Section III. Lighting

1. Purpose - Lighting Adequate lighting is not always a priority on dairy farms, but a well designed and maintained lighting system pays dividends in improved employee and animal performance. Although often overlooked and taken for granted, the application of electric lighting is a substantial energy input in the operation of modern dairy farms. Lighting represents 15% in Wisconsin, 24 % in New York and 16% in California of total electric energy used by a dairy farm. The cumulative magnitude of energy use by a broad range of lighting equipment in all areas of the farm complex is somehow perceived to not be as significant. The use of supplement lighting in every facet of our daily lives tends to lessen our perception of its existence and not consider the full impact on total farm energy consumption. Lighting sources include:

• Incandescent • Tungsten Halogen (Incandescent)

• Fluorescent

• Mercury Vapor

• Metal Halide

• High Pressure Sodium.

The common theme behind the use of all these sources is the basic need for supplemental light to provide people the visual acuity to perform required functions accurately, efficiently and safely. As the continuing trend toward larger dairies operating around the clock continues the necessity of efficient, well designed and maintained lighting systems becomes even more crucial to successful operation of the farm.

The available energy conservation options for improving lighting efficiency and efficacy on the farm are enormous. New and improved lighting technology is being developed continually. The choices available range from simple lamp replacements to installing new high efficiency lighting systems with programmable logic controllers and other computer based control systems.

An integral step to improving lighting on dairy farms is the performance of a specific lighting design for that area or facility. Clearly using an efficient light source in a poor design does not provide optimal lighting. This design should satisfy established criteria for light level, color rendering, efficacy, selection of fixtures suitable for the ambient environment, controls, and proper wiring and circuit protection.

A recent development in the application of lighting technology on dairy farms may involve photoperiod manipulation, or long-day lighting, of dairy cows to increase milk production. This management practice uses an increased light intensity over a defined time interval to

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stimulate increased milk production. An efficient lighting design and control system must be implemented to obtain the benefits of long-day lighting.2. Dairy Farm Task Lighting

Having a good working environment in a modern dairy is an important factor in the optimization of animal and worker efficiency, safety, and comfort. Lighting is an environmental factor that should be given careful consideration throughout a dairy facility, but it is often considered only as an afterthought during the design, construction and maintenance of a dairy facility. Various work tasks on a dairy farm require differing light considerations, as do animal feeding and resting areas.

Important factors in developing effective lighting systems include the selection of appropriate luminaires designed for the task lighting required and the room environment where the lighting equipment is installed. The very best lighting systems perform poorly in dark colored, dingy rooms.

Many areas within dairy facilities cannot be kept pristinely clean and bright, but where possible, walls and ceilings of lighted areas should be painted or covered with a bright, matte finish that is highly reflective without producing glare. This is especially important in visually intensive work areas such as milking parlors, milkrooms, cow treatment areas, and equipment repair areas. Also consider using dimmers and motion sensors on your barn lights. Quality lighting is very much a factor in improving and maintaining productivity.

There are three levels of work area or task lighting systems on dairy farms:

A. Visually intensive task lighting (generally requires highest lighting levels)

1. Milking parlors and holding areas.2. Equipment washing. 3. Equipment maintenance and repair.4. Office lighting. 5. Maternity and veterinary treatment area. 6. Utility room.

B. Lighting for livestock handling and equipment (high to moderate lighting levels)

1. Holding area lighting. 2. Feeding area lighting. 3. Animal sorting and observation. 4. General cleanup.

C. General lighting (low to moderate lighting levels.)

1. Livestock resting areas. 2. Passageway lighting. 3. General room lighting. 4. Security lighting (indoor and outdoor).

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The brightness of an object or work surface is measured in footcandles (fc). This unit of measure most likely dates back to the days when candles were used for task lighting. The level of illumination of an object or surface one foot from a candle one foot away with no other light in the room is approximately one footcandle. The level of illumination of the ground on a clear night with a full moon high in the sky is approximately one footcandle. Research was conducted in the past to determine minimum necessary light levels from many farm tasks. For example, what illumination level is needed to detect mastitis in normal milk. Table 3-1 provides recommended illumination levels for various tasks and areas on a diary farm. The rate of light output from a light source (lamp) is measured in lumens. Lamp manufacturers provide this information in their lamp catalogs and also printed on the lamp package. Table 3-2 contains light output information for typical lamps that are suitable for use on farms. Referring back to the definition of illumination in footcandles, one footcandle is equal to one lumen spread out over one square foot of surface or one lumen per square foot. To determine the amount of light (lumens) needed, multiply the desired illumination in footcandles by the area to be lighted. If all of the light output of the lamp was to get to the intended area all that would be needed would be to select the lamp type and wattage, look up the lumen output in Table 3-2 and divide into the total number of lumens needed. But all of the light from the lamp does not get to the location desired. Light goes out windows and is lost, absorbed by dark surfaces, or trapped in spaces such up in the ceiling or below the work area. Some of the light gets trapped in the fixture (luminaire) and never gets out.

Considering typical recommended practices on dairy farms, a term called coefficient of utilization is a percentage measure of the amount of light that typically gets out of the lamp and reaches the intended area to be lighted. Recommended coefficient of utilization values provided in Table 3-1 are in percent, but before they are used in the following formula they need to be entered as a decimal. For example, the coefficient of utilization for the udder area of a milking parlor is 30% but when put into the formula it is entered as 0.30. To determine the number of lamps needed to provide the minimum level of lighting for an area, first select the type of lamp to be used and the lumen output for that lamp (Table 3-2). Next determine the recommended illumination level in footcandles from Table 3-1 and the recommended coefficient of utilization for that task. Next determine the area to be lighted. Now put these values into the following formula.

Area × Footcandles desiredNumber of Lamps = --------------------------------------------------------------- Lumens per lamp × Coefficient of Utilization

Here is an example. Assume two rows of high-output T-8 fluorescent fixtures with two lamps per fixture are to be installed above the milking parlor pit. The lamps are 8 ft (96 in.) with an output of 5500 lumens. The intended purpose is to achieve 50 footcandles in the area of the cow udder lights are on 10 hours per day. Assume the put is 8 ft wide and 45 ft long. We also need to add 2 extra feet to the width because the cow udder is not over the pit. Total width of area to be lighted is 10 ft. If is harder to get light under the cow so the coefficient of utilization for the udder area will be used which from Table 3-1 is 0.30. Putting these values in the previous formula tells us we need 14 lamps. There are two

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lamps per fixture so divide by 2 to get 7 fixtures. It is probably best to put the same number of fixtures in each of the two rows, so round up to 8 fixtures with four in each row.

