Benefit #1: Glare Reduction
Glare reduction is the most important benefit of effective nighttime lighting.
Defination of Glare:
Glare comes in three forms (adapted from IESNA RP-33-99):
1. Disability Glare - Also known as veiling luminance, disability glare is caused by lights that shine directly into one's eyes. Disability glare is dangerous because it is blinding.
2. Discomfort Glare - Discomfort glare does not necessarily reduce the ability to see an object (as is the case with disability glare), but it produces a sensation of discomfort. It is caused by high contrast or a non-uniform distribution of light in the field of view.
3. Nuisance or Annoyance Glare - Nuisance glare is defined as glare that causes complaints, such as the "light shinig in my window" phenomenon.
Comments on Glare:
Glare is a significant and pervasive problem. See this example of extreme glare.
Glare demands attention. Your eye is naturally attracted to the bright light. This is dangerous while driving but glare can be used by retail establishment to attract attention of consumers passing by. This can lead to competion between business to get noticed.
Older citizens are extemely sensitive to glare. See this report on the aging eye.
Many people equate glare with light! Just imagine if a bare light bulb was hung in the middle of your living room or office. People would get upset pretty quickly! But this is exactly what happens with most of the night lighting installed today. Effective night lighting eliminates glare and illuminates the target resulting in much better "seeing" conditions in the nighttime environment.
Solutions to Glare:
Fortunately, the problems associated with glare are easily solved by installing shielded or full cut-off light fixtures. These fixtures are no more expensive than poorly designed lighting and most lighting manufacturers have a line of fully shielded fixtures.