Good lighting is important for farm security, for being able to adequately do indoor chores, for certain aspects of livestock performance, and even for employee and operator morale. Farm lighting may also be an area where some upgrades to the lighting technology or doing some routine maintenance and cleaning could result in some increased lighting performance, efficiency and possibly some reduced costs. I recently came across a good article on the eXtension web site entitled “Farm Lighting Energy Efficiency Checklist and Tips” that provided material for this column. The entire article can be found on-line at: http://tiny.cc/eXtensionfarmlighting . There are some very good publications from the University of Wisconsin Extension (click on the titles for a pdf document); one entitled “Energy Efficient Agricultural Lighting” and another entitled “Lighting Technology: LED Lamps” that also provided information used in this column.
The first point that needs to be made is that the more hours/day a light is used the more likely it is to show an economic return for replacing it with a more efficient fixture or lamp. Concentrate on applying the following suggestions on lighting that is used for multiple hours every day rather than the occasional use or 1-2 hour/day lighting situations.
Lamp output is measured units of foot candles, or lumens. Light efficiency is measured by the amount of lumens produced per watt. Based on this measuring stick, incandescent bulbs are the least energy efficient source of lighting. Other lower efficiency lighting includes halogen and mercury vapor lamps. Light emitting diode (LED), fluorescent lamps, high pressure sodium and metal halide lamps are examples of higher efficiency lighting. Replacing incandescent bulbs with a more energy efficient lamp almost always makes economic sense but sometimes swapping out a T12 fluorescent lamp with a more energy efficient T8 fluorescent lamp could save dollars. Just for clarification, the diameter of a fluorescent lamp is denoted in eights of an inch; so a T12 is 12/8’s or 1.5 inches in diameter while a T8 is 8/8’s or 1 inch in diameter. Determining which specific higher efficiency lamp to use requires consideration of the quality of light needed the intensity of light needed and the environment in which the light will be operated.
The quality of light emitted is typically measured by some kind of scale that compares the lamp light to sunlight. One of those scales is the color temperature index (CCT), which is a description of the color of the light emitted. A lower value indicates an orange/red light and a higher value a “bluer” light. For example, high pressure sodium light is assigned a value of 1900, an incandescent bulb a value of 2800 and a daylight simulating fluorescent lamp a value of 5000. Another scale is the color rendering index (CRI) that assigns a value from 0 to 100 to a lamp based on the perceived color of an object under that lamp as compared to viewing that object’s color in sunlight. Under the CRI system a low value means that it would be hard for a worker to differentiate between colors under that particular lamp. As an example a mercury vapor lamp would have a low CRI value while an LED lamp would have a CRI value of 90 or greater.
The intensity of the light needed will depend upon the job or task that needs to be done. Detailed or precision work requires a higher light intensity than lighting for storage or security reasons. Some farm examples of suggested foot candle light intensity values depending upon the task include: 15-20 foot-candles in a free stall barn, 50 foot-candles in the milking parlor at the cow’s udder or at the desk top of a farm office, 100 foot-candles at a washing sink or for egg packing and inspection, 10 foot-candles for machinery storage.
Finally lighting needs to be considered in terms of the environment in which it will operate, specifically regarding temperature, dustiness, and humidity or moisture conditions in farm settings. If you are replacing lighting, make sure the new lighting is designed for the environmental conditions it will experience. The use of compact fluorescent lamps may be limited in some areas because depending upon their rating they can require a minimum starting temperature of either 32 F or 0F and at low temperatures may require several minutes to fully illuminate. On the other hand, LED lamps are cold loving and can actually increase their light output as temperature drops from 75 F to minus 20 F. Lamps installed in areas with prolonged exposure to moisture should be housed in fixtures with moisture resistant ratings. Dust absorbs light waves and reduces light output. Accumulating dust can also reduce the ability of lamps and fixtures to dissipate heat, which can reduce lamp life. Taking the time to regularly clean lamps and fixtures that operate under dusty conditions can extend lamp life and keep light output at higher levels.
The use of timers, photo sensor and motion detectors are tools that can be used to use lighting more effectively and efficiently. These tools can insure that lights get turned off when they are not needed and are on when they are needed.
For more information about farm lighting contact the Wayne County Extension office at 330-593-8722, check out our web page at http://go.osu.edu/agwayne, or consult directly with a lighting specialist.