450 ft2 × 50fc Number of Lamps = --------------------------------- = 13.6 lamps (round up to 14 lamps) 5500 Lumens × 0.30

The wattage rating of the farm recommended lamps is also given in Table 3-2. These wattage ratings are just for the lamp. Except for incandescent lamps, there is a ballast and it generally consumes an additional 10% of energy. Therefore in the case of fluorescent, mercury, metal halide, high pressure sodium lamps, multiply the lamp wattage by 1.13 to get a good approximation of the total fixture wattage. In the case of the previous example of the 8 ft T-8 high output fluorescent lamps, each lamp is rated at 59 watts with two lamps per fixture. The total fixture wattage would be 2 times 59w times 1.13 which is equal to 133 watts. There are eight fixtures so the total for the milking parlor pit area is 1064. Just for comparison purposes, the T-8 lamp with electronic ballast is a high efficiency for the old T-12 fixtures with magnetic ballasts which have a fixture rating of 217 watts or a total for the pit area of 1736 watts. This is a savings of 648 watts or 38%. There is another side benefit. The T-8 lamps produce more light than the older T-12s. The expected life of the lamps is also given in Table 3-2. This is an average life determined by the manufacturer if the lamp is operated at the correct voltage. If an incandescent lamp is rated at 120 volts, but operated at 125 volts (this is common) lamp life is reduced by as much as 50%. To get incandescent lamps that last longer than expected, obtain ones that have a 130 volt rating. This rating is also marked on the lamp as well as the package. If a lamp rated for 130 volts is operated at 125 volts, the light output and efficiency will be slightly lower, but the life will be significantly greater. Fluorescent lamps are not made to be turned on and off frequently. They need to be used in areas where they will be turned on and operate for extended periods of time. If the fluorescent lamps are switched on and off frequently, the lamp life will be significantly reduced. Metal halide, mercury vapor, and high pressure sodium lamps produce light in an internal arc tube that is surrounded by a protective glass envelope. Mercury vapor lamps can continue to operate with the outer glass envelope broken. This can be a problem since the arc inside the lamp produces short wavelength ultraviolet radiation that can burn skin and injure eyes in a manner similar to an arc welder. This problem can be avoided by using safety mercury lamps that quit operating if the glass envelope is broken. There is a safety issue with metal halide lamps. The lamp can burst when it is operated near the end of its useful life. The arc tube inside can burst and the impact can also break the outer glass envelope. The area below will be showered with glass if the fixture is not equipped with a cover to catch the glass. If the fixture is mounted less than 12 ft above the floor, it is possible that hot particles from the bursting lamp can start a fire in flammable material. Table 3-2 only lists Type O metal halide lamps which are a type that will not burst the outer glass envelope if the arc tube should burst.

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A small amount of mercury (Hg) is required in order for a fluorescent lamp to produce light. Lamps are now manufactured with the minimum mercury practical for proper operation. The fluorescent lamps will be marked as low mercury (Hg) or sometimes have a green color to the metal end cap. When the word “deluxe” is used on a lamp it means the lamp produces extra light in the red portion of the spectrum. Red objects such as a red tractor or red barn will probably look brown at night if lighted with a clear mercury vapor lamp. The colors will look nearly natural if it is a deluxe mercury vapor lamp. Colors will only look their natural color if the receive a fairly even distribution of all of the colors of the spectrum. Incandescent lamps produce all of the colors of the spectrum and somewhat heavy on the red end and minimal on the blue end. The other types of lamps produce most of their light at a limited number of specific wavelengths.

The clear mercury vapor lamp does not produce any red light which makes red objects look brown. A designation called color rendering index (CRI) is given for the lamps in Table 3-2. The CRI allows for a comparison between different lamps in describing who well colors will look natural under the lamps. The higher the CRI the better job the lamp will do at making objects of various colors look normal. Another color indicator for lamps is the color temperature which is also given in Table 3-2. Color temperature is in degrees Kelvin. The color temperature of 3400 will make red, orange, and yellow objects appear more natural. The color temperature of 4100 will make violet, blue, and green objects appear more natural. A color temperature of 5000 is comparable to light from the sun at noon on a cloudless day. The higher the color temperature the more natural blue and violet objects will look and the lower the color temperature the better red objects will look. The common measure of efficiency of lamps is the light output divided by the power use in watts or lumens per watt. Incandescent lamps have a very low efficiency rating, usually 20 lumens per watt or less. The 4 ft and 8 ft T-8 fluorescent lamps with electronic ballasts typically will have an efficiency in the range of 80 to 100 lumens per watt. For the T-12 fluorescent lamps with magnetic ballasts the efficiency is more in the range of 60 to 80 lumens per watt. Compact fluorescent lamps that are used to replace incandescent screw-in lamps typically have an efficiency of 40 to 65 lumens per watt. They generally replace incandescent lamps with an efficiency in the range of 12 to 17 lumens per watt. Typical mercury vapor lamps used on farms have an efficiency of 45 to 65 lumens per watt. For outside area lighting it is more common to use high pressure sodium even though is tends to produce extra yellow light because the efficiency is in the range of 90 to 130 lumens per watt. The typical recommendation is to replace a mercury vapor lamp with a high pressure sodium lamp of half the wattage to get the same light output.

The T-8 fluorescent lamps with electronic ballasts have an additional advantage over the older T-12 fluorescent lamps with magnetic ballasts in that if installed in closed fixtures, they will operate fairly efficiently at temperatures down to zero. In the past fluorescent lamps did not operate well when the temperature dropped below 50 degrees. Even the higher wattage compact screw-in fluorescent lamps generally work well in animal housing with exposed lamps.

All the lamps listed in Table 3-2 (except incandescent and halogen) use a ballast. This ballast consumes energy. To estimate the power consumed by a fixture with a ballast, multiply the lamp wattage by 1.13. The column of Table 3-2 that gives fixture efficacy does

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include the energy consumed by the ballast and the values are for the actual fixture not just the lamp.

