LIGHTING THE LANDSCAPE
Stay Dark and Stay Safe
by Joelle Steele
When you think about lighting a landscape, you are probably considering more than just how the plants and trees will look when lit at night. Even the least bit safety-conscious person will want a few little lights along the path to the front entry. But sometimes, the night lighting of a landscape can get out of control, even when done by a professional lighting contractor. And when things get carried away with lighting, the results can be not only unattractive but potentially dangerous.
LIGHTING UP THE SKY
According to David Crawford of the International Dark Sky Association, Americans spend $2 billion each year on energy that "does nothing but light up the underbellies of birds and airplanes." You've seen how brightly lit some homes, businesses, and neighborhoods are at night. Their lights shine up, down, and out, lighting not only the property they're on, but surrounding properties as well, sometimes shining brightly into a neighbor's windows — the latter being called "light trespass," which is illegal in some cities, counties, states, and countries. Then there are sensor lights that go on and off every time a gnat flies by. Tall pole lamps light up parking areas. Front porch lights shine clear out to the street.
All of this excess lighting can be seen from outer space and it's not really doing much at all to make a property safe and secure. No wonder astronomer and comet discoverer David H. Levy is so concerned about how much light Americans waste — light pollution — and how we are blocking our own views of the night sky while making our properties less safe by ignoring the basics of good security lighting.
To understand how to properly design a night lighting system for a home or business, it helps to first understand how we experience light at night, because that has a direct impact on how well a lighting system functions.
At night, each transition from a dark area to a light area or from light to dark requires that our pupils adjust to those changes in light levels. While pupils can adjust in about two seconds, they expand up to 8mm for young people, but only up to about 5mm for people around 40 and older. The older you get, the worse your night vision becomes.
But there is more than just the pupils involved in night vision. At night, your retinas rely on their rods — which detect dark and light. Those rods must also change their sensitivity if the light levels change significantly, like when you go from a dark street into a brightly lit intersection. The rods do not respond very quickly at any age. It takes them a full two hours to completely adjust to total darkness, and about a half-hour to adjust to total light! This means that in the dark, when entering a lighted intersection, parking lot, or driveway, the brightness is occurring far too quickly for your eyes to completely compensate and adjust to the lit area. This is why floodlights and any such overly-bright lighting do not provide security — they reduce your night vision, making it difficult for you to see the unlit shadowy areas in a landscape. The degree of illumination at night should never vary too greatly from the darkness. In other words, a little light goes a very long way at night.
SAFE AND SECURE?
Knowing how your eyes react in dark and light makes it easier to understand how a brightly lit property might not be all that safe. For example, you come home at 10 pm. You drive down a dark highway, turn into your own neighborhood where there are bright lights on tall poles at each corner, maybe even a light in between, and then you turn into your driveway which is brightly lit, possibly with a sensor or by a remote control that you operate. Maybe there's a front porch light on or even a light above your garage door. But what can you really see when your eyes are not fully adjusted to the light levels? Can you see a man dressed in dark clothing, standing on the sidewalk in front of the house? Probably not. Can you see that man if he is in your front yard, behind a shrub or tree, or standing at the side of your house? Definitely not — and he knows it!
With all that light, you'd think your house would be safe and secure. But according to Outdoor Lighting and Crime by Barry Clark, and the statistics cited in the Sourcebook Of Criminal Justice Statistics Online, most burglaries occur during the day when people are away from home. Statistically speaking, there is far more crime committed during the day than at night, and there is more crime in well-lit areas than in dark ones. And it makes sense. After all, criminals can't see any better in the dark than can their victims!
David Owen's 2007 article, The Dark Side: Making War On Light Pollution, points out that, in particular, unshielded floodlights actually help criminals see what they're doing and stop passersby and would-be victims from noticing the criminals are even there. This was also the finding of Professor Marcus Felson, School of Criminal Justice at Rutgers University. Felson concluded that the commonly-used unshielded floodlights and all-night lights both fail to prevent crime.
There is an enormous amount of supporting information for reducing lighting to increase security and prevent crime. Bruce Schneier has a blog called Schneier on Security. In 2007, he posted an excerpt from an article in the New Yorker Magazine that mentioned how in the early 1970s, the public schools in San Antonio, Texas, instituted a "no lights" or "dark campus" policy and removed and turned off lights at night on their buildings and parking lots. The end result: reduced energy costs, of course, but also a dramatic reduction in graffiti and other vandalism.
The concensus of the police in San Diego, California is that there is no perceivable influence of lighting on lowering crime. In Canada, the statistics of the City of Calgary Police Service concluded that most break-ins occur when buildings are unoccupied (e.g., homes in the daytime, businesses at night) regardless of the presence of security lighting.
Europe has also observed the impact of lighting on crime. A 2007 article in the Svenska Dagbladet (Swedish Daily News) stated that turning off the lights at night cut the number of thefts and burglaries in Övertorneå, Sweden by 50%. A study in West Sussex, England indicated that crime was up 55% in areas where all-night lighting was installed. A study of a high crime area of London that was fitted with 3,500 new streetlights stated that "... no evidence could be found to support the hypothesis that improved street lighting reduces reported crime." Also in London, The Home Office Crime Prevention Unit sought the criminal's perspective when they asked more than 300 robbers and burglars what most influenced their criminal decisions. Lighting was not a deterrent. This was also supported by the findings of the United States National Institute of Justice in their Congressional Report of 1997, which concluded that "The problematic relationship between lighting and crime increases when one considers that offenders need lighting to detect potential targets and low-risk situations." In other words, criminals like to work in the light.
