In lower light levels, contrast becomes exaggerated, so a brightness balance needs to be more carefully crafted at a lower contrast for folks to feel comfortable. Humans see vertical surfaces before seeing horizontal surfaces, so vertical surfaces are important for a sense of safety and comfort.

Do the Basic Research

First, look at wattages that are interchangeable. Metal Halide lamps are not interchangeable. An LED module is not interchangeable.
MR 16 Incandescents have 10 wattages and eight different beam spreads. In LEDs there are only a few different beam spreads. Today most landscape lighting is done with MR 16s. With them, we have a whole toolbox we can interchange with the same fixture for all different kinds of effects.

This Lighting Comparison chart tested several light sources on a Black Walnut tree. We looked at the number of fixtures needed to create similar lighting effect as well as the wattage, beam spread, life, dimmability. Note that the MR16 Halogen and the LED are similar in life, but not cost. The LED light output is significantly less, but, clients are still concerned about cost. (Click on Picture to view larger Image)

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Making Your Choices

When you do a comparison of five different lamp types (Note that ?EUR??,,????'?????<

Replacement modules offer lighting designers the best option with LED equipment to date. But, as for having a workable toolbox right now, we are limited in available wattages and don?EUR??,,????'?????< (Click on Picture to view larger Image)

In landscape lighting, we have to deal with 13 different kinds of corrosion. A client should be very careful to have a good quality fixture. Cheap ones won?EUR??,,????'?????<

Compatibility Can Be an Issue

The MR 16 GU5.3 LED Lamp is not compatible with all electronic transformers due to its low power consumption of less than 8 watts. Symptoms of incompatibility include no light output, flickering, strobing, or random shutdown.

It also seems that 78 percent of the LED products tested failed to (for example) provide as much light or last as long as manufacturers advertising suggested. The LED manufacturers do not recommend using them in sealed fixtures. We have to be careful using LED replacement lamps on MR 16 fixtures. This has to do with heat. If heat is too high it negatively affects the output and light emitted. Lamp life also goes way down unless you know for sure that the fixture and LED lamp are compatible which means the manufacturer has done live tests. Otherwise you are taking a huge risk.

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I would like to have a way to tune the wattages and change the amount of candle power, but as of now most fixture manufacturers are saying that will come over next couple of years. We can?EUR??,,????'?????<

The LED modules usually have either multiple reflectors or lenses but they are typically shipped from the fixture manufacturer with one. If you want to be able to change the lens or reflector in the field, you have to specify all the options at the time they are being ordered. It would be great if the manufacturers offered a kit of all the lenses or reflectors for use in the field.

Because projects continue for years (whether done by us or not), the owner needs a record document and the plan/map. If they need replacement parts, they may also need controllers and lamps. The problem of course is that everything keeps changing. If you add trees, or need to move fixtures, you must continually update and reissue the record documents so they?EUR??,,????'?????<

The one issue that needs to be resolved is that LEDs are made in a sheet which is then cut up in pieces. Within that sheet the color differs from one place to another. Manufacturers do ?EUR??,,????'?????<

Effect on the Environment

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Black Walnut Comparison

Metal Halide 35 Watt PAR20 30???????(R)? Flood

• Number of Fixtures: 5
• Fixture Cost (Dist Net 2009): $348
• Lamp Cost (Dist Net 2009): $43.46
• Purchase Cost (Dist Net 2009): $1,957.40
• Total Wattage used: 225 (including ballast loss)
• Lamp Life at 120 Volts: 10,000 Hours
• Life at 10% dimming: NA

Incandescent MR16 with 2 20 Watt 38???????(R)? Flood & 6 35 Watt 60???????(R)? Flood

• Number of Fixtures: 8
• Fixture Cost (Dist Net 2009): $133.50
• Lamp Cost (Dist Net 2009): $2.50
• Purchase Cost (Dist Net 2009): $1,624
• Total Wattage used: 250
• Lamp Life at 12 Volts: 6,000 Hours
• Life at 10% dimming: 27,000 Hours
• Transformer Cost (Dist Net 2009): $536

Metal Halide 20 Watt MR16 with 2 25???????(R)? Flood & 6 40???????(R)? Flood

• Number of Fixtures: 8
• Fixture Cost (Dist Net 2009): $405
• Lamp Cost (Dist Net 2009): $40
• Purchase Cost (Dist Net 2009): $3,560
• Total Wattage used: 200 (including ballast loss)
• Lamp Life at 120 Volts: 12,000 Hours
• Life at 10% dimming: NA

LED ?EUR??,,????'?????<

• Number of Fixtures: 6
• Fixture Cost (Dist Net 2009): $577.50 & $212.50
• Replacement Module Cost (Dist Net 2009): $98 & $212.50
• Purchase Cost (Dist Net 2009): $ 2,489.00
• Total Wattage used: 89.6
• Lamp Life at 12 Volts: 25,000 Hours
• Life at 10% dimming: NA
• Transformer Cost (Dist Net 2009): $484.00

LED ?EUR??,,????'?????<

• LED ?EUR??,,????'?????<
• Fixture Cost (Dist Net 2009): $577
• Replacement Module Cost (Dist Net 2009): $98 each
• Purchase Cost (Dist Net 2009): $1,239
• Total Wattage used: 40
• Lamp Life at 12 Volts: 25,000 Hours
• Life at 10% dimming: NA
• Transformer Cost (Dist Net 2009): $84