Table 3-1. Suggested Dairy Facility Illumination Levels

Work AreaRecommend Illumination

Level fc1

CoefficientUtilization

Estimate %2

Lamp(s)Output

lm/sq ft 3

Milking Center Parlor, general lighting Operator pit (cows udder) Cow return alleys Cow holding area

20 fc 50 fc 20 fc 10 fc

35 30 35 35

57 167 57 29

Milk Room General lighting Equipment washing area Bulk tank/silo interior

20 fc 100 fc 100 fc

35 40 80

57 250 125

Utility/Equipment Room General lighting Equipment repair and maintenance

20 fc 100 fc

30 45

67 220

Maternity/Treatment areas General lighting Treatment or surgery

20 fc 100 fc

30 50

67 200

Cattle confinement areas (indoor) 20 fc 30 67

Cattle confinement areas (outdoor) 1 fc 20 3.3

Feed Storage areas Grain bin areas Commodity buildings

5 fc 10 fc

20 25

25 40

1. Source: ASAE Lighting Systems for Agriculture Facilities 2. Coefficient of utilization given for luminaries direct at least 65 percent of light down 3. Lamp output needed to meet recommended lighting level, lumens/sq ft

3. Selecting Luminaires

Choosing appropriate luminaires and lamps for a specific lighting task requires an understanding of the relative performance, efficiencies and color rendition of various light types. Table 3-2 provides representative information about costs and lamps commonly used in dairy facilities. Allowances for fixtures, installation and maintenance costs need to be taken into consideration as well.

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Table 3-2. Lamp types and selection data

Lamp TypeWatts Mean

Lumens

Avg.Life

Hr

FixtureEfficacy

Lm/W

ColorTemp.

oK

Color

Rendering

Index

(CRI)

Cost

Per

Lamp

$

Incandescent 75 1,190 750 16 ------ 100 0.56

Incandescent 100 1,710 750 17 ------ 100 0.56

Incandescent 150 2,650 750 18 ------ 100 2.08

Incandescent - Halogen 100 1,650 1,500 16 ------ 100 8.41

Incandescent - Halogen 300 5,950 2,000 20 ------ 100 6.89

Incandescent - Halogen 500 10,550 2,000 21 ------ 100 8.85

Fluorescent, Compact 10 416 8,000 37 4,100 82 4.99

Fluorescent, Compact 15 760 8,000 44 2,700 82 4.99

Fluorescent, Compact 26 1,360 8,000 46 4,100 82 5.99

Fluorescent, T8, 48 in. Low Hg 32 2,660 20,000 73 3,500 78 2.00

Fluorescent, T8, 48 in. Low Hg 32 2,660 20,000 73 4,100 78 1.98

Fluorescent, T8, 48 in. Low Hg 32 2,610 20,000 72 5,000 86 5.32

Fluorescent, T12, 48 in. 34 2,280 20,000 59 4,100 60 1.55

Fluorescent, T12, 96 in. 60 5,060 12,000 74 4,100 60 4.89

Fluorescent, T12, 96 in, HO 96 6,960 12,000 64 4,100 60 6.34

Fluorescent, T8, 96 in. HO 59 5,500 15,000 90 3,500 78 9.58

Fluorescent, T8, 96 in. HO 59 5,500 15,000 90 4,100 78 8.92

Fluorescent, T5, 45 in. Low Hg 28 2,726 30,000 86 4,100 85 13.17

Fluorescent, T5, 45 in. Low Hg 54 4,700 30,000 77 4,100 85 15.21

High Pressure Sodium 70 6,400 24,000 81 1,900 22 23.39

High Pressure Sodium 150 16,000 24,000 95 2,000 22 22.65

High Pressure Sodium 250 28,000 24,000 99 2,100 22 22.78

High Pressure Sodium 400 51,000 24,000 112 2,100 22 22.06

Metal Halide, Type O 70 3,500 12,000 44 3,200 70 48.35

Metal Halide, Type O 150 10,200 10,000 60 4,000 65 57.80

Metal Halide, Type O 250 17,000 10,000 60 4,000 65 55.55

Metal Halide, Type O 400 26,000 20,000 57 3,800 65 53.30

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Mercury Vapor, Deluxe 150 6,800 24,000 40 3,900 50 22.55

Mercury Vapor, Deluxe 250 8,400 24,000 30 3,900 50 29.25

Mercury Vapor, Deluxe 400 14,400 24,000 32 3,900 50 27.70

Visually-Intensive Task Lighting

Milking

The milking operation on a dairy farm is a critical, repetitive task that requires excellent visual observations of equipment operations, udder prepping, udder health and cleanliness, and post-milking teat treatment. Inadequate lighting can accelerate fatigue and greatly diminish the performance of the milking staff. Poor milker performance leads quickly to herd health problems and significant drops in milk production. In the milking parlor, lighting levels in the pit area and near the cow’s udder (the work plane) should be 50 footcandles (fc) or more, as recommended by the Illuminating Engineering Society (IES) and the American Society of Agricultural Engineers (ASAE). See Table 3-3.

Moisture resistant fluorescent or metal halide luminaires provide the most effective and comfortable lighting. See Table 3-3. If the ceiling is 12 feet or less above the pit, fluorescent luminaires are generally more effective. If the ceiling is higher, metal halide luminaires are very effective. Luminaire layout will vary depending on the parlor design. If fluorescent luminaires are used, generally two rows of continuous (end to end) double tube luminaires mounted over the outer edges of the pit will provide uniform lighting with little or no shadows. See Figure 3-1.

If metal halide luminaires, a single row of luminaires over the center of the pit will work nicely, assuming there is adequate mounting height (12 feet or more). Luminaire spacing is dependent on the wattage and luminaire design selected. See Figure 3-2.

Parlor Stalls and Holding Area

It is important to have reasonably good, uniform levels of illumination in the holding area, parlor stall area, and the cow return lane areas in the milking center. The IES and ASAE

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Figure 3-2. Example of metal halide milking parlor pit lighting

Figure 3-1. Example of high output fluorescent milking parlor pit lighting

recommend a uniform lighting level of 20 fc in the parlor stall area and return lanes. It is recommended that the holding area have a uniform 10 fc illumination level. If the holding area is illuminated at a lower level than the parlor cow traffic area, it will facilitate cow traffic flow. Cows are more comfortable traveling from areas of lower illumination toward areas of higher illumination. See Figure 3-3. If it is important to have color rendition like the parlor pit area, then it would be prudent to use fluorescent or metal halide lighting in the cow traffic areas.