Despite all this expert information, many people still think that bright lighting is going to make for increased safety and security. So what do they do? They buy floodlights! And why not? After all, they are bombarded with the advertising of lighting manufacturers who use scare tactics to sell more floodlights and motion detector lights. But, the truth is, floodlights don't provide security for you at all. It's the light quality, the amount of light, the angle of that light, the lack of glare, and the light fixtures themselves that determine how effectively a night lighting system provides security. And with lighting, the less you use, the safer you are.
LIGHT QUALITY AND AMOUNT OF LIGHT
For the greatest protection, a minimal amount of light is all that is needed for maximum security. This is because your eyes can only adapt to so much light at night, and the more light, the more glare, and that makes it much harder for you to see any danger, whether it's a criminal hiding nearby or an obstacle on the ground. Also, the brighter the light — as with floodlights — the darker the shadows, and the more hiding places created for criminals. Floodlights are generally quite cheap and readily available, and they are always sold as being great for security. They are definitely not. They are far too bright, create too much glare, direct light indiscriminately, and create deep shadows.
The very best lights or lamps for night lighting are low wattage (40-60 watts) low pressure sodium (LPS), not mercury-vapor, incandescent, metal halide, or halogen bulbs. Low pressure sodium provides plenty of light, no glare, and does not create dark shadows where intruders can hide. They don't blind anyone and they provide excellent visibility. Another option for lights in well-shielded fixtures is low wattage fluorescent, which offers an energy savings benefit as well as providing adequate security lighting.
Another option for night lighting is solar lighting. This requires no wiring at all and is the most energy-efficient option. But, in most cases, unless there is a solar panel on a rooftop that feeds power to the entire system, most fixtures will not receive enough direct sunlight to keep their cells charged. As a result, stand-alone solar lighting fixtures with bulbs that emit in the yellow range of the spectrum, and with shades/shields that direct the light downward, are only good options for lighting pathways.
ANGLE OF LIGHT AND LIGHT FIXTURES
Many, if not most, light fixtures waste almost half of the light they emit. This is because the fixture is placed incorrectly and/or lacks a shade/shield to direct the light at the proper angle, frequently sending it out horizontally so that it causes glare — which does nothing to improve visibility and security.
Start by selecting a low voltage lighting system, first for its safety, because should it malfunction for any reason, it will not shock you and, second, because it is cost-effective and relatively easy to install. Select lighting fixtures that are specifically designed with shades/shields that offer "full cutoff," which means that they direct the light only where it is required.
Pathways and Steps: To direct foot traffic, use small fixtures, no more than about 2' tall, that direct light onto the path or steps and that have a shade/shield which does not allow light to shine in any other direction. Place these fixtures at no less than six-foot intervals along paths and no less than three-foot intervals along steps.
Entries: For entry lighting at any door, place a fixture above the door or next to the door at a height of no more than 6' above the ground. Select a fixture that has a shade that directs the light onto the door area only. If additional lighting is needed for a large porch or patio area, put it on a separate switch so that it is only on when the rest of the porch is being used, and select a fixture that shines the light downward onto the porch and in no other direction.
Street Numbers: Select a small fixture that directs the light downward onto only the numbers.
Driveways: For entries to a driveway, most people prefer post lighting. Anything smaller tends to get run over rather easily. Entry posts should ideally be no more than 4' to 6' tall, and light fixtures should be mounted no higher than 4' to 6' from the ground. Select fixtures that have shades/shields that direct the light downward and onto the driveway only. Ideally, the spread of the light onto the driveway from the two fixtures should meet somewhere near, but not overlapping, the middle of the driveway.
Sides: For security at the sides of a house or building, mount motion detector fixtures at the corners, either under the eaves or on the wall itself no higher than 6' high up from the ground. Do not use floodlights. Use energy-efficient bulbs and shades to shine the light down onto the sides of the building, and down to the ground no more than 6' to 8' out from the wall.
Security always comes first. After that comes decorative lighting to highlight architectural or landscape design elements or features of a home or business. All of the information in the previous paragraphs applies to decorative lighting too. In addition, the angle at which decorative lighting is placed is dependent on what it is showcasing.
Backlighting: This technique is done by focusing a light fixture towards a surface (e.g., a wall, fence, or trellis) that is behind whatever is being highlighted (e.g., a fountain, specimen tree, sculpture, etc.).
Downlighting: This is your basic security lighting technique, but it can also be used to accent hardscape design elements such as decks, patios, paving stones, and ponds, or to accentuate small bedding areas.
Uplighting: This technique is done by placing a light in front of and below a landscape or hardscape feature (or a sign) in order to highlight it. Uplighting should never be misused or overused by making the light too bright or by shining it too far up or beyond the feature itself.
As you can see, night lighting is not as simple as just sticking a few light fixtures here and there and flooding a property with bright light. If you are a landscape contractor or a homeowner and you aren't sure how to design and install an appropriate and effective night lighting system, you should interview a variety of night lighting contractors and hire one who knows all the ins and outs of security and decorative landscape lighting. You don't really want to be one of the people who David Levy fears will one day have to tell their grandchildren: "Once upon a time there were stars in the sky that everyone could see."
This article last updated: 01/16/2016.