Lighting is a critical component of today’s supply chain real estate. The use of light, whether artificial or natural, affects the costs, labor, compliance and environmental elements of an industrial operation. Therefore, facility decision makers and designers should have a keen awareness of how light is employed in their facilities. This post reviews the importance of light, the most common types of lights, and the use of lights in industrial properties.
Why is Lighting Important
The choice of lighting type and location can have a significant impact on overall operating costs. In non-climate controlled warehouses, lighting is the primary electricity use accounting for 34% of total electricity use and an average of $0.12 per square foot per year in US warehouses.  For example, a 500,000 square foot warehouse at $0.12 per square foot per year in lighting energy costs will equate to $60,000 per year or $600,000 on a 10 year lease. In addition to the electricity costs, acquisition of equipment and maintenance is also a concern.
Light is also an important consideration in maintaining workplace productivity and employee satisfaction. Lighting has been shown to have an impact on the ability for individual workers to perform tasks, with poor lighting having a significant adverse effect on productivity, physical, and mental well-being. 
Lighting is also important to government agencies and regulators. Due to energy efficiency and safety concerns, U.S. federal, state, and local agencies have instituted guidelines and requirements for the use of certain luminaires, or complete lighting units, in non-residential real estate. For example, the California Title 24 California Code of Regulations regulates nonresidential indoor lighting in order to limit the energy used by lighting in a building.  OSHA also has minimum lighting levels for certain tasks, such as driving industrial trucks or forklifts.
Lastly, lighting is important for the overall environmental impact of an operation. It is now common for companies to track their impact on the environment through metrics such as corporate sustainability. The use of energy efficient lighting can be an integral part of efforts to lower a company’s carbon footprint, a key element in sustainability.
Types of Industrial Lighting
Industrial lighting generally falls into four different categories of artificial light sources and natural lights. Within each category are subcategories typically describing the application environment in which the light would be used. The table below describes each category by its energy efficiency in lumens per watt, average lifetime of the bulbs, and its general use. Warehouse lighting above storage areas are typically separated into high and low bay lighting. High bay lighting is used in 20′ to 40′ mounting heights where low bay lighting is used in 15′ to 25′ mounting heights.
|Incandescent||4-17 lm/w||2-20,000 hours|
|High-intensity discharge||50-200 lm/w||1,800-4,500 hours|
|Fluorescent||52-100 lm/w||8,000-20,000 hours|
|LED||10-110 lm/w||50,000-100,000 hours|
Table reference for energy efficiency and lifetime: 
Image source: http://www.energy.ca.gov
Incandescent lighting is the oldest lighting technology of the four categories above and the most inefficient, converting less than 5% of the energy they use into visible light. With the advent of fluorescent lighting sales in the late 1930’s, the use of incandescent lighting has declined.
Image source: http://www.zoro.com
High-intensity discharge or HID lamps are a type of electrical gas-discharge lamp which produces light by producing an electric arc between tungsten electrodes housed within a translucent tube. This tube is filled with gas and metal salts which typically give the lamp a name. Types of HID lamps include mercury-vapor, metal-halide (MH) lamps, ceramic MH lamps, sodium-vapor lamps, and xenon short-arc lamps.
Image source: http://www.zoro.com
A fluorescent lamp or tube is a low pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. It is much more efficient than incandescent lamps and has largely replaced incandescent lighting in industrial uses. Modern uses of fluorescent lamps in industrial properties include the T8 and more recent T5 fluorescent lamps. T8 and T5 are just codes to indicate that the bulb is tubular, hence the T, and the diameter of the bulb. T5 bulbs are 40% smaller than T8 bulbs, measuring 5/8″ in diameter versus 1″ for T8s. T5 bulbs are more efficient and have better lumens per watt than T8 bulbs, but they are also more expensive.
Image source: http://www.1000bulbs.com
Finally, light emitting diode or LED lighting creates light through electroluminescence via a two-lead semiconductor. LEDs were first produced in 1962 and now are used in a wide variety of applications, including increasing use in industrial properties due to their significant energy efficiency.
Use of Lighting in Industrial Properties
A well-designed lighting system is a critical component of a successful industrial operation. Since specific tasks within an industrial operation are varied, the appropriate lighting requirements for each task must be considered. First, the quantity of illumination must be sufficient for the task or process. Second, there must be enough light to create a safe operational environment. Third, listed or approved lighting equipment should be used. Fourth, a lighting fixture layout should be created which is sustainable and promotes safety. Last, the energy, economic, and operating characteristics of the lighting system should considered.
The quality of light is measured in several different ways. Illuminance is the amount of light falling on a surface and is typically measured in lumens. The amount of lumens is expressed as either lux (lx) or footcandle (fc) measurements, where lux is the lumens per square meter and footcandles lumens per square foot. In addition, the color of light can be measured in terms of temperature (kelvin) and a color rendering index, and described in terms of the color seen by the eye.
Calculating lumens is typically done with a light meter, such as the one below. It is important to note that the measurement of light at a point is dependent on the distance between the lamp and the point where the light level is calculated. In addition, light can be measured in vertical and even horizontal planes.
Generally, the more active the area, the higher the light requirement. For example, lighting in storage areas may not require as much light as shipping and receiving areas. According to the Illuminating Engineering Society of North America’s Lighting Handbook, inactive or infrequent areas of us should have 50 lx or 5 fc while active or frequently areas of use should have 100 lx or 10 fc. In addition, areas where employees commonly read large labels may require 100 lx or 10 fc and for small labels 300 lx or 30 fc.
In summary, lighting is an important part of any industrial operation’s productivity, safety, and efficiency. Light impacts the operating costs, labor, compliance and environmental components of the supply chain and therefore should be a concern of any responsible supply chain manager.
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