If color rendition is not deemed critical in the cow traffic areas, high-pressure sodium (HPS) luminaires are a good choice. They offer a higher level of lighting efficiency, and are often less expensive to install and maintain. Cow return lanes can often be effectively lighted with “wall pack” luminaires, which are rectangular lighting fixtures that are mounted, at proper spacing, high up on the sidewalls. The lenses on these fixtures aim the light onto the traffic areas. Consider adjusting lights in the dairy barn to increase milk production.

Table 3-3. Milking parlor pit, stall, return lanes and holding area lighting

Milking Parlor Pit 50 fc Fluorescent, 2 lamp, moisture resistant at udder Metal Halide, moisture resistant

Parlor General Lighting Stalls and Return Lanes

20 fc Fluorescent, moisture resistant Metal Halide, moisture resistant High pressure sodium, moisture resistant

Holding Area 10 fc High pressure sodium, moisture resistant Metal Halide, moisture resistant Fluorescent, moisture resistant

Equipment Washing

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Figure 3-3. Lighting in parlor stalls, return lane lighting, and holding area lighting

Milking center equipment washing areas, such as the wash sink in the milkroom, require high levels of illumination. Inspecting equipment for proper cleanliness is important in maintaining low bacteria count and high quality milk. The IES and ASAE recommend lighting levels of 75 – 100 fc in equipment cleaning areas. See Table 3-4. Since much of the milking system is now cleaned in place, this recommendation only applies to those areas where equipment is disassembled and manually cleaned. Generally, fluorescent, moisture resistant luminaires are appropriate to illuminate equipment wash areas. Luminaires should be mounted above work areas to provide shadow-free light at the work surface. See Figure 3-4.

The interiors of bulk tanks or milk storage silos need to be visually inspected for cleanliness. This is best accomplished with a portable moisture resistant luminaire. For some situations a fluorescent wand-type may be appropriate. The luminaire should have a protective sleeve over the lamp to contain any glass pieces, should the lamp break. It is recommended that 100 fc be provided for inspection of the interior or bulk tanks and silos. General lighting in the milkroom should provide a uniform 20 fc illumination level. Like the equipment washing area, fluorescent luminaires are most common. However, if ceilings are high (12 feet or more), metal halide luminaires work well.

Table 3-4. Milkroom and equipment wash area lighting

Task area Illumination Recommended

Requirement Luminaire

MilkroomGeneral Lighting

20 fc Fluorescent, 2 lamp, moisture resistantMetal Halide, moisture resistant

Equipment washing(Wash sink area)

100 fc Fluorescent, 2 lamp, moisture resistantMetal Halide, moisture resistant

Bulk Tank/Silo InteriorCleaning and inspection

100 fc Fluorescent portable wand light, insulated and moisture resistant

Office Lighting

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Figure 3-4. Milkroom lighting

Most milking centers include the farm office space. Proper, glare-free lighting is essential in an office to facilitate the daily activities of record keeping, computer operations, and general office work. Farm office general illumination levels should be at least 50 fc with specific task lighting on the desk surface of 100 fc or more. See Table 3-5. Once again, fluorescent lighting is most suitable to provide glare-free lighting with few shadows.

Table 3-5. Dairy office lighting

Task Area Illumination Requirement Recommended LuminaireGeneral Office lighting 50 fc Fluorescent with prismatic lens

Reading, writing, keyboard 50 fc Fluorescent with prismatic lens

Maternity and Veterinary Treatment Area

The maternity and veterinary treatment area in a dairy facility requires general lighting levels of 20 fc to facilitate observations of sick cattle and cows ready to calve. Intense visual and often delicate tasks such as operating procedures or other animal treatment require minimum lighting levels of 100 fc. See Table 3-6. Fluorescent or metal halide luminaires are most appropriate for these areas. For surgery, portable halogen spotlights may be required to provide adequate task lighting. In the treatment/operating area, the luminaires need to be more concentrated and arranged to minimize any shadows.

Table 3-6: Maternity and treatment area lighting (indoors)

Task Area Required Illumination

Recommended Luminaire

Maternity/treatment area (general lighting)

20 fc Fluorescent or Metal Halide moisture resistant

Veterinary Treatment and Surgery area

100 fc Fluorescent or Metal Halide moisture resistantPortable halogen spot lights for lighting surgical area

Utility Room Lighting

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The utility room in a modern milking center houses most of the key operating systems that makes the milking parlor/milkroom area function. Vacuum pumps, refrigeration compressors, condensers, air compressors, electrical distribution panels, and, often, the standby power system are all found in the utility room. It is recommended that a uniform general illumination level of 20 fc be provided in the utility room. See Table 3-7. Portable task lighting is also required to raise local illumination levels to 100 fc when maintenance and repair is conducted on individual pieces of equipment. General lighting is commonly provided by fluorescent luminaires. If ceilings are 12 feet or more in height, metal halide luminaires will also provide excellent, uniform lighting.

Table 3-7. Utility room lighting

Task Area Illumination Requirement Recommended LuminaireGeneral lighting 20 fc Fluorescent with prismatic lens

Metal Halide, low bay

Equipment Maintenance and repair

100 fc Portable incandescent or halogen trouble light

Livestock Handling Lighting

Lighting for Dairy Cattle Confinement Structures

General lighting systems for dairy cattle confinement structures, whether freestall barns or simple loafing shelters, should provide 10 fc of light. See Table 3-8. This is important for the performance of general work tasks such as separating cattle, observing cattle for illness or heat detection, and performing general maintenance and cleanup operations. This lighting level is also necessary to provide safe operator movement throughout the facility. High pressure sodium luminaires provide the most effective and efficient illumination for this

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Figure 3-5. Fluorescent lighting in a utility room

lighting need. If good color rendition is desired, metal halide luminaires are commonly used. See Figure 3-6. If the structure has a very low ceiling (less than 12 feet), fluorescent luminaires may be more appropriate. If ambient temperatures are likely to dip below 50° F., the fluorescent fixtures should have high output ballasts and lamps to reduce cold temperature light degradation.

Illumination levels in feeding areas within confinement structures should be 20 fc. This facilitates the operation of feeding wagons or trucks and encourages cows to move to the feeding area and eat. A heavier concentration of the same type of fixtures used for general lighting can be used to provide the higher illumination level.

