Thursday, 23 June 2011
A Guide to Exterior Lighting
A Guide to Exterior Lighting
Safety, security and aesthetics all play an important part in illuminating the outside of your house
by Martha Tuzson Stockton
Evenly spaced driveway lights show the path to the door.
Fixtures that cast small pools of light are more than adequate to lead a car up a winding driveway to the house.
Life hasn't been the same since Edison in-vented the light bulb. This handy source of light allows us to work, play and sleep without regard for the daily cycles of the sun. After the sun goes down, we can shine a light when things go bump in the night. With the proper illumination, we can change the exterior of our homes, too. Lighting allows you the rare opportunity to control the views of your house and your garden, to highlight your favorite elements and to create a setting different from the one seen during the daytime.
A few well-placed lights can make patios, gardens and porches more lively, and can show guests a safe, inviting path to your front door. The most successful lighting plans discover critical locations for lighting and combine them with appropriate fixtures, creating patches of slightly brighter light in key locations while providing enough light between them to avoid intense contrast.
Use less light for better visibility when lighting for safety—Quantities of light given off by a light source are called lumens. The light output of lighting fixtures is usually measured in footcandles; 1 footcandle is equal to 1 lumen cast per sq. ft. of surface. The amount of light outside on a typical sunny day can measure between 5,000 footcandles and 10,000 footcandles. In comparison, the average living room has about 30 footcandles of light. But it takes little light to make a big impact in outdoor lighting. For example, a full moon provides 0.2 footcandles of illumination but still gives most of us more than enough light to get around. Our eyes adjust well to the dark, so providing too much light can create a glare that makes it hard to see.
Exterior lighting should provide a gentle transition from darkness outside to brightness inside and vice versa. This is particularly important for older people. As we age, our night vision becomes poorer, and we have more difficulty determining depth.
Typical lighting levels in an exterior residential-lighting plan range from about 0.25 footcandles to 15 footcandles, although most plans won't require much more than 8 footcandles on one particular surface. Most lighting catalogs have charts that list the light output of their fixtures in footcandles. The actual number of footcandles required in any location will vary. If the surrounding area is fairly bright, more light will be required to illuminate a surface or object.
The reflectance of the object—how much light bounces off it and back to your eye—also affects the amount of light needed. A black-asphalt driveway requires more light than a white-concrete one does.
Lights spread out evenly along the driveway are always a good idea to keep guests from driving over the shrubbery. Aim for between 2 footcandles and 5 footcandles per fixture, depending on the brightness of the areas surrounding the driveway and the color of its surface.
Also, changes in direction, levels or ground surfaces along the path from the car or sidewalk to the house should be lighted to guide people to the front door. Ideally, sidewalks and paths should be evenly illuminated from fixtures along the path or overhead. Fixtures that perform best in this capacity cast a broad rather than a concentrated light over the path. Lighting that originates from trees or plantings at the sides of a path is also an option. Keep in mind that visitors will be most comfortable if light is directed toward the ground and not into their eyes.
Stairs are particularly important to consider when you're setting up lighting for safety. Options here include recessed lights installed flush with risers, in the walls on either side of the stair or just beside the tread. Post lights at the bottom of the stairs cast light across the steps and illuminate the transition from stair to walk but can be a potential source of glare because the light is at eye level.
Lighting can create an air of hospitality—
Lighting to ensure physical mobility is important, of course. You don't want neighbours tripping up your front steps or falling into your birdbath. But psychological ease is important as well.
A light over your front door illuminating the steps below shows approaching visitors where to go and welcomes them by directing them the safest way. Some of the options to choose from are shielded wall sconces at eye level; a single wall-mounted fixture above the door; a surface-mounted fixture on the porch ceiling; or down lights recessed in the porch or entry ceiling.
When patios are illuminated, they can become extensions of your house on warm evenings, drawing people outside. Shielded sconces that are mounted to the walls of the house can be used in combination with fixtures trained on nearby trees. Strings of tiny lights in a bush or even candles can light a small informal patio, while two or more different types of fixtures might be necessary to light a larger one.
