Dairy lighting system for tie stall barns

Summarized by Milkproduction.com staff from: AEU-13, University of Minnesota, U.S. Department of Agriculture, and Minnesota Counties Cooperating

Unit Conversion:

1 lux = 0.09290304 foot-candle and 1 foot-candle = 10.76391 lux

Design process

Proper lighting starts with an effective design. The design process consists of three steps:

1. Determine the illumination level required for a given area or task.
2. Select the type of lamp best suited for that area.
3. Determine lamp size and spacing.

STEP 1

Determine required illumination levels

Light intensity is measured in lumens. The unit of illumination in the English system is the foot-candle (fc). Illumination is the amount of light striking a surface at some given distance from the light source. In the metric system illumination is measured in lux (lumen per square meter). One foot-candle is equal to about 10 lux.

Table 1 Recommended illumination levels for tie stall barns.

In dairy barns, the lighting requirements to stimulate additional feeding activity that results in increased milk production must provide the following: (1) 10 to 20 foot-candles of illumination in the feeding area of the barn, (2) a 16 to 18 hour time period at this level of light, and (3) a continuous dark period of 6 to 8 hours. Providing illumination for 24 hours a day does not yield any additional production or animal health benefits when compared to 13.5 hours of illumination.

STEP 2

Select type of lamps

Types of lamps that are available include: incandescent, fluorescent, and halogen. Because of their efficiency, fluorescent lamps are recommended for most areas of tie stall milking barns. The most important characteristics for each lamp type are listed in Table 2.

Table 2 General characteristics of common light sources

Lamp Efficiency
The efficiency of a lamp is expressed as the amount of light provided per unit of input energy, or lumens per watt. Lamp efficiency usually increases with lamp size.

Lamp Life
Lamp life is the time a lamp operates at its designed level. The more energy efficient lamps also have the longest useful life.

Starting Temperature
Starting temperature is generally only important when selecting a lighting system for a cold environment. Incandescent lamps perform well at cold temperatures (-20°F). The minimum starting temperature for most fluorescent lamps is 50° F, except those equipped with cold starting ballast.

Warm-up period
Incandescent and halogen lamps do not have a warm-up period. Fluorescent lamps have a slight starting delay, but it is not significant. All of the high intensity discharge lamps have a significant warm-up period which can range from 1 to 15 minutes.

Color

The color, or degree of whiteness, of a light source is defined by the color rendition index (CRI). A CRI of 80 or more is required for color matching tasks.
The quality of the light in a work area must be considered in addition to the quantity and efficiency. The quality of the lighting installation is not only influenced by the color of the light source but also by the light uniformity, spacing, glare, and reflectance of the surfaces in the room.

Glare is the result of excess light that is in the normal line of sight in the work area. Glare is defined as any brightness in the field of vision that causes discomfort, reduction in vision, or eye fatigue (ASAE, 1993). Glare may come directly from the fixture or be reflected from a glossy surface. Fixture positions and surface reflectivity influence the amount of glare. Fixtures should be mounted above the line of sight to reduce glare.

Table 3. Floor area per fixture (ft2/fixture) needed for general area lighting using fluorescent lamps (T8 only).

Table 3a. Floor area per fixture to provide 10 fc of illumination.

Table 3b. Floor area per fixture to provide 20 fc of illumination.

Table 3c. Floor area per fixture to provide 50 fc of illumination.

STEP 3

Determine lamp size and spacing

Once the illumination level and type of lamp have been determined, the next step is to determine the area each fixture will illuminate. This section contains a set of design tables to assist in designing the lighting system. These tables were developed based on lamp data from several manufacturers, in-service performance data of Chastain (1994), the design methods described by MacDonald and Henderson (1991), and Frier (1987). The tables establish the floor area each fixture will illuminate based on mounting height and type of lamp.

For most areas in the tie stall barn illumination levels of 10, 20, or 50 foot-candles (from Table 1) are required. Fluorescent lamps are recommended for all of these areas. Table 3 shows the design values for fluorescent fixtures. Use this table to determine the floor area per fixture for a given illumination level, mounting height, and lamp size.

The ratio of the fixture spacing to the mounting height determines the uniformity of light in a work area. A high level of uniformity is required in an intense work area such as the alley behind the cows. This level can be achieved by using a fixture spacing to mounting height ratio of one. For example, space the fixtures 8 ft apart or less if the mounting height is 8 ft. Highly reflective wall, ceiling, and floor surfaces will enhance the uniformity of illumination.

Very little natural light is available in the manger area of tiestall barns. A fluorescent lighting system that provides at least 10 foot-candles should be installed over the manger alley. The lights over the feeding area should be controlled by a timer in order to control the photo period precisely and save energy.

Bulk tank inspection and veterinary treatment

Reference to Table 1 indicates that bulk tank inspection and veterinary treatment require 100 foot-candles of illumination. These tasks also require the highest color rendition (CRI = 100). Lighting for these areas is best provided by directing light toward the work area using halogen spot or flood lamps. Halogen lamps provide the best combination of lamp life, color rendition, and efficiency (Table 2).

Halogen flood and spot lamps are an inexpensive way to provide the required illumination in these work areas since they are relatively small. The lighting level of a spot or flood lamp is often rated in terms of candlepower and not lumens. The illumination level in foot-candles can be estimated from the rated candlepower of the lamp and the distance from the lamp to the work area. Table 4 gives the required information to select halogen lamps to provide 100 foot-candles of illumination at distances from 40 to 190 inches.