Long-day Lighting

Numerous university studies suggest that supplemental lighting that provides lactating dairy cows with a uniform light level of 15 to 20 footcandles for 16 to 18 hours per day will increase milk production. Generally, in freestall resting barns, long day lighting systems

utilize high-pressure sodium or metal halide light fixtures. These high efficiency fixtures

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Figure 3-6. Example of metal halide lighting in a dairy cattle confinement feeding barn

Figure 3-7. Freestall resting barn with supplemental long day lighting

provide sufficient lighting while using less energy than other fixture types. To gain the full benefit of this supplemental lighting, the dairy cows must have a 6 to 8 hour dark period every 24 hours. When herds are on 3x milking schedules, it is often difficult to achieve the required dark period. When considering a long day lighting system, it is important to note that 2 to 3 times as many light fixtures are required compared to conventional freestall barn lighting recommendations. See Figure 3-7. Open Corral Confinement Systems

Open corral confinement systems present a special lighting challenge. It is difficult to provide effective, uniform lighting in large open areas. A low level (less than 1 fc) of general lighting can be achieved by locating high pressure sodium HID luminaires around the perimeter of the corral. The luminaires would have to be weather-proof with wide beam angle reflectors to aim the light over a broad area of the corral. See Figure 3-8. Lighting at feeding areas in corrals should be 3 fc. Again, this facilitates nighttime feeding operations and encourages animal movement to the feeding area. Corral lighting can best be accomplished by mounting luminaires on very tall poles, which would allow luminaire mounting heights of at least 40 to 50 feet. Taller poles allow wider beam spread and the use of higher wattage, more efficient luminaires, thus reducing the total energy requirement for the lighting task.

Table 3-8. Cattle Confinement and Feeding Area LightingTask Area Required llumination Recommended Luminaire

Confinement Structures (General Lighting)

10 fc High pressure sodium, Metal halide Fluorescent (All moisture resistant)

Feeding areas (in confinement buildings)

20 fc High pressure sodium Metal halide Fluorescent (All moisture resistant)

Corrals (general lighting)

0.25 fc High pressure sodium (weatherproof with wide beam angle reflectors) on tall poles

Corral Feeding areas 3 fc High pressure sodium, (weatherproof with wide beam angle reflectors) on tall poles.

Special Pens and Chutes General (outdoors) 10 fc High pressure sodium

Sick Animal Treatment (outdoors)

50 fc High pressure sodium (provided from several directions to reduce shadows)

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Figure 3-8. Example of 1,000 W floodlight for feeding corral lighting

General Lighting

Feed Storage and Processing Areas

Feed storage areas such as commodity storage buildings and grain bins generally require less light than other areas because little work is done within the storage areas. Table 3-9 provides recommended light levels for these areas. Grain bins should have 2 – 5 fc of light around them to facilitate safe walking and equipment operations around them at night.Commodity storage buildings should have up to 10 fc of light in front of and within the storage facility to facilitate commodity removal and mixing operations at night. High pressure sodium luminaires will provide the most efficient light source for these areas. See Figure 3-9. These lighting systems can be set up on dusk to dawn timers or photoelectric controls, since they are only needed for nighttime operations.

Table 3-9. Feed and grain storage area lighting

Task Area Required Illumination Recommended LuminaireGrain Bin area 2-5 fc High pressure sodium, weather-proof,

with dusk to dawn control

Commodity Storage 10 fc High pressure sodium, weather-proof with dusk to dawn control

4. Lighting Energy Utilization Indices (EUIs) The largest portion of all electrical energy used for lighting on the dairy farm occurs within the milking center and mainly in the milking parlor. Maintenance of acceptable lighting levels in this area is crucial to providing operators visual acuity to perform their tasks. The energy use to provide lighting on a dairy farm is driven by a number of factors. These include:

• Illumination levels required • Proper design, selection, placement and installation of lighting system • Duration of time period lighting is used • Energy efficiency (lumens per watt) of lighting system selected • Maintenance of lighting system.

The kilowatt-hours used per cow-year for operating all lighting equipment on the dairy establish the EUI for lighting. A reasonable range for lighting EUI’s on California dairies would be from 30 to 75 kWh per cow-year.

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Figure 3-9. High pressure sodium fixture in commodity storage shed

The advent of photoperiod manipulation or long day lighting (LDL) to increase milk production can significantly increase the EUI for lighting. Dairies utilizing LDL technology in their freestall barns would be expected to have lighting EUI’s range from 100 to 175 kWh per cow-year. Although lighting EUI’s will increase appreciably on those dairies adopting LDL, relatively modest increases in milk production make the supplementary lighting very cost-effective.

5. Lighting Energy Conservation Measures (ECMs) The most effective energy conservation measure for dairy lighting systems is to replace inefficient luminaires with higher efficiency types. For example, if lighting for outdoor corrals and feeding areas is provided by incandescent or halogen flood lights, converting to high pressure sodium lighting at the same lighting level would save a significant amount of energy. High-pressure sodium lamps produce 5 to 6 times more lumens/watt of energy used compared to incandescent or halogen lamps. Table 10 below illustrates energy conservation measures for lighting and the percentage savings each measure will provide.

Table 3-10. Lighting Energy Conservation Measures and Savings

Lighting Type Energy Conservation Measure % Energy SavingsIncandescent Convert to halogen lamps 20-38%

Incandescent Convert to compact fluorescent, if appropriate 75%

Incandescent Convert to fluorescent tube luminaires 80-85%

Fluorescent T-12 Magnetic ballasts

Convert to fluorescent T-8 with energy efficient ballasts

25%

Mercury vapor Convert to Metal Halide, if appropriate 43-54%

Mercury Vapor Convert to High Pressure Sodium, if appropriate 44-59%

Converting to higher efficiency luminaires may not always be cost effective. Buying and installing new higher efficiency luminaires may cost more than is saved in energy costs. For example, it may not pay to replace existing fluorescent T-12 luminaires with new T-8 luminaires with high efficiency ballasts. However, it would pay to convert the existing ballasts and lamps from T-12 to T-8 while keeping the existing fixture.

The most important point to make about lighting energy conservation is to install the most appropriate, most efficient luminaire for the task. Purchasing high quality, energy efficient luminaires generally results in better lighting with continued energy savings over the life of the luminaire.