Consider the different activities that take place on the patio. Conversation areas require only a low level of light, between 2 footcandles and 5 footcandles, but a barbecue area should be
Lighting creates a dramatic showcase for the garden. Trees, shrubs and walkways that are lighted at night can change the character of a garden, inviting strolls.
Path lights spread an even light over changing terrain. Partially shielded light fixtures illuminate steps and possible obstacles without causing glare, especially important on irregular steps.
A louvered 12v incandescent fixture illuminates the street address numeral from above.
Recessed into stairs, 12v louvered incandescents light up stair treads for safety.
Twelve-volt shielded path lights throw pools of overlapping light onto walkways.
Opaque glass lantern with warm-colored fluorescent or incandescent lamp adds a wel-coming glow to the entry.
Twelve-volt, 20w halogen direc- tional well lights illuminate the driveway for safety.
A low-key approach to exterior lighting. Exteriorlighting is most effective when paths, entries and landscape features are illuminated with low levels of light. If lights are too bright, the extreme contrast between dark and light makes it harder for your eyes to adjust and decreases your ability to see. Lights should be pointed down or away from viewers whenever possible. The drawing below illustrates some uses of typical fixtures; the choices of fixtures indicated are meant as examples.
Incandescent, metal-halide or mercury-vapor bullet lights can light ornamental trees and splash pathways with dappled light.
Mounted on exterior walls, shielded sconces with warm-col- ored fluorescent lamps graze the walls and light the porch area.
Incandescent down lights hung from the eaves at the edge of the patio shed more light on the barbecue area and graze the brick facade of the house.
Incandescent fixtures recessed into the porch ceiling warm an entry. A simple arrangement of lights illuminates the doorway and eases the transition between outside and in.
Lights and warmer weather can turn a patio into an extra room. Exterior lighting doesn't have to be fancy. These inexpensive Christmas-tree lights give a cozy feel to a small brick patio.
the interior. A dimmer switch on the interior light will help to balance the light between inside and outside.
Lighting the landscape also extends the perceived size of an outdoor space. People tend to feel more comfortable when they can see the things that are around them. Illuminating portions of the garden visible from paths and patios gives people a better idea of their surroundings, and it makes them more at ease. It also gives you the opportunity to show off the best features of your garden.
Trees and bushes with interesting branch patterns, leaf textures or shapes make good lighting subjects. Keep in mind that seasonal changes to foliage will change lighting effects. Different effects can be created by lighting the wall behind a tree, or lighting the branches and the foliage from below, from the side or from the leaves above.
To light a large area, Sarena McComas, a lighting designer with Rowland Design Inc. in Indianapolis, Indiana, positions fixtures in one or more trees high above the lawn. This technique works best in trees with sparse foliage and branches, and lighting from below works better on fuller trees.
She also suggests varying the types of landscaping lighting in the overall design. "If you use more brightly illuminated to make it safe and to allow the chef to see when the chicken's done. Recessed or surface-mounted can lights in the eaves, a light in a nearby tree or a post lantern near the grill will light the cooking area while the rest of the patio is illuminated by lights in surrounding foliage or smaller path lights around the perimeter.
Access to the patio from the interior should be lighted to a level between that of the patio and the room inside to give eyes a chance to adjust. Look for levels between 5 footcandles and 10 footcandles.
Landscape lighting improves the view from inside as well—Picture windows and patio doors reflect the scene inside when darkness falls, prompting many to close the blinds. Windows that offer views of the garden during the day continue to do so at night with the creative illumination of landscape elements. In these cases, the exterior lighting needs to be as bright as all one type of lighting, it's not as dramatic. Treat different areas of your yard differently," she says.
Lighting a house for security and avoiding the Sing-Sing effect—Many people want security lighting for their homes—bright lights that illuminate their property and foil potential burglars. Unfortunately, there's no proof that security lighting actually prevents crime, but lighting certain areas can make homeowners and guests feel more secure by making a residence appear occupied and by illuminating the grounds around the house sufficiently so that prowlers are visible.
