A Lighting Designer's Musings on Security Lighting

a guest post by Lisa J. Reed, Lighting Designer

What kind of light makes you feel most secure? Daylight. Shadow-free light. Light that allows you to see and recognize the people and/or any potential hazards around you. What are some ways of replicating this sense of safety at night? Is more light always better? Crimes are sometimes committed in the middle of the day; so obviously lighting isn’t the only crime deterrent.

Security lighting can be defined as: lighting designed to protect against deliberate attack. Given that, I would further define it as lighting that makes people feel secure by allowing them to see the expression on a stranger’s face, to see well in the peripheral zone of vision, and at the same time is not a source of glare or discomfort.

Use White Light

Research has shown that white light allows people to see better at night and also improves visual acuity in the peripheral zone of vision. That rules out the use of sodium lamps or colored LEDs for security lighting.

Keep it Even

Because our eyes have to work hard to adjust to different light levels, a very brightly lit entrance with a dark surround can be uncomfortable. A lower light level with even illumination feels safer than a mixture of bright and dark areas.

Vertical Footcandles

Inexperienced lighting designers will calculate the number of footcandles on the ground. But when you are walking across a parking lot and a stranger approaches, you don’t care what kind of shoes they are wearing. At that point, you want light shining onto the stranger’s face – you want vertical footcandles.

When our designs are totally focused on the number of footcandles on the ground, we may not achieve the best security lighting. See the photos below. In the daytime photo the “people” in the sculpture are easy to see. But look at the nighttime photo. There is plenty of light on the ground, but the people are nearly invisible.

In the daytime photo the “people” in the sculpture are easy to see. But look at the nighttime photo. There is plenty of light on the ground, but the people are nearly invisible.

Motion Sensors
The use of occupancy sensors not only saves energy, but can also contribute to security. Consider the lowly residential motion light. When it is on, you know someone or something is in the driveway. It announces the arrival of guests. In the past, the use of HID sources in commercial applications has prohibited the use of motion sensors because of the long restrike time. However, the advent of LED as a viable outdoor lighting source opens a world of energy-saving opportunities and potentially even better security by adding the element of surprise. A panic button or interior switch can be added to the circuit to provide some level of occupant control.

Design
Make the security fixtures small and/or make them blend with the building. These fixtures can be ugly, but they don’t have to be. Select one that has some style. Better yet, make it blend in with the building so well that the casual observer can’t even see it. At the very least, paint wall mounted fixtures to match the wall on which they are mounted.

Those are my musings on security lighting. What do you think? Can security lighting do the job and still be a good-looking part of a building or space? What are your security lighting challenges?

 

Lisa J Reed photo - Lighting Blog

Lisa J. Reed has been attracted to lighting (like a moth to a flame) for 20+ years. She is the Founding Principal at Envision Lighting Design, LLC in St. Louis, where she designs, teaches, and writes about architectural lighting. Connect with Lisa J. Reed on Google+.

 

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