Compact fluorescent lights use one-quarter of the energy of that incandescent lights use, and they produce less heat, and last six to ten times longer. For lights in daily use, switching to compact fluorescents will typically pay back in one to two years.

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In an incandescent lamp, an electric current heats up a metal filament in the bulb, making it glow white-hot and give off light. The problem is that only 10% of the electricity is used to make light - the rest ends up as heat.

Compact fluorescent bulbs are much more efficient at turning electricity into light. A typical compact fluorescent is a one-piece light that holds both the fluorescent tube and the electronic ballast that controls the electric current. They are designed to screw easily into a standard incandescent fixture without modification. They can be used outdoors as long as they are protected from the weather, so they are suitable for use in barns and storage sheds.

In very cold weather there is a slight delay before they reach full brightness.

Compact fluorescent lights are more expensive (about $5 to $7) than standard incandescent lights, but if they are in use for more than six hours a day, they will pay for themselves usually within two years. Since they last eight to ten times longer, there is a further savings in the labor needed to replace the lights.

Use this rule of thumb: If you use 60, 75, or 100-watt incandescent bulbs daily for four hours or more, replace them with 17, 20, or 23-watt compact fluorescents.

If the fluorescent tubes in your barns and work areas are more than 12 years old, there’s a good chance that they’re due for an upgrade to modern T8 fluorescent lamps. T8 lamps are the highest efficiency lamps for 4 and 8-foot fixtures, and can provide the same amount of illumination using 20 to 40 percent fewer watts. An electronic ballast with the T8 lamp saves an additional 7 to 10 percent.

Larger incandescent fixtures, such as pole lights or floodlights should be replaced with more efficient lights such as sodium or metal halide lamps. These are designed specifically to cast a big pool of light over a wide area but with significantly less energy consumption. These lights, which require unique fixtures, are typically seen in streetlights, modern warehouses, and large stores.

The environmental benefits of making the change are considerable. Replacing a 75-watt incandescent light with a 20-watt compact fluorescent saves about 550 KwH over its lifetime. If the electricity comes from a coal fired generating plant, the savings represents about 1300 pounds of carbon dioxide and 20 pounds of sulfur dioxide that would have otherwise been released into the atmosphere.

Operator Level Checks - Lighting

In a dairy farm environment, even the best lighting systems lose their effectiveness quite rapidly if not properly maintained. There are many factors that influence the coefficient of utilization. Dust and dirt accumulation on lamps and luminaire refractors will significantly reduce the effective light output of the fixture. This is known as luminaire dirt depreciation (LDD). Luminaires in very dirty locations should be cleaned monthly. Luminaires in less dirty environments should be thoroughly cleaned at least twice per year.

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Since light reflectance of ceilings and walls is an important factor in lighting system performance, it is important to keep reflective surfaces clean. As dirt accumulates on these surfaces, they will absorb light rather than reflect it, thus reducing the quality of light in the task area. This is known as room surface dirt depreciation (RSDD). In lighted dairy facilities, it is important to keep walls and ceilings cleaned. They should be painted or covered with bright white or other reflective colors.

The light output for all common lamps diminishes over the life of the lamp. This loss of light output over time is known as lamp lumen depreciation (LLD). For example, a typical incandescent lamp will produce 89% of its initial lumen output at 70% of its normal life. A metal halide lamp may only produce 60% or less of its initial lumen output at 70% of its life. To maintain proper light levels, it is appropriate to replace lamps before they burn out. Some will say that a HID lamp will never burn out. This is not true but the light output will be a fraction of the original lumen output. While a depreciated lamp will still “work”, less light will be received and the energy consumed remains nearly unchanged. As lighting system output diminishes due to dirt depreciation factors and lamp lumen depreciation factors, it may be difficult to sense the light loss with the naked eye. This is because the light loss is gradual, and the operator tends to get used to diminished levels until the light levels are far too low. To monitor lighting system performance, use a light meter to measure footcandle levels in each lighted area when the system is new. Then check footcandle levels in the same areas on a monthly basis to determine diminished system performance. The light meter readings will indicate when cleaning and relamping should occur. Best to make these measurements at night when ambient light will not interfere with the readings.

6. Summary

Energy efficient lighting requires only about one third the energy of standard incandescent lighting. It represents the most cost-effective energy efficiency opportunity available to the commercial sector. Converting to energy efficient lighting can reduce a company’s energy expenses for lighting by up to 70%, depending on the lighting technologies and practices being replaced. The return on investment for lighting retrofits is typically greater than 30% with a simple payback within three years.

Whether retrofitting, remodeling, or constructing a new building, good lighting design is the key to minimizing energy costs for lighting. Besides incorporating efficient technology, effective lighting design considers the illumination needs based on different uses of floor space, incorporates natural lighting, and provides workspace occupants flexibility in controlling light levels.

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Compact Fluorescent Lamps (CFL)

Conventional incandescent lamps are the least efficient lighting option. They convert only about 10% of the energy into light while transforming the rest into heat. Commercially available energy efficient lighting technologies include daylighting, fluorescent lamps, and high intensity discharge lamps. Solid-state lighting is a promising advanced technology under development. These technologies are discussed below.

The use of natural light for illuminating interior space is referred to as daylighting. When properly designed and effectively integrated with a building’s electric lighting system, sunlight can offer significant energy savings benefits over traditional incandescent or flourecsent lighting. The building’s air conditioning requirements are also reduced because less heat is generated by electric lights. Besides window design, daylighting options include advanced skylights, clerestories, reflectant surfaces, light shelves, and light pipes.Conventional fluorescent lamps with magnetic ballasts consume about one-third the energy required for incandescent lamps. Energy efficient fluorescent lamps combine smaller diameter fluorescent bulbs with electronic ballasts. They require only about two-thirds of the energy required for conventional fluorescent lamps.

Small-diameter fluorescent lamps folded for compactness are called compact fluorescent lamps (CFLs). They last up to 10 times longer than incandescent lamps, and they use about one-fourth the energy, producing 90% less heat. Even smaller fluorescent lamps, sub-compact fluorescents, are designed to replace incandescent lamps in standard fixtures. Recessed can fluorescents are compact fluorescent lamps in air-tight recessed cans designe to replac incandescent recessed can lighting.

