LED technology allows you to create dramatic lighting effects by using a combination of light diffusion and color temperatures to control the warmth of the tone you desire for the landscape. LED also allows layers of color.
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LED is changing the landscape lighting industry. As with any new technology comes the need to explain some of the basic misconceptions about the product to ease this transition and guide consumers toward an improved option.
Some points to discuss in regards to LED lighting include color temperatures and their affect on the tones cast in the landscape, complexity of design and installation, fixture options and cost. LED (abbreviation for light emitting diode and also known as solid state lighting or SSL) offers many design options.
LED lighting comes in two forms, the Retrofit LED or an LED Specific Luminaire (fixture). The retrofit "bulb" style LED is made to replace existing conventional bulbs. In landscape lighting, the most common bulb currently used is the Halogen MR16.
An LED Specific Luminaire is a fixture designed and produced specifically for LED. According to the Department of Energy, the retrofit style bulbs are a good "stopgap" measure to transition the industry to LED luminaires, meaning they are a temporary option to replacing the existing fixtures.
Manufacturers design retrofit bulbs without the knowledge of the luminaire (fixture) housing that will receive the bulb, so difficulties can arise.
Retrofit bulbs have to contain a power transformer, driver, light engine and heat emission all packed into one compact space. This creates many points of potential failure, particularly the added heat of a luminaire that is not originally designed for LED.
Heat is the worst enemy of LED and greatly affects the life expectancy, quality of light produced and lumen output (amount of light emitted). These retrofit bulbs are typically rated at 20,000- to 25,000-hour life spans. However, many consumers find that they have to replace them once a year or even more often. This may be partly due to the luminaire not being designed for LED, and not allowing the heat to dissipate. This shortens the life of the retrofit bulb.
Quality may also be an issue with retrofit bulbs, as different levels of quality are now being produced. Consumers may find this isn't a cost-effective option due to the maintenance required.
LED-specific luminaires are fixtures with an LED light engine (panel containing the light emitting diodes) and a luminaire housing. High-quality LED luminaires are designed to emit heat properly to extend the life of the diodes and to maintain the maximum lumen output (brightness) to reach 50,000 hours or more in some cases.
This means that the LED will produce the full lumen output for 50,000 hours, and at the end of the life expectancy the efficacy (lumens/watt) of the LED will then begin to drop. With landscape lighting set to illuminate four hours a day, this equates to more than 34 years of life expectancy with a 50,000-hour rating.
Color & optics
The most common comment from consumers is the dislike of cool blue light while using LED lighting. This is an easily adjusted feature, with the option to order color temperatures as low as 2,700 K (K= Kelvin). With LED lighting, the color temperature rating affects the hue cast by the fixtures. The lower the temperature, the warmer the white light; the higher the temperature, the cooler the white light.
For example, 2,700 K produces a warm light, desirable for landscape lighting. LED can also be specified in 3,000 K to produce a neutral white light, or 4,000 K to produce a cool white light, which is a great option as a moonlighting effect on trees.
In comparison, most MR16 halogen bulbs are in the 3,000 to 3,500 K range, making the 2,700 K of the LED warmer than most consumers currently experience with their halogen bulbs.
The optics options with LED are vast. The lights allow specified beam spreads and lenses to diffuse as needed for the desired effect.
If a tall tree is being illuminated, perhaps the desired effect is achieved with a narrow beam spread with a clear lens. For small shrubs, a wide beam spread with fully diffused lens will create a mild, soft light restricted to the small circumference of the shrub.
Using the combination of light diffusion, and color temperatures to control the warmth of the tone cast, layers of color can create a dramatic landscape lighting effect. For example, path lighting or task lighting can be specified in a 3,000 K, while the perimeter shrubs and low-lying plants are specified in a warm 2,700 K, and the tall upper umbrella of trees can be set at 4,000 K, creating the moonlighting affect.
In addition to the white light options, there are also static color options of red, green, blue or amber, which are commonly used in commercial settings or themed lighting. The overall image can turn an average yard into a multilayered landscape masterpiece.
