50 Shades of LED

Warm white 2,700K light brings life to the warm siding, but the plantings are not as vibrant.

All photos provided by Kichler Lighting

Pure white 3,000K light renders this siding sterile, while the full color of the foliage is raised in brilliance.
The lifeless pallor of this redwood-sided wall is caused by the use of 4,250K cool white light, a poor choice for residential property, though it has applications for commercial property.

By Jeffrey R. Dross

Now more than ever, a basic understanding of color temperature as an indicator of hue is critical to creating beautiful landscape lighting designs.

Hue is the complexion, shade or tint of a color. Few colors are true. Red, for example, may be reddish-orange or reddish-blue, and white light may have a cool blue or warm-golden cast. Incandescent, Halogen and Xenon lighting are available in only one color without the use of lenses or other tinting devices. Energy-efficient LEDs, which are growing in popularity in landscape use, now are available in many colors that can contribute to strikingly attractive designs.

With new lighting technologies available, understanding color temperature to ensure use of compatible shades of color throughout a landscape lighting design is quickly becoming a must.

Mastering color temperature and Color Rendering Index

To master the use of color, let’s start with vocabulary and some benchmarks. The color of light is measured by its color “temperature,” stated in Kelvin (K) units. Pure white light has a color temperature of approximately 3,000K. A standard, 60-watt incandescent light bulb has a color temperature of approximately 2,700K, emitting a white light that has a very warm yellow or golden cast. Daylight is actually very blue in color, with a color temperature range of 5,500K to 6,000K.

Color Rendering Index (CRI) is the measurement of light’s ability to interpret color. A CRI of zero is a gray-scale, much like a black-and-white movie or photograph. The closer to a maximum 100 CRI, the more vibrant the color appears. To fully realize color, a high CRI should be specified alongside color temperature.

When the first LEDs appeared on the market, they emitted a blue-white light with a low CRI that, in landscape design, often caused the surrounding objects to appear cold and grayish in color. Today, LED lighting is much more advanced and is available in colors and color renderings that are much more pleasing to the eye.

Have you noticed something? Daylight, which is bluish-white light, a color we call cool, has a higher color temperature (5,500K – 6,000K) than yellow-white light (2,700K), a color we call warm. Once you are aware that the language of color temperature works the opposite of the language of weather temperature, understanding color science becomes much easier.

In the garden

Experiments have shown that bold colors, especially purple but also including deep red and blue-green, look best when lit with pure white light (3,000K), while earth tones look best when lit with warm colors with lower color temperatures (about 2,700K.)

Let’s start with flower beds. Typically, beds are a combination of bolder-toned flowers and green foliage. We know that reds become more dynamic, purples more vibrant, and greens more stunning when illuminated with 3,000K pure white light. If the beds, however, are filled with yellow and orange flowers, 2,700K light could be considered.

Birch trees, with their stunning white trunks, can look grayish and drab in a bed lighted with 3,000K pure white light, making the warmer 2,700K lighting a better choice. Evergreen trees, especially those with a punch of blue, such as spruces, are best served with 3,000K lighting. Traditionally, spruces have been lighted with incandescent lamps featuring blue lenses. Adding a blue lens to a 3,000K light further intensifies the dense blue-green coloration.

Around the home

Traditionally designed homes typically feature warm wood tones, stonework, and brickwork with its red, orange or gold undertones. These homes look best under 2,700K lighting because 3,000K light can create a cold or sterile appearance. With contemporary architecture, cool-colored building materials such as glass, concrete, extruded aluminum and slate “pop” in a manner pleasing to the eye under a 3,000K light source.

Outdoor artwork may be a prominent feature in your design, and care should be taken to light it properly. Consider the material and its color. Rusted metal, a common media in garden art, will respond best to the warmer white light offered by 2,700K light sources.

Another consideration: Lighting used in gardens often overlaps with that used to light the architecture of the home and its architectural features and enhancements. What should a good lighting designer do with dissimilar color palettes? Start by asking yourself, “What is the purpose of the light?” “Will the results conflict?” And, “What is most important to the total landscape design?” Your answers will help you make a better decision. If the entire building is lit with 2,700K lighting, and you have a small section on one end of the property that calls for 3,000K, unify the look with 2,700K everywhere. If the most important part of your design is a well-lit spruce, use the 3,000K light everywhere and don’t worry about the overspill.

You may notice this discussion has been restricted to 2,700K and 3,000K light options, because these are the most popular lighting options now available. In some instances, a lower color temperature might be preferred, but insufficient lumen output may be an issue. Higher color temperatures, most commonly 3,500K, are also commercially available, but are not recommended for residential landscape lighting use. In commercial property, 4,250K light is often used where building materials are receptive to its sharp blue overtones.

Color and design quality

Once upon a time, landscape lighting options were limited to one fixture with one beam spread. Today, options include a full cadre of fixtures, beam spreads, lumen outputs and various colors of light. The result is that all can be used to maximize the aesthetic results and create exciting and engaging nighttime exterior environments. As the landscape design profession evolves to better satisfy today’s more sophisticated homeowners and compete for tomorrow’s, those designers who are color-smart and lighting-savvy will have a clear advantage.

Jeffrey R. Dross is corporate director, education and industry trends at Kichler Lighting. For more information, visit www.kichler.com.