While there’s still a winter chill in the air, the upcoming weather fluctuations that occur as the seasons transition into spring and summer can present more challenges than the consistent cold. Managing energy costs is a full-time task.
Some simple changes and attention to details that are easily overlooked can help you manage your energy costs. For example, proper settings on electric motors that control minimum-ventilation fans during the heating season is one such item.
Every fan motor responds differently to voltage. Pay close attention to motor curves and the resulting fan performance. “By selecting the right motor curve, your controller will be more accurate and more efficient,” says Mike Brumm, Brumm Swine Consultancy, Mankato, Minn.
Just because a motor is working doesn’t mean it’s delivering the proper ventilation rate. “The No. 1 reason producers have excessively high energy bills is because they get the wrong controller settings on variable-speed fans,” Brumm says. “This is a huge problem, and it’s important to get it right. Variable-speed fans are misunderstood by many producers.”
He recommends that you consult equipment manuals or ask the installer if you’re not certain about the setting you’ve selected. A word of caution — the percentage of fan output or percentage of rated rotations per minute does not necessarily correlate to the percentage shown on the controller.
“You can make your controller communicate with the fan much more accurately and efficiently by selecting the right motor curve,” Brumm notes. “To get 50 percent output from a fan, you have to be at 65 percent of the fan’s rated RPM.”
Monitor Air, Temperature, Humidity
Inlet adjustment also plays an important role in efficient ventilation. You should measure how fast air is coming through an inlet and shoot for 800 feet per minute, which translates into 0.05 inches of static pressure.
Check that your temperature and humidity sensors as well as controllers are working correctly and are set to properly maintain the building’s temperature. When adjusting settings, remember that barn humidity fluctuates throughout the day. Barns are driest in the morning, with humidity rising as the afternoon and pig activity progresses.
It may take some experimenting to select the point at which ventilation is initiated. “Try to get an average,” Brumm suggests. “If you use a humidistat in the barn to help initiate ventilation, put a new filter on the device every fall.”
Don’t neglect electric motors that are used to pump drinking water, flush manure or move feed from the bulk tank to the feeder lines. Worn or inefficient motors, belts or fans can significantly add to operation costs. According to USDA’s Natural Resource Conservation Service, a worn belt can easily reduce output 20 percent or more. Other studies show that loose belts can reduce fan output as much as 50 percent, and of course that will add to energy costs.
Furnace offset is another mistake that’s routinely made. Brumm recommends setting furnaces to turn off 2 degrees before the set-point is reached. “When you are in furnace mode, if your daily high temperature is above your set-point, you’re wasting propane,” he says.
Prevent Air Leaks
The biggest air leak in hog barns usually occurs from ill-fitting pit covers. “You want fresh, clean air brought into the building, but since a fan doesn’t care where the air comes from, it will pull air out of the pit and deliver it to the pig space if pit covers are not tight,” Brumm says. “Ensuring tight pit lids is critical to getting proper function from ceiling inlets and to move the correct air into the barn.”
He reminds producers that only 7.5 square feet of total inlet area is necessary when two, 24-inch pit fans are operating at 50 percent capacity. The 6,000 cfm of ventilation associated with this setting is often the starting point for minimum ventilation when feeder pigs are placed into a 1,200-head facility. “Five, 6-inch by 6-inch holes in a curtain would provide 17 percent of the inlet requirement for a barn,” says Brumm. “Curtain maintenance is very important.”
In checking your barns for energy efficiency, it’s a good idea to make sure emergency equipment is operating properly. You need to be prepared for winter emergencies like power outages and excessive snow or ice. Brumm recommends checking the building perimeter and equipment regularly, including emergency curtain drops. Also, become familiar with insurance policy requirements.
Test transfer switches on back-up generators; date, sign and record that information. In the event of pig deaths, those records will show your insurance company that the equipment was functioning properly.
Check the “Little Things”
Insulation is too often overlooked, which is unfortunate because over time it deteriorates and becomes less effective. Check the building’s ceiling and perimeter insulation levels. Ceiling insulation may settle or get pushed around by the wind, creating bare spots.
“In areas of a building where there is no insulation or there are bare spots, it’s worth the time, money and effort to add insulation,” says Jay Harmon, agricultural and biosystems engineer, Iowa State University.
Your savings depend on how much your current insulation can be improved. For example, increasing ceiling insulation from R-30 to R-40 could net less than $100 per year. Increasing from R-10 to R-40 could result in more than $500 in annual energy savings. Of course, R-values and your insulation needs are influenced by your geographic location and climate, but it’s worth checking your insulation prospects.
Young pigs are especially vulnerable to problems that inadequate insulation causes, such as cold spots and drafts. “Radiant heat loss may occur in young pigs and lead to illness or poor performance,” Harmon warns.
Poor perimeter insulation can lead to cold floors that are wet from condensation. “Buildings with no perimeter insulation that house small pigs may have animal-comfort issues,” he notes. “Adding insulation in these cases will usually pay for itself, perhaps more in pig performance than in actual energy savings.”
Even though it’s not a glamorous job, fan maintenance can add up to savings. Without clean and efficient fan blades, shutters and discharge cones, all your other energy-saving efforts are tempered.
For best results, follow a regular cleaning and maintenance schedule to keep the ventilation systems running efficiently. “You must clean the fans,” Brumm emphasizes. “One-eighth of an inch of dirt on fan blades can reduce air flow by 40 percent.”
If discharge cones are broken, their function may be reduced as much as 30 percent, so get them repaired.
Switching to compact fluorescent bulbs will pay for themselves even though they present a higher initial cost than incandescent bulbs. Harmon compares a 75-watt incandescent and a 20-watt compact fluorescent bulb, which both produce about the same lumens. If the bulbs operate 8 hours a day, the compact fluorescent bulb costs about $6.50 annually while the incandescent bulb will cost roughly $23.50.
Focus on proper ventilation management. “Getting a building’s ventilation settings correct is by far more important than insulation and lighting to manage energy costs,” Harmon says, “and a key factor is getting the motor curve set correctly on your controllers. Also, keep in mind that may vary from building to building.”
Think of all the various factors as a system — the set-point, offset, motor curve, fans and curtains. Make adjustments slowly and shoot for optimum ventilation rates, Harmon suggests.
If you take the time and make the effort, you can tame energy costs. By getting to know your ventilation system settings and all of its components, you will be well on your way.
Don’t Overlook Energy-saving Basics
By keeping a record of pig performance, energy use, building temperatures and humidity, as well as fan settings, you will begin to see just where your settings need to be for optimal energy efficiency and animal performance.
While conditions vary from barn to barn, Jay Harmon, agricultural and biosystems engineer, Iowa State University, suggests evaluating the following action items for efficient winter operations within your own system.
- Widen controller bandwidth on variable-speed fans; he suggests a 2-degree bandwidth.
- Use the proper motor curve to control minimum fans. The dealer or manufacturer can help you select motor curves to get the proper settings for specific situations.
- Provide a gradual increase in ventilation and avoid large jumps in rate.
- Re-examine the stop-settings on inlets; make sure mechanical ventilation is not restricted.
- Watch building temperature settings; Harmon sees more hog barns that are kept too warm rather than too cool. For 200-pound pigs, 62˚ F to 64˚ F should be adequate. Market-weight pigs should do fine with temperatures around 59˚ F. Of course, that’s at the pig’s level, not yours.