Evaluate your parking lot lighting

2019-09-03

If your facility was built more than a decade ago, your outdoor safety lighting may not be enough. Lighting for parking lots and other outdoor areas has not been a top priority for lighting designers for many years. In many cases, the purpose of outdoor lighting is to enhance the appearance of the building rather than providing safe and reliable lighting.

It is recommended that each security manager perform an external lighting assessment of the facility in charge of it. Adequacy of outdoor lighting is an important factor in maintaining good safety in parking lots and other outdoor areas. The lack of external lighting is the basis of many litigations that claim that facility owners are negligent in providing appropriate security.

Basic considerations

The design of the lighting system is a highly technical science that requires years of training to learn. While most security managers are unlikely to be lighting experts, there are some basic lighting designs that are important to every security manager. Understanding this basics will enable security managers to accurately assess the lighting systems used in their parking lots.

There are five basic considerations when evaluating a lighting system:

Lighting intensity: How bright is the light?

Lighting uniformity: How does the light level of the entire lighting area remain the same?

Lighting color: How accurate is the color of the lighting rendering?

Lighting efficiency: What is the amount of electricity per watt provided by the lighting system?

Lamp life: How long does it take to replace the lamp?

Conducting lighting surveys

The first step in evaluating an existing lighting system is to determine the type of lamp currently in use, To fully understand how to benefit from the new lighting system. Outdoor parking lighting systems typically use five types of lights:

Mercury vapour: Typically used in facilities built in the 1960s and 1970s. The color is not performing well; it emits a blue-green light. The lamp life is very good, but as the lamp ages, the lamp brightness is significantly reduced. All types of lamps are the least efficient in terms of energy usage.

Low pressure sodium: poor color reproduction; emits orange-yellow light. Lamp life is relatively short, but as the bulb ages, the light decays very little. The most effective type of lamp for energy use.

High pressure sodium: The most commonly used type of bulb in the 80s and 90s. The color is not performing well; amber amber light is emitted. The lamp has the longest life and the light level is reduced the least when the lamp ages. Very effective in energy use.

Metal halide: excellent color performance; emits almost white light. The lamp life is moderate. More effective than mercury vapor, but less efficient than low pressure sodium or high pressure sodium in energy use.

The type of luminaire used in your plant can usually be determined by asking a maintenance person or lighting contractor who will service your lighting system.

The second step in evaluating an existing lighting system is to measure the illuminated area to determine the level of light present. The level of illumination is measured in feet of candlelight (fc) or its metric equivalent (lux (lx)).

To accurately measure the level of light, a light level meter is required. Suitable photometers have a range of at least .1 fc to 25 fc. You can buy a light meter relatively cheaply (less than $400) or borrowed. (Note that most illuminometers designed for photographic use are generally not suitable for lighting system evaluation - they give inaccurate readings at lower brightness.)

Get or draw an accurate map of the area under test before starting the light level measurement. For ease of use, maps should be drawn on a standard building or project scale. If it is not already displayed on the map, draw the location of all existing poles and fixtures and any other important features in that area.

Start the lighting survey at one end of the area. Place the photometer in front of you to make sure it is not blocked by any part of your body. Read and write it on the map to indicate where you are. Continue reading at approximately 10 to 20 feet intervals throughout the area you are measuring. In addition, be sure to read the readings on all channels and walkways between the survey area and the entrance to the adjacent building.

Evaluate your results

There is a lot of debate about what constitutes "sufficient" lighting in parking lots or other outdoor areas. Published standards show that the acceptable level of illumination for parking lots can range from a minimum of 0.5 fc (low activity area) to a high of 5 fc (high activity areas where pedestrian safety is of concern).

For the parking area, Adiding recommends a minimum light intensity of 1 fc for the entire area, ideally 2 to 4 fc.

Equally important is the uniformity of illumination throughout the region. The uniformity of illumination is expressed as the ratio between the lowest light level reading and the average light level reading over the entire area. For example, if you are shooting an average brightness reading of 5 fc and your lowest brightness reading is 1 fc, the uniformity ratio is 5:1. Adiding recommends a maximum uniformity of 3:1 for most outdoor parking applications.

Many of the parking lots we surveyed are far below the recommended light standards. It is not uncommon for many parking facilities to have an average brightness of .3 fc or less. More importantly, the lighting uniformity of many parking lots is very poor.This will be reduced if parking lot lighting is installed in a suitable location.

It is not uncommon to see a uniformity of up to 200:1! Typically, high brightness (20 to 30 fc) is found directly under the luminaire. When you get out of the luminaire, the brightness of the light is reduced, and at the midpoint between the luminaires, it is not uncommon to see a light level of .1 fc or lower. Lack of uniformity is usually caused by luminaires that are too far apart. The situation becomes complicated when trees or other types of landscaping are located between fixtures.

Improve lighting
 

If your survey shows insufficient light levels or uneven lighting levels, you should consider improving parking lot lighting. Adiding recommends that you contact a qualified lighting engineer to help you determine which specific improvements should be made.

Here are some other things to consider:

If your facility is currently using mercury vapor or low pressure sodium lamps, you should consider replacing them with high pressure sodium lamps or metal halide lamps. In many cases, the cost of replacing these old bulbs can be quickly restored by continuing to save bulb replacement or reduce energy costs.

Metal halide lamps are the best lamps for safety purposes. This is because metal halides produce nearly white light that clearly distinguishes colors, making it easier to correctly identify people and vehicles. White light produced by metal halides appears to be more natural and, in our opinion, has a greater deterrent effect than illumination produced by other types of lamps.

Outdoor lighting plays a vital role in the way closed-circuit television (CCTV) systems work in outdoor environments. While most modern CCTV cameras work at relatively low light levels, the uniformity of illumination is important. If the illumination uniformity ratio is too high (greater than 5:1), the image viewed by the camera is of poor quality with both "hot spots" (bright glare areas) and "cold spots" (dark areas) where there is no detail). If you use a color camera outdoors, the color of the lighting is also important. Using a lamp other than the metal halide type may result in an incorrect color seen by the camera.

The type of light fixture used largely determines how the light of each light fixture is distributed. Many of the older types of light fixture used for parking lot lighting are very inefficient, and most of their light levels are projected upwards rather than downward toward the surface of the parking lot. Replacing light fixture with more modern types or adding "canopies" (hoods) to existing light fixture can greatly increase lighting brightness and light fixture efficiency.

Many towns have enacted “light pollution” regulations. These regulations usually set limits on the amount and type of light that can be used for outdoor parking lot lighting. Be sure to consult the jurisdiction of your area before making any changes to the lighting system.

Outdoor lighting fixtures require regular maintenance. As you age, the light from the bulb tends to decrease. Replace the bulb at predetermined intervals - not just when the bulb burns out. Dirty lighting fixtures also produce less light. Arrange for regular cleaning of the fixtures both internally and externally.

The growth of trees and other types of landscapes can have a major impact on outdoor lighting. Often, a well-designed lighting system can become ineffective because trees grow up to block most of the light. Arrange the trees and landscapes regularly to avoid adverse effects on the lighting system.