DOE is currently aggregating volume purchases of sub-compact fluorescents and recessed can flourescents by commercial entities in order to encourage production volumes necessary for them to become market competitive. Interested companies can refer to http://www.eren.doe.gov/buildings/emergingtech/pdfs/lightbulbs.pdf for sub-compacts and http://www.pnl.gov/cfldownlights/index.html for recessed cans.

The compact fluorescent torchiere lamps are recommended as an energy efficient alternative for halogen torchiere lamps (floor lamps). The energy-efficient torchiere gives off approximately 50% more light while consuming only one quarter the energy of a halogen torchiere. Compact Fluorescent torchiere lamps are also much safer than halogen torchieres because halogen torchieres have a bulb temperature of 1000 °F compared to 100 °F for compact fluorescent torchiere lamps.

The high intensity discharge (HID) lamps are a very compact light source. A single 100-watt HID lamp, for example, provides as much light as a 500-watt incandescent lamp or a 160-watt, four-lamp fluorescent fixture. The HID lamp, however, is approximately the size of a common 100-watt incandescent bulb. HID lamps are typically used when high levels of light are required over large areas and when energy efficiency and/or long life are desired. These areas include gymnasiums, large public areas, warehouses, outdoor activity areas, roadways, parking lots, and pathways. More recently, however, HID sources, especially metal halide, have been used in small retail and residential environments.

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The U.S. DOE is currently sponsoring the development of solid-state lighting for general illumination. Unlike incandescent and fluorescent lamps, solid-state lighting creates light without producing heat. A semi-conducting material converts electricity directly into light, which makes the light very energy efficient. Solid-state lighting is currently used commercially for some applications but requires further development to be suitable for general illumination.

Shapes and Configurations

The shape of the CFL and the reflector in the fixture dictates how light will be distributed in a space and the size and shape of the fixture. If directional lighting is required, it is important to select a CFL and reflector combination that fulfills this requirement. Non-reflector type fixtures can be used if a more diffuse lighting pattern is required like floor or table lamps.

The three basic configurations for CFLs include:

* Self-ballasted CFLs are typically screw-in type CFLs and contain the ballast and lamp as one integral unit.

* A modular CFL has two pieces, a lamp and ballast. Each piece can be replaced separately.

* A dedicated CFL would be a lamp only, designed to fit into a hardwired fixture that contains the ballast.

Both dedicated and modular ballasts have a service life around 40,000-60,000 hours. This is greater than the life of the lamp (10,000 hours), so when the cheaper lamp component burns out it can be replaced while retaining the ballast.

Ballasts and Start-up

Ballasts are used to control the CFL's current and provide startup voltage. Ballasts can be magnetic or solid-state electronic.

Magnetic ballasts are typically less efficient, noisier, and heavier than electronic ballasts. Recently, costs of electronic ballasts have dramatically decreased making them comparable to magnetic ballasts.

Electronic ballasts do have one drawback: unlike magnetic ballasts, which operate at line frequency (60 Hz), electronic ballasts operate at the 20 to 60 kHz frequencies and can introduce harmonic distortion or noise into the electric line, potentially overheating neutral lines, transformers, and motors.

This is normally not a problem, except for facilities with heavy lighting loads and a large number of electronic ballasts.

Another important aspect of a CFL's ballast is the starting method. The goal of the starter is to ionize the gas to allow an electrical arc between electrodes and begin illumination.

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Types of starting methods include:

* Preheat lamp starters heat the electrodes to start, essentially using them as filaments, boil off electrons and ionize the gas to begin the illumination process. There can be significant delay before the lamp begins to illuminate.

* Rapid start ballasts heat the electrodes quickly and then apply a 200-300 volt starting voltage to create the arc and begin the illumination process. Although not as slow as preheat starting, there is a slight delay of one second or less with rapid start ballasts.

* Instant start ballasts allow the CFL to start without delay by applying a high initial voltage greater than 400 volts -- instantly creating an arc across the electrodes. Instant start ballasts have the lowest power losses but can decrease the life of the lamp because of degradation of the emissive coating on the electrodes from the high starting voltage. Instant start ballasts are good for applications with less frequent on/off switching.

Bases and Sockets

The base is the part of the CFL that plugs into an electrical socket. Bases for CFLs come in three types: screw-in, 2-pin, and 4-pin.

* The screw-in base is the same as those used for incandescent bulbs. These are the best when replacing an existing incandescent bulb.

* Two-pin bases are used on CFLs with preheat starting. Each two-pin lamp has an internal preheat starter. Four-pin bases are used on CFLs with rapid or instant start.

* With a four-pin base, the starter is contained in the ballast and not in the lamp like the two-pin. Four-pin bases are also required for dimming applications.

An additional benefit of the two- and four-pin socket is that it is not possible for someone to replace the CFLs with incandescent bulbs.

Dimming

Dedicated dimming ballasts are available for CFLs greater than 26 watts with four-pin bases and electronic ballasts. Dimming ballasts are capable of modulating the light output from 1-100 percent. Dimming ballasts are expensive and can cost $175 to $225 per fixture, not including the required controls. This high initial cost in conjunction with low watts makes dimming control of compact fluorescents an unreasonable energy savings measure.

There are also screw-in, self-ballasted CFLs specifically designed to work with existing incandescent dimming circuits. Normal screw-in CFLs should not be used on incandescent dimming circuits.

Making the best choice

When selecting CFLs, it is important to understand the requirements of your application beyond just the energy savings. Inexpensive incandescent lights may be better suited in areas where lights are used infrequently like closets or utility rooms. In addition, incandescent bulbs may be better suited for applications with extreme cold conditions

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because they are not sensitive to temperatures like typical CFLs. However, there are CFLs designed specifically to handle these extreme conditions at an additional cost.

It’s also important to be aware of the color rendering requirements of the application. The two color metrics commonly used in lighting are the correlated color temperature (CCT) and the color rendering index (CRI):

* The correlated color temperature (CCT) is a measure of the warmth of a lamp's appearance measured in Kelvins (K). Select higher ratings (>3,500K) when looking for a cool quality to the light and lower ratings (<3,500K) when looking for a warmer appearance. CFL lamps can be found in the 2,700-6,000K range compared to 2,700-3,000K for incandescent bulbs.

* The color rendering index (CRI) is used to quantify the color quality of a light source. The more accurately a source renders a sample of standard colors relative to a reference source, the greater the CRI. CRI is measured on a scale of 0-100. Typical incandescent bulbs have a CRI around 95, while most CFLs are 82-88. This is the reason why many retail applications still use incandescent bulbs for display cases and product merchandising.

