Poor visibility is at the core of lighting problems that may be associated with safety and security. Too much illumination and glare reduce our ability to see at night thus reducing both safety and security. Lights can make us feel more secure. The goal is to be more secure not to just feel more secure.
Two factors are key in using lights to increase the feeling of security and in not actually reducing security. Both factors increase visibility in the area. First, shield or position lights to eliminate or certainly minimize glare. Second, studies completed in 2013 show that reducing the amount of light, to about 25% of current levels, improves ones ability to see at night. The reduced amount of light allows the human eye to work properly after sunset.
Keep in mind that criminals need light too. Lighting can facilitate criminal activity by drawing attention to a property and permitting easy access. Criminals can hide when obscured by glare projecting into the eyes of neighbors or passersby. People and items are hidden when a floodlight is aimed so that the light from the fixture strikes your eye. People and items are visible when that same fixture is aimed so that the light is spread below the level of your eyes.
Many people believe that lights prevent crime. The National Institute of Law Enforcement and Criminal Justice that is part of the Unites States Department of Justice completed a large study on the impact of street lighting and crime. It determined that there is no statistically significant evidence that street lighting impacts the level of crime. However, there is a strong indication that increased lighting decreases the fear of crime. Shielded lighting that does not produce glare and is not so bright that it produces dark shadows could promote safety and security. Unfortunately, many individuals, groups and lighting manufacturers have proliferated the flawed belief that good security demands large unshielded flood lights for so long that most people take it as truth.
Security issues are best addressed with measures other than lighting. More effective and less expensive security measures include: using adequate locks, and having an effective alarm system. To use lights to improve security, the most effective means is to provide a sudden change to the surrounding environment. Motion sensor governed security lighting that turns on when someone approaches an area may attract attention and drive away someone with criminal intent. To prevent a reduction in visibility, even these sensor-governed lights should be shielded and installed so that they neither produce glare nor a severe difference between the illuminated area and it’s adjacent area.
In summary, unshielded or improperly aimed security lighting can actually reduce security by producing glare and brightly lit areas that conceal persons with criminal intent. Any glare created by these so-called security lights will limit the ability for anyone to see onto the site. A light used for safety or security must keep the bulb or refractive lens shielded and be of the lowest amount of light possible to do the job. Passersby who see people in over lighted areas usually presume they belong there and the over lighting creates dark shadows at the edges of the light. Keep in mind that if there is no one present to see the criminal all the light will do is attract the criminal and provide light for the criminal activity.