Looking at Outdoor Security Lighting Basics|
Article- August 2013 By Larson Electronics.com
Larson Electronics 40 Watt LED Sensor Light
Security lighting has been an area of great growth as well as contentious debate within the security and lighting industries. Prior to the World Wars, attention to outdoor security lighting was given little importance, and most outdoor lighting served as basic illumination for more utilitarian purposes. Post World War society however was much changed, and emphasis began being placed on lighting as a deterrent to crime and even possibly subversive activities by foreign operatives. While its effectiveness against the latter was never really a major source of discussion, the ability of illumination to act as a crime deterrent has indeed been the subject of much debate.
Many studies have been performed in an effort to determine the effectiveness of lighting in reducing the instances of violent crimes, burglary and robberies. Many of these studies are at odds with each other, which has served to only increase the confusion around security lightings’ effectiveness rather than produce a definitive answer. Much of the problem seems to stem from how the performance of security lighting is measured and the parameters against which it is evaluated. For instance, it is not enough to consider how brightly illuminated an area is, but also how well objects can actually be seen, and how the lighting affects the ability of observers outside of the illuminated area to view the area being illuminated. A very bright perimeter lighting system for example might indeed illuminate a fence line very well, but when observed from a position outside of the illuminated area, the observer may find it difficult to accurately view the entire area. The area might be brightly lit, but heavy glare, poor lighting color quality, and poor fixture placement creates areas where objects are obscured, contrast and detail is washed out making objects blend into the darker background, and dark zones provide areas to avoid visibility.
Because of our natural propensity for avoiding dark places when alone, an understandable behavior considering the inability to see a potential threat greatly increases the chances of becoming a victim, being able to illuminate an area increases our feelings of security and safety. Since we naturally associate well lit surroundings with a higher degree of safety, it of course follows that outdoor lighting would thus become viewed as a common sense way to improve security. The problem though is that the feeling of security that illumination provides is not always valid. While holding the potential to reduce the incidence of criminal activities, illumination can also actually serve to increase their number as well. As counterintuitive as this may seem, this is borne out by the aforementioned studies, which is why there is some controversy over the effectiveness of outdoor security lighting.
Although this idea that lighting can both hinder and facilitate criminal activity can seem confusing, once we look at how this happens it becomes clear why this is. Security lighting really serves three main purposes that serve as better focal points for evaluating its effectiveness than just relying on the feeling of confidence it instills. These focal points include to act as a deterrent to the would be criminal who is relying on not being seen to facilitate his activities, to help the law abiding citizen identify and avoid potentially dangerous situations, and to help in the identification and description of criminals and their activities should deterrence fail. Security lighting also serves to provide general illumination for normal activities and improve the public’s general feelings of security and confidence, thus increasing their presence around well lit areas and as a result potentially reducing the incidence of crimes that rely on remaining hidden from view of the public.
In order to act as a deterrent, security lighting must serve to make it more difficult to engage in criminal activities. The primary way lighting accomplishes this is by making it difficult to remain out of the view of outside observers. However, in order for this to be effective it must indeed be possible for potential observers to view the illuminated area, otherwise lighting can serve to increase the chances of an incident. A case in point involves a school in Texas which for several years experienced frequent instances of vandalism. The school grounds were well lit, but the ability of observers made up of the local community to actually view the grounds was severely limited by distance and obstruction. The school eventually began turning off the lighting and allowing the grounds to remain dark throughout the night. In this case, the instances of vandalism dropped dramatically, indicating that lighting was actually helping the vandals in their activities rather than deterring them. Thus, a remote building that is not within reasonable viewing range of nearby observers is likely not a good candidate for outdoor security lighting as such lighting would only serve to increase utility costs and make it easier for criminals to engage in their activities.
Placement of lighting is also extremely important when utilizing lighting for security purposes. Attention must be given to potential obstructions that may provide areas of darkness ideal for obscuring activities. Additionally, lighting needs to be properly spaced so that overlap is not too great and irregular patterns of brightness and darkness created. The goal is to place lighting so that illumination is uniform and even over the entire targeted area. It is likewise important to consider the glare created by fixtures which might interfere with an observer’s ability to view an area. Fixtures with poor directional control and lamps that are easily within direct line of sight tend to create bright glare that can make viewing the area illuminated by the fixture difficult. This problem is most common with metal halide wall pack fixtures, which tend to have the lamp and reflector assembly facing outwards from the side of the fixture, with no hood or shield or in place to help control beam spread and block the lamp itself from the outside observers viewing angle.
For final consideration, the quality of the light being used also plays an important role in security lighting’s effectiveness. If you have ever been in a parking lot illuminated by low pressure sodium lamps you are familiar with how the reddish orange coloring of the light interferes with the ability to discern colors and details. Lighting with poor color quality and low color temperature tends to make it difficult to discern contrast and detail while also making it difficult to see the actual color of objects being illuminated. A blue car under a low pressure sodium lamp for instance will appear to be black in color, while a yellow car may appear to be maroon or even red. Because of this, security lighting should be fitted with lamps of high color temperature and good color rendering index in order to allow observers to make the most accurate and detailed observations possible.
In order to effectively utilize security lighting it is very important to remember that it is not so much the fact that an area is illuminated that makes it effective, but that the area can first actually benefit from illumination, and second that this illumination is properly chosen and installed. Security lighting when improperly installed or used in areas where it will not facilitate the observation of the illuminated area can actually increase the problems associated with criminal activity. In the end, first making sure an area is indeed visible to the surrounding citizenry and then ensuring that this lighting provides them with the best viewing opportunities can make all the difference between lighting that wastes money and lighting that improves the security and safety of the properties in question.