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Identifying Opportunities For Energy Cost Savings

It’s easy to waste money if you don’t understand how hog barn heating and ventilation systems work, or most common causes of energy wastage.

“To be able to run the entire system at optimum performance without wasting energy, the operator has to know each component very well, in addition to understanding the related factors that affect the operation of the system,” Dr. Bernardo Predicala of the Prairie Swine Centre told attendees at the recent Red Deer Swine Technology Workshop.

Studies conducted by the centre have found that utility costs ranged from as little as $5 to as much as $12 per hog marketed, meaning there is an opportunity to significantly cut costs on many farms.

Observation of pig behaviour and comfort is the first step in determining whether ventilation settings are correct.

“Even if the controller shows that the air temperature is right on the recommended set-point, the pigs may still show signs of discomfort if other environmental factors are not right, for example if there is a cold draft, floor slats are too cold, or humidity is too high,” Predicala explained. “If any of these factors are incorrect, it indicates the need for adjustment of the appropriate ventilation system components.”

Even if the system maintains good pig comfort, it does not mean it is energy efficient, he said. Overventilation is one of the most common problems and is not always easy to identify. Exceeding the required minimum ventilation rate by just 10 per cent in a grower barn results in a 27 per cent increase in propane consumption, he noted.

“As barn operators can see only the air temperature from their controller display and not the airflow rate, they may not be aware that they are overventilating their barn, particularly if there are no apparent adverse effects on the pigs,” said Predicala. “A detailed analysis of the controller settings, coupled with observations and measurements of fan and controller operations would yield an estimate of the actual ventilation rates relative to the required values. The bottom line is that overventilation can be resolved by finetuning the ventilation settings carefully, which requires virtually no monetary investment to realize savings.”

Another cause of overventilation is improper sizing of minimum ventilation fans.

“A common mi stake is installing a variable-speed fan with too large a capacity so that it cannot be slowed down sufficiently to meet the required minimum ventilation rate level.”

Static pressure, which is a measure of the resistance to air movement through the ventilated airspace, is often a neglected parameter, Predicala said.

“As the air moves through the air intake, ducts, inlets, shutters, and hoods, these structures inevitably present a resistance to air movement. The higher the static pressure, the harder the fans need to work to overcome this resistance, therefore requiring more energy,” he said. “Static pressure levels can be managed by setting openings properly, specifically the inlets through which air enters the ventilated room. The size of inlet openings should be adjusted such that the speed of the jet of air coming out of the inlet opening is between 3.6 to 5.1 metres per second (700 to 1,000 feet per minute) and overall static pressure is between 10 to 25 Pa (0.04 to 0.10 inches of water) as measured by a manometre.”

Exceeding these static pressure levels causes a significant reduction in fan airflow rates, requiring more fan energy to pull the required volume of air through the barn, Predicala said.

Incorrect “staging,” or synchronizat ion, of fans and heaters can result in excessive exhausting of heat from the room.

“A common mistake is improper setting of the heater OFF such that the heater continues to add heat to the room up to a point that it triggers an increase in the operation of the ventilation fans,” Predicala noted. “Sensors have a lag period when sensing the actual room air temperature, (so) the sensor would register a continued increase in room air temperature even after the heater had already turned off. Thus it is recommended to have the heater OFF at 1.0 to 1.5 C below the room temperature set-point to avoid overshooting the set-point and triggering an increase in the speed of the ventilation fans.”

Similar to most other aspects of pork production, an energy and cost-efficient barn requires evaluating how, where, when, and how much energy is being used in different areas, Predicala said.

“An energy audit will yield detailed information on energy usage as well as identify target areas in the barn and the appropriate measures that can be applied to either reduce energy use or improve efficiencies,” he said. “Also, having baseline information on past and current energy use in the barn will serve as reference for determining the potential savings from energy conservation measures being considered for the barn, as well as in figuring out the actual savings if you do decide to implement these measures.”

Above all, understanding the system is the key to optimizing energy use, Predicala concluded.

“Most of the common heating and ventilation mistakes can be either avoided or resolved by having sufficient knowledge of the operation of the system,” he said.

Modern ventilation controllers are very sophisticated in their capabilities but may be intimidating to the operator, he said.

“While proper operation of these modern systems yields greater benefits in terms of better efficiencies, not being able to operate the system correctly could result in really poor conditions and significant energy wastage.”

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BERNIE PEETPeet onPigs

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