by Sanne Kure-Jensen
A recent webinar, “Lighting Systems: Analysis, Performance, and Energy Conservation Opportunities,” described agricultural lighting system functions and how new systems can improve efficiency and performance. Dan Ciolkosz of Penn State described lighting system vocabulary, design and its impact on people, animals and plants. Kip Pheil of USDA NRCS National Energy Technology Development Team described NRCS practice standard 670 – Lighting System Improvement, used to implement lighting system upgrades.
The lighting industry uses its own terminology. Lumens, foot-candles and lux are measures of light level reaching a set area. Bulbs are called lamps. Fixtures are called luminaires and may include a bulb, ballast, reflector and lens. Fixtures will have a photometric report including performance data and where it can be used.
Many fixtures and bulbs that work in offices or factories under dry, clean environments may not function properly in damp, dusty barns or in environments with corrosive vapors. Farmers and agricultural lighting system designers should seek sealed fixtures and controls rated for “damp” or “wet” conditions, or with Ingress Protection (IP) ratings of 55 or 65.
Typically, an efficient lamp and ballast convert about 30 percent of electricity into light and 70 percent into heat. Fixtures, lampshades, floors, walls and other surfaces may absorb or reflect some of the light. Often just 10 percent of the energy used actually reaches the work plane or area needing light. High efficiency lighting fixtures convert more power into visible light and generate less heat than inefficient fixtures do.
One way to save significant energy in greenhouses or free stall barns is by switching from incandescent or older fluorescent to metal halide systems. The new fixtures should be mounted high and utilize a pulse starting system to improve efficiency and extend their life. Metal halide bulbs offer good color rendering.
General lighting is often uniformed and may be relatively dim or have low intensity in common areas like hallways. High light levels improve visibility and safety when well designed to prevent glare. Task lighting is focused where work needs to be done or where higher light levels are required. Properly lit dairy parlors often have a combination of general and task lighting. Many farm spaces should be well lit including milking parlors, areas for equipment washing and maintenance as well as maternity and veterinary care. Greenhouse growers need well lit seeding, transplanting and growing spaces.
Moderate light levels are sufficient in holding pens, areas for feeding, sorting/observation as well as general cleaning and repair. Low light is sufficient in livestock stalls, walkways, equipment storage, refrigerators and areas where lighting is used for photoperiod control.
Animals generally respond to light like humans though each is sensitive to a somewhat different spectrum. Higher light levels lead to increased feed rates. Lower light can reduce aggressiveness in poultry and swine. It can be cost effective to use artificial light to create longer days to a trigger livestock response. Dairy production can be increased well beyond the costs of energy and inputs. Swine and horses also react well to longer daylight hours.
NRCS follows the ASABE recommendations for Dairy/Livestock illumination* including:
• Milking parlour pits and near udders – 500 lux
• Milking parlour stalls and return lanes – 200 lux
• Holding areas – 100 lux
• General milk room lighting – 200 lux
• Washing area – 750 -1,000 lux
• Dairy housing and feeding – 250 lux
* Source: American Society of Agricultural and Biological Engineers
Plants benefit from uniform light more than animals do. Research and commercial greenhouses need fixtures with appropriate spacing for uniform light. Milking parlours can have slightly more variability. Areas for livestock and equipment handling can have higher variability as can low intensity common areas like hallways.
As bulbs and fixtures (lamps and luminaires) age, they produce less light. A good design accounts for this with systems that produce higher initial light outputs than target levels so that reduced performance later will be at target levels.
Ciolkosz said the relatively short life of incandescent bulbs meant they would often be replaced frequently enough to avoid getting significantly dirty. Long life, high efficient bulbs and fixtures will need regular cleaning. Removing dirt will increase light output and light benefits. Be sure to clean reflectors and check sockets at least twice a year. Clean reflective surfaces like walls and ceilings monthly. Use a light meter or smart phone app to check light output. You may have to replace bulbs before they fail, if the light levels have degraded too low below target levels.
Wiring needs are similar to residential or commercial installations with minor exceptions. Work areas need switches at all main entries. Wall switches should be 48 inches off the floor. In livestock barns, switches should be 72 inches above floors. Fixtures should be sealed to exclude dust, moisture corrosive materials or gasses. Fixtures at risk of damage should be enclosed in a guard to protect livestock and people. Fixtures in damp areas or which could be splashed, must be watertight.
Ciolkosz urged people looking at new fixtures or luminaires to check their photometric reports, not just the bulb’s light output. Be sure the fixture can “get the light out into the space,” he said. Use supporting documents supplied with all fixtures called luminaire photometric reports. Compare their luminaire optical efficiency with other fixtures.
Ciolkosz acknowledged that agricultural lighting systems do not have simple yellow stickers with monthly energy use like energy star appliances. Finding the most effective lighting system “will take some digging,” he said. There is not industry standard efficiency ranking or listing. Lighting companies continue to improve their fixture efficiency.
When looking at replacing bulbs and lighting fixtures, start with the lights that are on the longest. Be sure the potential savings will offset the installation costs. Calculate the payback period. The payback years is equal to the cost of installation divided by the annual savings expected from the new system.
When the payback is reasonable, Pheil suggested farmers and growers reach out to local USDA NRCS or Rural Development staff. Both agencies offer programs to help cost share energy audits and the installation of energy-saving lighting systems. A producer can perform a simple self-assessment with an online calculator and get more help from an NRCS field office.
Efficient agricultural lighting systems and energy conservation opportunities
by Sanne Kure-Jensen