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Source: www.energy.gov

Exterior lighting is important for security as well as enhancing the overall appearance of any facility. While a lighting pattern for a parking lot or other outdoor space may seem simple, creating a lighting design that makes the best use of space can be complex. The ultimate goal is to optimize light levels and distribution, while minimizing power demand. Effective and efficient outdoor lighting should be a part of any security strategy. While proper lighting design alone does not ensure safety, it can be a valuable tool for increasing the overall security of your facility.

Brightest is not always the best

Insufficient light can compromise safety. As a result, many lighting designs focus on light output. While light levels are important, poor distribution can create over lighting in some areas and dark patches in others. "The conventional wisdom is that more light is better, but from a security standpoint, too much of the wrong kind of light, aimed in the wrong direction, can cause glare." according to Eric Richman, senior research engineer at the U.S. Department of Energy's Pacific Northwest National Laboratory. "Moreover, security camera function depends on various lighting factors including uniformity, contrast, light color and intensity. No one type of lighting will be best in all situations." (Lo Bosco 2012)

The Lighting Research Center at the Rensselaer Polytechnic Institute, conducted a study in Albany, N.Y., and New York City with various levels of outdoor lighting and found that individuals felt safe and secure at one foot candle. Anything more than that amount did not improve their impressions, according to John Bullough, a researcher at the Institute.

Lighting for safety and security

A good lighting design integrates the most effective light sources with proper height and location to obtain the best coverage. The Illuminating Engineering Society of North America (IESNA) is a leading authority on lighting design. The IESNA Lighting Handbook outlines the most important considerations for effective lighting for safety and security:

• Horizontal illuminance. The standard for assessing effective lighting because many tasks are horizontal in nature.
• Vertical illuminance. Critical for security issues because identifying objects and their movement is best done by viewing their vertical surfaces.
• Uniformity. Important for avoiding dark areas and enhancing the effectiveness of security cameras.
• Glare. Lighting aimed in the wrong direction can cause glare, reducing the visibility of occupants and security personnel.

To optimize savings and security, it is important to incorporate these design elements with an energy-efficient lighting strategy.

Energy-efficient outdoor lighting

So, how do you maintain a safe, secure environment while minimizing lighting costs? The most effective method is to combine energy-efficient lighting technologies with appropriate controls and operational practices.

Metal halide and high-pressure sodium lamps are the most widely used technologies for outdoor facility lighting. When lighting is scheduled for replacement, or an economic analysis supports an upgrade, install lower wattage lamps and fixtures in areas with excess light. One to three foot candles of illumination at ground level is typically adequate for security. A simple, inexpensive light meter can be used to measure light levels around your facility.

Consider light-emitting diode (LED) technology as an effective replacement option. LEDs are highly energy efficient and have a longer rated life than conventional outdoor lighting technologies. For security purposes, they offer potentially more distribution, whiter light for better contrast, as well as dimmability and instant start capability that is compatible with occupancy sensors. Wal-Mart conducted several tests using LEDs for outdoor lighting and eventually installed them at a new store in Leavenworth, Kan. The retailer surveyed its customers and found that they felt safe and secure with the new technology. (Hanford 2011)

In facilities with defined hours of operation, time controls can help you save energy without compromising security by switching some lights off or dimming them when the facility is closed. LEDs, with their dimming capabilities, are a good fit for this strategy.

For areas with intermittent occupancy, consider lighting controlled by occupancy sensors. The sensors activate all or part of the area when pedestrians or vehicles approach, providing safety and security while saving energy. Metal halide and high-pressure sodium lamps take up to several minutes to reach full lighting capacity and require a cool down time when turned off. LEDs or fluorescent induction lights, with their instant start capabilities, would be ideal for this application.

As with any investment, it is important to evaluate each technology as well as your specific lighting and security needs to make an informed decision. Be sure to check with local government officials about lighting regulations before exploring any lighting project; many local governments have adopted ordinances that define light level and types.

References

Hanford, Desiree. "Case Study: Exterior LEDs Balance Safety, Security And Green At Wal-Mart." Building Operating Management. December 2011.

Lo Bosco, Maryellen. "Excessive Lighting Does Not Improve Safety, Security." Building Operating Management. December 2012.

Richman, E.E. Exterior Lighting for Energy Savings, Security and Safety. U.S. Department of Energy. November 2009.