Many designers and property owners initially expressed concern over color rendering capabilities of LED lamps. Several years ago, chip manufacturers were trying to sell very blue lamps, well over 4,000???????(R)?k and as high as 15,000???????(R)?k. It was bordering on ridiculous. The chip manufacturers did not understand color preference, even though many people had all ready expressed their dislike of the bluish colors they were experiencing with compact fluorescent. Today, many LED sources, whether they are replacement lamps or integral modules, are available in some combination of 2,700???????(R)?k, 2,850???????(R)?k, 3,000???????(R)?k, +/or 4,000???????(R)?k, the color limit for landscape lighting.

Early into this transition, I questioned going into the warm end of the spectrum as far as 2,700???????(R)?k, but having seen many LED lamps in that range, the color is often preferable to halogen. The engineers have worked out a combination of phosphors and coating technique that produces an evenly warm color that complements landscape materials.

LED Replacment Lamps
In 2010, the range of light output and beam spread in replacement MR16 lamp LED units was limited. At that time there was not enough variety in light output and beam spread to provide landscape lighting designers enough flexibility to create solid, balanced compositions. For 2012, many manufacturers are offering LED MR16 replacement lamps in at least two outputs and up to four beam spread options, some using interchangeable lensing at the lamp. This does not offer designers as many options as we used to have, but the output of LED lamps is suggesting we may be okay with a little less option than we?EUR??,,????'?????<

The halogen units had been undervoltaged to extend lamp life, so even though the data showed higher output in the field, the LED lamps produced more light, and covered more area of the tree?EUR??,,????'?????<

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This Landscape Lighting Resource 2011 LED Lamp Comparison Notes chart for attendees of The Landscape Lighting Institute includes 40 replacement MR16 LED lamps tested to compare with the closest halogen lamp of similar beam spread. All normal lamp data was checked and listed. We started with a 20-watt halogen and included all LED units that did not substantially exceed that candlepower. The chart includes up to 35 watts of halogen and from 3 watt to 10 watts of LED. We then tried the lamps to see if they fit into a variety of outdoor fixtures, and whether they were rated for exterior conditions and use in an enclosed fixture. Dimmability was also checked. At the end of the testing we realized how much more complicated it is to specify LED lamps.

Does an LED MR16 replacement lamp operate in existing fixtures in the field?
Fixture manufacturers do not typically install and test LED MR16 replacement lamps in their fixtures to confirm acceptable p-n junction temperature. Some LED lamp manufacturers are suggesting that after approximately an hour of operation inside a sealed and gasketed landscape lighting fixture, the temperature will stabilize. If the lamp is still operating and not cycling on/off (if the lamp has a thermal cutoff), then it will be compatible with the fixture. Some LED replacement lamps, while not wider at the widest point than the 16/8 ths inch of a standard MR16 lamp, have wider configuration at the back of the lamp, making it incompatible with some fixtures installed in the field?EUR??,,????'?????<

Integral Module LED Fixtures
Two landscape lighting fixture manufacturers, BK Lighting and a new manufacturer (EcoLink), have developed a ?EUR??,,????'?????<

Three replacement LED MR16 lamps were tested against halogen MR 16 lamps. Two of the LED lamps tested (top and center) were 2700???????(R)?k. Compared with MR16 halogen lamps, their color was warmer, with less green tinge. The beam spread had intensity at the center and blended into the field with no striations, rings or any patterning.Note that the wattage and beam spread are not the same, which is one issue specifiers are grappling with in lighting today. Also, note that LED chip configurations vary. The middle 10-watt bulb uses only one LED chip, compared with four for the left one, and three for the right one. However, the single chip has stronger base material to operate at a higher current.

Are LED lamps or LED Fixtures Affordable Yet?
LED costs are coming down. We saw a big drop last year, and that is continuing this year. Many engineers working on LED products are suggesting we are getting nearer to prices becoming more acceptable as an alternative to what we have purchased all these years. Will prices ever get to under $10 per LED lamp? No promises there, but demand is picking up and the development technology just keeps charging forward. Most of the production is in China, but that appears to be shifting to a less centralized monopoly. And the new EcoLink unit with an integral led and tuning will cost less than many halogen fixtures.

About the Author
Janet Lennox Moyer is the founder of The Landscape Lighting Resource, a nonprofit in Troy, New York that encompasses all aspects of landscape lighting design and education www.tllr.org.