Use a single narrow spot lamp for bulk tank inspection that is mounted to the side of the inspection port of the bulk tank. Mounting the lamp to the side will prevent pieces of a broken lamp from falling into the bulk tank. Use a ceiling mounted fixture that allows the beam of light to be aimed into the bulk tank.

Two or more spot or flood lamps may be needed to provide adequate lighting for veterinary treatment. Adjustable ceiling or wall mounted fixtures will allow the light to be aimed where it is needed.

Table 4 Selection of halogen spot and flood lamps for bulk tank inspection and veterinary treatment.

* Estimates based on: fc=cd/d2, where cd=candlepower, and d=distance from lamp to work area (ft) (Frier, 1987).

Electrical code

Since dairy barns are damp and dusty environments, either type UF or nonmetallic conduit may be used for wiring. All cable or conduit should be attached to interior building surfaces and should never be concealed in the walls, ceiling, attic, or hay mow. If cable is used, it must be installed in a location where it cannot be damaged. All light fixtures must have a gasket, be fabricated of corrosion resistant materials, and be rated for wet locations (watertight).

Design example for a tie stall barn

This example illustrates the lighting system needed for the feed manger area of a 40 cow tie stall barn. The barn consists of 40 stalls of two rows with cows facing the outside wall. Each feed manger is 90 ft long and 6 ft wide (Figure 1). The example illustrates the step by step design for the feed manger alleys (Table 5) and summarizes the design parameters for all the lighting in the stall barn (Table 6).

Since the two manger alleys are the same, the design calculations will be for one row of 20 stalls. The lighting system will be designed to provide an average light level of 10 foot-candles.

The calculations shown in Table 5 indicate the following:

1. Fluorescent fixtures with two 32 watt lamps are not recommended for illumination of the manger in a stall barn at 10 fc because the fixture spacing is too large.
2. Fluorescent fixtures with one 32 watt fixture provide the best choice for 10 fc illumination of the feed manger. Provide one fixture for each 2.9 stalls. This design results in 11.2 watts per cow.
3. If incandescent fixtures are used, a single 100 watt lamp will provide the required illumination for 1.8 stalls. However, the design would result in 55 lamp watts per cow. Therefore the energy costs per cow of the incandescent system will be about 5 times that of the fluorescent system.

Figure 1. 40 head tie stall barn

Table 5 Supplemental lighting design for a 40 cow tie stall barn to provide 10 foot-candles over the manger area and 25 foot-candles over litter alley.

Table 6. Lighting design example for a 40 cow tie stall barn.

* All lamps are 4 feet long, thus replacement requires only one size.
** Determine required number of fixtures by dividing the floor area by the floor are per fixture (Tables).
*** Hang this fixture over sink area in milk room.

Summary

The best lighting system provides the required amount and quality of light at the least cost. Fluorescent or metal halide lamps that have a color rendition index of 80 or more are recommended for use in the office and milk room. In stanchion or tie-stall barns with relative low mounting heights, fluorescent lamps are the most practical. The total installation and operating costs of the system must be considered when selecting a fixture type and lamp size. Make sure that all new fixtures and wiring conform to local requirements for livestock buildings and have all new work inspected.

References

ASAE. 1993. Lighting for Dairy Farms and the Poultry Industry, ASAE EP344.2, ASAE Standards, 40th edition, St. Joseph, MI 49085-9659.

Chastain, J. P. 1994. On-Site Investigation of Indoor Lighting Systems for Dairy Facilities. ASAE Paper No. 945507, ASAE, 2950 Niles Rd., St. Joseph, MI 49085-9659.

Chastain, J. P. 1992. Lighting Requirements for the Milking Center. In: Milking Center Design (NRAES-66), Proceedings from the National Milking Center Design Conference, Nov. 17-19, pp. 214-229, Northeast Regional Agricultural Engineering Service, Ithaca, NY 14853-5701.

Frier, J. P. 1987. Principles of Lighting Design as Applied to Agriculture. ASAE Paper No. 87-3538, ASAE, 2950 Niles Rd., St. Joseph, MI 49085-9659.

MacDonald, R. and G. Henderson. 1991. Applications of Energy Efficient Lighting Systems in Livestock and Poultry Facilities. ASAE Paper No. 913545, ASAE, 2950 Niles Rd., St. Joseph, MI 49085-9659.

MWPS, 1992. Farm Buildings Wiring Handbook. MWPS-28. Midwest Plan Service, Ames, IA 50011.

NFEC, 1993. Agricultural Wiring Handbook, Chapter 13, National Food and Energy Council, 409 Vandiver West, Suite 202, Columbia, Missouri 65202.

NFPA. 1993. National Electric Code. Article 547. National Fire Protection Association. Quincy, MA 02269.

Peters, R. R. 1994. Photoperiod and Management of Dairy Cows: A Practical Review, In: Dairy Systems for the 21st Century, Proceedings of Third International Dairy Housing Conference, pp. 662-666.

Turner, L. W. and J. P. Chastain. 1995. Environmental Control in the Milking Center. In: Designing a Modern Milking Center: Parlors, Milking Systems, Management and Economics (NRAES-73). Proceedings from the Designing a Modern Milking Center National Conference, Rochester, NY, Nov. 29-Dec. 1, 1995, pp. 141-153, Northeast Regional Agricultural Engineering Service, Ithaca, NY 14853-5701.

University of Minnesota, U.S. Department of Agriculture, and Minnesota Counties Cooperating