Benefits

Advanced lighting technologies like fluorescent and high intensity discharge lamps are several times more energy efficient that traditional incandescent lights. The return on investment of replacing incandescent bulbs with fluorescent ones is often greater than 30%. In addition, the use of daylighting can provide full spectrum, natural light without the use of any electricity. These efficient lighting alternatives last 5 to 13 times longer than traditional incandescent lights, reducing inconvenience and maintenance costs. Also, studies indicate increased worker productivity from well designed lighting.

Energy Savings

Table 3-11 shows the energy savings per year of a compact fluorescent light bulb compared to an incandescent bulb producing an equivalent amount of light.

Table 3-11. Annual energy savings due to replacing an incandescent bulb with a compact fluorescent bulb

(Assumes that the bulb is used for 4000 hours/year and electricity costs 10¢/kWh)

Incandescent(watts)

Fluorescent(watts)

Kilowatt-hours saved/year

Financial Savings/year

60 15 180 $18

75 20 220 $22

100 25 300 $30

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Emissions

Lighting is responsible for 450 million tons of U.S. CO2 emissions per year. Because of their advantages over traditional incandescent bulbs, advanced lighting technologies can potentially make a significant dent in the US’s CO2 emissions. Replacing a 75-watt incandescent light with a 20-watt compact fluorescent saves about 550 KwH over its lifetime. If the electricity comes from a coal fired generating plant, the savings represents about 1300 pounds of carbon dioxide and 20 pounds of of acid-rain causing sulfur dioxide that would have otherwise been released into the atmosphere.7. Glossary of Lighting Terms

Ballast : A device used with an electric-discharge lamp to obtain the necessary conditions (voltage, current and waveform) for starting and operating the lamp.

Ceiling Cavity Ratio (CCR): A number indicating ceiling cavity proportions calculated from length, width and height.

Coefficient of Utilization: The ratio [percent] of the lumens emitted from the luminaire(s) to the lumens received on the work plane.

Color Rendering Index (of a light source) (CRI): A measure of the degree of color shift objects undergo when illuminated by the light source as compared with those same objects when illuminated by a reference source of comparable color temperature. The higher the CRI, the more “natural” colors appear when illuminated by the light source.

Diffuser: A device to redirect the illumination of a lamp.

Footcandle: A measure of the level of illumination on a surface. One footcandle is light intensity produced by one lumen of light per square foot.

General lighting: Lighting designed to provide a uniform level of illumination throughout the area involved exclusive of any provision for special localized lighting requirements.

Glare: The effect of brightness or brightness differences within the visual field sufficiently high to cause annoyance, discomfort, or loss in visual performance.

High-bay Lighting: Interior lighting where the roof truss or ceiling is more than 25 ft. above the floor.

High Intensity Discharge (HID) Lamp: An electric-discharge lamp using a temperature stabilized light producing arc. Common HID lamps include mercury vapor, metal halide and high pressure sodium.

High Pressure Sodium (HPS) Lamp: A high intensity discharge (HID) lamp in which light is produced by radiation from sodium vapor operating under partial pressure.

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Incandescent Filament Lamp: A lamp in which light is produced by a filament heated by an electric current.

Lens: A glass or plastic element used in luminaries to change the direction and control the distribution of light rays.

Light : Radiant energy that is capable of exciting the retina and creating a visual sensation.

Light Loss factor (Maintenance Factor): A ratio comparing the amount of light on the task surface provided by a lamp to the value if the lamp operated at its initial (rated) lumen output and if no appreciable variation or depreciation had occurred.

Localized General Lighting: Lighting utilizing luminaires above the visual task and contributing also to the illumination of the surrounding area.

Low-bay Lighting : Interior lighting where the roof truss or ceiling height is 25 ft or less above the floor.

Lumen: A unit of measure of the quantity of light emitted from a lamp. One lumen impinging on an area one foot square will produce a light intensity of one footcandle.

Luminaire: (light fixture) A complete lighting unit consisting of a lamp (or lamps), ballasting (when applicable), together with the parts designed to distribute the light, to position and protect the lamps and to connect the lamps to the power supply.

Luminous Efficacy of a Source of Light (Luminous Efficiency): The total radiant power emitted by a lamp divided by the total lamp power (watts) input. It is expressed in lumens per watt.

Mercury Vapor Lamp: A high intensity discharge (HID) lamp in which the major portion of the light is produced by radiation from mercury operating at a partial pressure.

Metal Halide Lamp: A high intensity discharge lamp in which the major portion of the light is produced by radiation of metal halides possible in combination with metallic vapors such as mercury.

Photoperiod: The environmental (natural or artificial) light-dark cycle to which living organisms may be exposed.

Portable Lighting: Lighting involving equipment designed for manual portability.

Rated Life: Standard HID and most lamps – number of operating hours at which 50 percent will still be operating. For pulse start metal halide, the value is set at 70.

Room Cavity: The cavity formed by the plane of the luminaires, the workplane, and the wall surfaces between these two planes.

Room Cavity Ratio: A number indicating room cavity proportions calculated from length, width and height.

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Task Lighting: Lighting directed to a specific surface or area that provides illumination for visual tasks.

Work Plane: The plane at which work usually is done or at which the illuminance (fc) is specified. For example, the cow’s udder for milking parlors or the cow’s eye for long-day lighting would locate the work plane.

8. Lighting Sources and References This Dairy Energy Technical guide primarily utilizes materials reprinted from various sources and were modified to fit the needs of Michigan Dairy.

Primary Source:

Dairy Farm Energy - http://www.dairyfarmenergy.com/Chapter_PDFs/3_Lighting.pdfCenter for. This website was developed by Southern California Edison and DLTech Inc. of Ithaca, NY.

Secondary Source:

Center for Ecological Technology – http://www.cetonline.org/FarmBusiness/vfds.php

Center for Ecological Technology - file:///c:/Farm%20Energy%20Audit/Technical%20Info/Energy%20Efficient%20Lighting.htm

Ensave – http://www.ensave.com/documents/CAVSDProgrampaper03.23.05.pdf

US Department of Energy - Technology Fact Sheet, Improved Lighting.

Alliant Energy - http://www.alliantenergy.com/docs/groups/public/documents/pub/p012396.hcsp

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