Lighting – There are many opportunities with lighting to save energy and in some cases, improve the lighting levels in dairy facilities. Many facilities are under lit but with the many types of new technology lighting, the lighting can be improved while many times not using any additional energy because the newer lighting technologies provide more light output with less energy. Light maintenance is also reduced with the new lighting technologies because they also have longer life.

• Indoor lighting – Many dairies are still using incandescent bulbs or T-12 Fluorescent lamps that flick when the cooler weather sets in. In most cases, the lamp of choice today for agricultural buildings is T-8 fluorescent lamps in water resistant enclosures. These lamps have a temperature operating range down to 0°F without flickering, output about the same light as the favored T-12 fluorescent lamps but use 20% less electricity and the lamps last 65% longer — a win-win situation. Compact fluorescent lamps (CFL) are designed to be a direct replacement for the old faithful incandescent bulb which is the oldest and least reliable of the lighting technologies. CFLs use 25% of the power of incandescent lamps and last 6 to 10 times longer. If used in high humidity conditions, they need to be housed in a sealed fixture like a jelly jar.
• Outdoor lighting – Almost every farm has at least one outdoor light – The “Yard Light”. Many of there are175 watt mercury vapor (MV) high intensity discharge (HID) lights. Mercury vapor lights are the least efficient of the HID type lights. Metal Halide (MH) and High Pressure Sodium (HPS) HID lights are approximately 2 and 3 times more efficient than a MV lamp. The MV lamps have poor color rendering characteristics (the ability for the human eye to differentiate colors as compared to sunlight), about the same as HPS lamps which MH lamps provide very good color rendering. Replacing the MV yard light with a HPS lamp could reduce your outdoor lighting costs by about 50%.
  • Yard Light Reflectors – The typical yard light has a refractor that allows light to travel in almost all direction from the fixture. Light that doesn’t make it to the ground is lost. Hubbell and GE manufacture reflectors that focus the light emitted by the lamps to the ground which increases the usable light by 47% and makes for good relations with star gazing neighbors.
  • Half Night Light Controllers – The typical dusk to dawn yard light uses a photo controller to turn the lamp on at dusk and off at dawn. There is a new photo controller available that measures the length of the night and turns the light off the second half of the night when the least amount of activity is usually occurring, saving half of the energy the light would normally use

  For more information on lighting refer to UW Extension Bulletin A3784-14: “Energy Efficient Lighting for Agriculture“.

• LED Lighting – is a newer type lamp that has many advantages over all other lights. They are very energy efficient with some lamps with efficiency of 140 lumens per watt compared to the Edison bulb at 15 lumens per watt. They have long life, 25,000 hours for a household type lamp to over 200,000 hours for some wide area lamps. LED lights are also cold loving, emitting 10% more light at -20F than at 70F so no more dimly lite barns during the winter. They also don’t contain any mercury or other hazardous materials and are very durable. Over the next 5 years there will be a major shift to LED lamps/bulbs for general purpose lighting due to their excellent light quality, long lamp life and no disposal issues due to hazardous materials.
  For more information on lighting refer to UW Extension Bulletin A4050: “Lighting Technology: LED Lamps for Home, Farm and Small Business”

If you have questions about the information on this site, please contact
Scott Sanford, Distinguished Outreach Specialist, University of Wisconsin, sasanford@wisc.edu.