Quality made LED luminaires dissipate heat so efficiently that they can be handled and don't scorch foliage in the landscape. LED typically runs only 10 to 15 degrees above body temperature, compared to halogens that run 300-plus degrees above body temperature.
Also, LED does not produce infrared or UV rays; most landscape lighting is directed up from under the leaves, so the lack of additional UV or infrared light removes the concern of potential damage to plants and trees.
One further point in their environmental favor: manufacture of LEDs is minimal due to their long lifespan, thus reducing the carbon footprint. These qualities, combined with the low-energy use, make LED an environmentally friendly illumination that also has the added benefit of not affecting nightlife such as bats.
Installation & maintenance
With the lower wattage demand of the LED luminaires, a system can be installed with fewer and smaller power transformers, and four to five times more light fixtures per run, resulting in less wiring runs.
A common challenge in the installation of low-voltage systems is line voltage drop. This occurs when a wire run gets longer and loses voltage as fixtures are added the line. With a halogen system, this typically limits each wire run from the transformer to three to five fixtures, making the system require additional wire runs, additional labor to install them, and a higher amount of troubleshooting. Voltage drop in a halogen system also affects the light output down the length of the run. So if too many fixtures are added to a wire run or the length is too long, the first fixture may be at 100 percent of its potential lumen output, the next at 80 percent and the last fixture at 50 percent or less.
With an LED system, line voltage drop is hardly an issue. LED luminaires have a minimum required voltage to operate. Some may require as little as 9 volts and others may need 12 to 15 volts. As long as the minimum voltage is achieved for the LED luminaire, there is no change in lumens from the first luminaire on the run compared to the last. This is different than Halogen systems because the LED luminaire has a driver (an integral power supply) that maintains consistent current at the specific amperage required by the LED light engine, and is equally maintained at this amperage for each fixture.
For example, a run of LumaNIGHT Exterior LED Luminaires, model R3 (3 diodes, app 4.5 w) that need a minimum of 9 volts to operate, will run at the same high lumen output at the first fixture as the last fixture on the run as long as the line voltage does not drop below 9 volts.
Where the halogen system may have been restricted to three to five luminaires, you can now put 20 to 35 or more luminaires per wire run with an LED system. The number of luminaires is still determined by the gauge (size of wire) of wire and the length of the wire run.
LED luminaires have zero maintenance during their life expectancy aside from simple adjustments to the direction of light as the plant life grows and expands.
More precise control
Typically, LED landscape lighting systems have limited control. They're either on or off without dimming capabilities. With Lumastream, Inc. Intelligent Lighting Systems, there's another lighting option that offers landscape lighting (and interior lighting) that can be transformed with zoning, smooth dimming, scene control, dynamic color changing and static color options.
These systems are available in analog and DMX for various programming methods depending on the use/demand of the system. Scenes can be set to control your lighting based on your need for lighting throughout the night, or with DMX it can be as simple as a touch of a tablet computer or smartphone.
These intelligent control systems contain all electronics in one unit rather than having individual electronics at each luminaire, dramatically reducing additional points of potential failure inherent in other controllable systems.
Less expensive over time
The pushback on the upfront price of LED can easily be hurdled with the simple comparison to conventional systems. The cost savings from energy efficiency, ease and speed of installation, lower maintenance, quality of light, optics options, as well as the lifespan, far exceeds the approximate 25 to 30 percent price increase of an LED system.
The daily operating costs are very low; LED is 80 to 90 percent more efficient than other low-voltage systems, which are already 60 to 70 percent more efficient than high-voltage systems. Most LED landscape luminaires are designed with approximately 3 to 7 watts each, compared to the Halogen MR16 bulb at 35 to 50 watts each. Overall, you can get an excellent choice of design options, environmentally friendly landscape lighting system, low operating costs, and minimal maintenance by choosing an LED system.
April Buchan is regional sales manager at LumaStream, Issaquah, Wash., and has more than 12 years experience in residential and commercial construction. Contact her at firstname.lastname@example.org.