Mark Schuyler, a lighting designer in Charlottesville, Virginia, believes that security lights may make it easier for thieves to do their work. When bright security lights became popular in his neighborhood, he and his neighbors noticed a sudden increase of burglaries.
Blasting the driveway or front yard with bright light can make it easier for a trespasser to hide in the dark. Because the bright light creates correspondingly dark shadows, your eyes have to work harder to adjust between the extremes of light; while your eyes are adjusting to the glare, you lose the ability to see in darker areas.
Lower light levels are often the preferable way to provide home security. Lights installed for safety or landscape illumination will provide good low-contrast light for the yard and approaches to the house. If you choose to employ bright lights in key security areas, a motion sensor switch controlling these bright lights will turn on the light only when activated, will save energy and will not spoil the effects of your over all lighting design. Another option is to control these bright lights with interior switches so that you can turn on the lights in emergency situations, during storms to check for fallen branches or if you suspect a prowler is on your property.
120v lighting is rugged; 12v systems are easy to install—There are two types of voltage used for landscape lighting these days, standard 120v household current and the increasingly popular 12v, or low-voltage, system. Although equal in energy use, each system has advantages. Household current is best used for larger permanent lighting applications. Because of the inherent danger of the higher voltage, 120v wiring must routed through conduit and buried in trenches 12 in. to 18 in. deep. Installations are usually handled by a licensed electrician, an additional but necessary expense. Although lower-wattage fixtures are not available for 120v systems, the higher voltage will support larger, higher-wattage fixtures in longer runs of wiring without a drop in voltage. For safety, these circuits should be GFCI-protected.
Low-voltage systems are generally less costly, easier to install and easier to relocate than standard-voltage fixtures. These systems can use incandescent or fluorescent bulbs, depending on the type of fixture used.
Low-voltage systems use a transformer to reduce standard household current, which is then conducted to 12v fixtures. Because the lower voltage is safer, wires can be run on the ground or in a shallow trench. Drops in voltage can be a problem when wiring over distances, so it's best to use low-voltage systems in runs of 150 ft. or less and not to overload the transformer. To make sure that the transformer will supply enough power, just add the total wattages of the fixtures; the transformer rating should be 10% higher than the total sum of fixture wattages.
You can buy either kits or individual components for a 12v lighting setup. Twelve-volt fixture kits are inexpensive and readily available, costing $30 and up at your local home center, and include low-voltage fixtures, wiring and a transformer. A larger transformer that will supply 100w, or eight fixtures of approximately 10w apiece, costs about $100; a 200w model's price goes up to about $160. Fixtures start in price at around $10.
Exterior fixtures must be sturdy and suited to the job—Once you've decided which voltage system to use, you need to choose fixtures. No matter which fixtures you choose, all should be rated for outdoor use and have watertight housings that are made of corrosion-resistant materials such as copper, brass or aluminum. Plastic fixtures are less expensive but may also be less durable, and they may degrade from exposure to heat and sunlight. Cracks in plastic housings can allow water into the fixture.
There are many types of fixtures on the market. Options include type of voltage (12 or 120), aesthetics (decorative or functional), types of attachment (post, wall mounted, hanging, recessed, etc.) and type of bulb used. Most fixtures are designed with a specific purpose in mind. For instance, bullet lights can be used in trees, near shrubs or in other lo- cations where the fixture will be inconspicuous and where you want a fairly bright light. Sconces and wall lanterns are available in a wide variety of decorative styles, but beware of glare; these fixtures are usually mounted at eye level.
Your local home center should offer some fixture choices, but be sure to check lighting suppliers for a more comprehensive selection. Manufacturers' catalogs can be a good source of information. Lighting designers can also help you to choose light fixtures. If you're about to spend a lot of time and money on a lighting installation, it's worth paying their fee to know
you're buying the right fixtures to achieve the effect you want.
Schuyler suggests trying out fixtures before you install them, dragging an extension cord across the lawn and positioning the fixtures as they will be in their final location. "You have to see what you like," he says. "It's hard to predict how lighting will appear before it's installed."