It’s today’s reality — energy costs are taking an ever-increasing bite from your wallet. If this winter is anything like last year’s, you will get a harsh reminder regarding electricity and heating fuel bills. Fall is a prime time to evaluate your barns’ energy profile and set your sights on making cost-saving improvements.
The ventilation system is an ideal place to begin. Since under-ventilating creates an unhealthy environment and over-ventilating wastes valuable heating energy, finding the right balance is a step toward energy savings and efficient production.
“Winter ventilation represents the biggest potential for wasted energy,” says Jay Harmon, agricultural and biosystems engineer, Iowa State University. He estimates that over-ventilating by as little as 10 percent can increase annual LP consumption by 27 percent.
Achieving the correct barn ventilation rate doesn’t cost anything, but it can provide instant payback in reduced propane use. “For wean-to-finish barns in climates such as Iowa, shoot for 2 gallons of propane per pig space per year,” Harmon says. For Minnesota, and similar climates, it may be closer to 2.5 gallons.
Ventilation is necessary for a healthy production environment, and while saving on your energy bill is important, pig comfort also is a priority. (See the accompanying table for minimum ventilation recommendations.)
To align both objectives, you must size the ventilation fans appropriately for the room. “Choose fans that are within the upper one-fourth of rated fan efficiencies,” Harmon says. “Size variable-speed fans to run no slower than half of the full-rated speed, as slower speeds may burn out the fan motor.” This generally equates to approximately 40 percent of rated capacity.
Of course, you have to adjust the rates based on humidity and ammonia present in the barn. “If the relative humidity is higher than 60 percent in the morning or 75 percent in the mid-afternoon, or if ammonia seems high, increase the speed,” Harmon says. “If the relative humidity and gases are low, try reducing the fan speed slightly.”
Finding the ideal minimum ventilation is sometimes a matter of adjusting the controller and evaluating environmental conditions within the barn. However, understanding the relationship between the controller and the fans can be a challenge. For example, if the minimum ventilation rate recommended for a 1,200-head, wean-to-finish barn is 2,400 cfm and your fan delivers 6,000 cfm, you will need to reduce the voltage to that fan. However, at 50 percent voltage, it may only deliver about 800 cfm. “Fifty percent voltage does not mean 50 percent delivery,” Harmon explains.
Information from the controller manufacturer should offer fan motor curves, fan compatibility settings or motor compensation factors to help you achieve the desired ventilation rates from your variable-speed fans and reduce energy consumption. (For more information, go to http://bit.ly/rlB1NG.)
If it’s time to buy new fans, calculate savings in energy before selecting the fan. “Our most efficient 24-inch fan is rated at 17.1 cfm per watt,” Harmon says. “It would use $310 of electricity annually, while the least efficient fan would use $537.” If you’re considering new fans, check with your energy supplier for rebate allowance offers.
Cleaning and maintaining your current fans are priorities for efficient operation. Start with the fan shutters. Dirty shutters can reduce fan efficiency by 40 percent. But more than that, if fans aren’t running efficiently, they may trigger another stage of ventilation, in which case you’re paying for additional energy.
Pit fans are notorious for caking with debris. As pits fill up, fan efficiency declines markedly. To move air you may have to run wall fans because the pit fans are moving less air.
The Furnace Factor
Proper furnace management is another priority in winter. If furnaces are not sized appropriately, you will waste propane. What’s more, furnaces are often oversized. “When furnaces are oversized, it often leads to an increase in the ventilation rate,” says Mike Brumm, Brumm Swine Consultancy, Mankato, Minn. You have to get the proper controller setting to avoid wasted energy.
“A lot of controllers are set wrong in production facilities, causing excessive propane usage and significant over-ventilation of facilities, especially at the time of pig placement,” Brumm says.
As Harmon points out, “If fans are increasing in speed when furnaces are running, or after they shut off, you will need to adjust the furnace offset or temperature setting in the controller.” He suggests listening for the tell-tale sounds for needed adjustments.
“When the furnace runs and shuts off, the room temperature should never get to the set point. For most controllers, this means the furnace should shut off 2° F below the set point,” Brumm says.
Since furnaces are sized for the coldest months, they may produce less efficient results during fall operation. “If your furnaces have a variable-output valve, it should be at the low setting during October and November,” Brumm says.
As for insulation, will adding inches to the ceiling and walls pay off? While it may improve animal comfort or increase building longevity, from an energy savings standpoint it may not offer enough return. “If you have 5 to 6 inches of insulation in the ceiling, adding more is probably not a priority,” Harmon says.
Let the Pigs Tell You
Achieving the right temperature for piglets is a challenge, and there’s little substitute for observing the pigs. Especially with young pigs, if they’re spread out and not touching while they’re sleeping, it suggests that the ambient temperature is too high. Conversely, if piglets are huddled together, the room temperature is too low. The question is, “is the ambient temperature you’re running comfortable to the animals?” Harmon says. “Finding the right temperature will depend on your barn.”
Factors that cause variation include perimeter insulation and placement of the temperature sensors. Zone heating can help maximize young pig comfort while allowing a lower room temperature. Harmon points out that by switching from 250-watt heat lamps for baby pigs to 175 watts, pigs may actually be better off. The higher-wattage lamp may warm pigs too much, to the point where they have to move away from the hot-spot and end up in an area where the sow could step or lay on them. Iowa State research showed that using lower wattage heat lamps can actually increase the number of pigs weaned per sow per year.
Record your energy costs, begin tracking your facilities' energy-use status and establish efficiency goals. Then it will be easier to focus efforts on the areas that can make a big difference in your energy consumption. For an energy efficiency checklist and additional resources, go to http://bit.ly/p9dSMX.
See the Light
Before long, conventional incandescent light bulbs will be phased out and replaced with compact fluorescent bulbs. “Fortunately, CF bulbs are much more efficient than incandescent, providing more lumens per watt,” says Jay Harmon, agricultural and biosystems engineer at Iowa State University.
While CF bulbs are more expensive, they will last two to three times longer than incandescent bulbs, and the savings will soon add up.
For example, in a light operating eight hours a day for one year, or 2,920 hours, an incandescent bulb will burn 219 kilowatts while the CF bulb would use 58 kilowatts. By investing a little extra in CF bulbs upfront, Harmon expects you will save $18 per bulb annually.
A 900-head gestation barn, with 150, 75-watt incandescent bulbs running eight hours a day, would use 32,850 kilowatt hours per year. For the same barn, the CF bulbs would use only 8,760 kilowatt hours. At 10 cents per kilowatt hour, the CF bulbs would save $2,400 annually.