady as the LED voltage changes with temperature. Look for the words “constant-current” in the horticultural light’s LED driver specifications.

Adjustable Output Spectrum

Because LEDs are inherently dimmable, an LED solution should let the grower tailor the light output spectrum. Look for an LED light that provides individual brightness controls for each color of LEDs. By varying the output power of individual colors, the grower can simulate seasonal light changes over a multi-week growing cycle.

For example, more blue light mimics the summer sun (vegetative phase), and more red light simulates the sunlight in the fall (flowering phase). This type of spectrum change is similar to the effect achieved by starting plants under MH lamps for vegetation and then changing to HPS for flowering. Growers can even tailor the light spectrum to suit individual plant type.

Rigorous Testing by Recognized Experts

The LED lighting marketplace can be confusing. How does one separate fact from fiction when reading manufacturer claims about electrical savings and plant growth? Look to see with whom the manufacturer has partnered to conduct product efficacy testing. The LumiGrow light, for example, has performed successfully in extensive testing by independent researchers at the University of California, Davis and Duke University among others. Whether greenhouse growing is your livelihood or your hobby, don’t risk the health of your crops or your budget on inadequately tested LED lights.

The problem with lumens is especially pronounced when measuring light at the far ends of the human visual response curve. Consider three lamps—red, green and blue—each emitting the same number of watts of optical energy. The red and blue lamps would have much lower lumen ratings compared to the green lamp, simply because the human visual response is very low at red and blue, and highest at green. That’s why a high lumen rating does not necessarily make a lamp better suited to growing plants.

Similarly, light meters that measure in “lux” tell us very little about a lamp’s plant-growing power. The light sensors in lux meters have their own spectral response curves which may over- or under-measure light at various colors. This is why lux meters usually have different settings for “sunlight,” “fluorescent” and “incandescent” lamps. Again, because lux meters are meant for measuring the amount of light usable by humans, they don’t tell us anything about how plants will respond.

Plant biologists define light in the 400nm to 700nm spectral region as “photosynthetically available radiation,” or PAR. The unit for measuring PAR, micro-mols per second (μmol/s), indicates how many photons in this spectral range fall on the plant each second. Inexpensive PAR meters use sensors that respond over the entire 400-700nm spectrum, and have their own sensitivity curves that require different calibration for sunlight, fluorescent and HID lighting.

All these systems are too broadly responsive to measure an LED’s narrow emission spectrum. They make HID light seem brighter by over-measuring yellow-green light, and make LED light seem dimmer by under-measuring red and blue light.
To properly measure the amount of energy present for photosynthesis we must use a spectroradiometer. This instrument measures energy in watts at each specific wavelength over a range of wavelengths. A spectroradiometer can provide a direct comparison of each lamp’s ability to produce light that plants can use for photosynthesis. Spectroradiometers are expensive instruments, not usually found outside laboratories. (A more common instrument called a spectrometer can show relative light output over a spectral range, but does not measure energy in watts.)

Manufacturers should publish spectroradiometric data showing the energy per wavelength produced by their lamps. This data will allow growers to accurately compare different lighting technologies—whether HPS vs. LED or different LED horticultural lights—and know how much usable light their plants will receive from each system.

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