Iowa State University agricultural engineer Jay Harmon says pork facilities often have less obvious energy leaks that they can correct without a large investment of time or money.
Three areas deserve close scrutiny — insulation, ventilation and lighting.
Harmon uses a 1,000-head, 41 × 200-ft. barn loaded with 50-lb. pigs with ventilation set at 3 cfm/head and propane costing $2/gal.
Insulation: If the existing insulation is less than 6 in. in the ceiling and perimeter walls, additional insulation may be warranted. Table 3 and Table 4 show the potential savings and payback timeline. The longevity of the building is always an important consideration in this step.
Ventilation: Make sure temperatures are at appropriate levels.
“Small steps can make a big difference. In one study, the results demonstrated that over-ventilating a facility by 20% could mean increasing propane usage as much as 50%,” he notes (Table 5). The greatest ventilation challenge is loading a facility with pigs in January, but the potential for savings is also greatest.
When controllers aren't set properly, a ventilation system that adds too much heat, then dumps it through ventilation when temperatures get too high, are very costly.
“If you regularly hear variable-speed fans increasing in speed and you hear your heater turning on and off during the same period, the controller probably isn't set properly,” Harmon says. “Variable-speed fans are challenging, because every manufacturer uses a slightly different controller setting. Understanding how that controller works and setting the proper motor curve for your fan is important to maintain the proper air flow and avoid a host of costly problems.”
Nocturnal setbacks may be beneficial. “Manage setbacks properly; don't just lower temperatures without investigation,” Harmon says.
Replace aging fans, thermostats and controllers. All are usually a good investment, sometimes made better with rebates.
Humidity is another measure of air quality. If it's too high, the building is under-ventilated. “There's a fine balance between maintaining the health of the pigs and controlling energy costs.”
Lighting: The differences in energy use of incandescent vs. compact fluorescent lighting (Table 6) are worth consideration, Harmon explains.