Lighting

There are many ways to save energy on lighting and, in some cases, improve the quality of light in agricultural facilities. New 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.

Illustration 6: Compact Flourescent Bulb.

Illustration 6: Compact Flourescent Bulb.

Indoor Lighting 

Production of standard incandescent lamps in the 40- to 100-watt range will be phased out in the U.S. by 2014. Specialty, 3-way, appliance bulbs and colored lights are exempt from the phase-out. Incandescent bulbs are the least efficient type of bulb, turning 90 percent of the energy into heat. Compact fluorescent lamps are four times more efficient and, in most cases, can be installed without any modifications to the fixture.

Illustration 7: Selecting the optimum bulb size is important. Source: Scott Sanford

Illustration 7: Selecting the optimum bulb size is important. Source: Scott Sanford

Outdoor Lighting 

Almost every farm has at least one outdoor “Yard Light”, Illustration 8. Many of these are 175-watt mercury vapor (MV) high-intensity discharge (HID) lights. MV lights are the least efficient of the HID-type lights. Metal halide (MH) and high-pressure sodium (HPS) HID lights are approximately two and three times more efficient than an MV lamp, respectively. MV and HPS lamps have poor color rendering characteristics (the ability for the human eye to differentiate colors using the lamp compared with sunlight), but MH lamps provide very good color rendering and are recommended for free-stall barns. Replacing the 175-watt MV yard light with a 100-watt HPS lamp could reduce outdoor lighting energy costs by about 50 percent and provide the same amount of light. Reflectors and timers can be installed to further reduce energy use and costs.

Illustration 8: Mercury vapor yard light. Source: Scott Sanford

Illustration 8: Mercury vapor yard light. Source: Scott Sanford

Yard Light Reflectors 

The typical yard light allows light to travel in almost all directions from the fixture. Light that doesn’t make it to the ground is lost. Hubbell, General Electric and RAB Lighting manufacture reflectors that direct the light emitted by the lamps to the ground, increasing the usable light by 47 percent and makes for good relations with neighbors (13). With more light on the ground, a lower wattage bulb can be used and still provide the same amount of light in the yard. For example, a 70-watt HPS fixture with a full cut-off reflector provides about the same amount of light as a typical 100-watt HPS or 175-watt MV lamp.

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 photo controller available that measures the length of the night and turns the light off during the second half of the night when yard activity is usually the lowest, saving half of the energy the light would normally use.

 

Figure 9: Full-cutoff Reflector.

Figure 9: Full-cutoff Reflector.

Long Daylighting 

When cows are exposed to 16- to 18-hour days, research has shown they give 4 to 5 pounds more milk per day (14, 15). Using artificial or a combination of natural and artificial light can create these long days. In a tie-stall barn this can be accomplished by installing a row of T-8 fluorescent fixtures over the feed alley. In a free-stall barn, metal halide or high-pressure sodium lamps are normally used unless the ceiling height is less than 10 feet, then high-output T-8 fluorescent fixtures are recommended. fixtures over the feed alley. In a free-stall barn, metal halide or high-pressure sodium lamps are normally used unless the ceiling height is less than 10 feet, then high-output T-8 fluorescent fixtures are recommended.