Preparing your swine barn for winter


Quick facts

Help ensure sure your pigs and workers have a good environment throughout winter without high fossil fuel costs.

  • Make sure the barn is “tight” enough to maintain adequate static pressure during outside temperatures less than 0 degrees F or minimum ventilation conditions.
  • Check “winter” room inlets to make sure they are properly adjusted, AND that there are enough attic or hallway inlets to supply air to these winter room inlets.
  • Check winter fans and heaters for proper operation. Also make sure the settings on the fan and heater controllers have a large enough offset so that heaters and second stage fans don’t run at the same time.

Keeping your barns tight

It’s essential for you to keep mechanically ventilated barns and curtain barns “tight.” Make sure a slight vacuum or static pressure exists in the barn when only the continuous running exhaust fans are on. A general target for static pressure is 0.05 inches of water when measured with a manometer.

Every pig barn (or room) needs a manometer to monitor static pressure in the barn. The very minimum static pressure is 0.02 inches of water when your minimum or continuous running fan is operating. If you can’t maintain a slight vacuum or static pressure in your barn, you won’t be able to control the air exchange and quality in the barn.


Adjusting sidewall curtains naturally ventilates curtain barns in warm weather. During the winter, you should close and seal these curtains as tight as possible. Usually, if there’s enough exhaust fan capacity (e.g. 50 cfm/pig in finishing barns), you can physically seal the curtains. This may include nailing them shut or another permanent sealing method. With this exhaust fan capacity, there’s also enough ventilation to control inside temperature rises during warm winter days.

Shutters or louvers of large summer operating fans are the most common leak sources in regular tunnel or other year-around mechanically ventilated swine barns. We recommend sealing louvers on large fans that only run in warm weather. Sealing with insulated panels or heavy plastic will prevent air from flowing back through these fans. Make sure to seal other building leaks (around doors and windows) to prevent these “undesigned” openings from allowing air to enter the barn.

Checking inlets

After making your barn tight, make sure air enters the barn or room where it’s designed to, usually through ceiling inlets. To allow air to enter the room through the gravity or actuator-controlled inlets, the inlets need to:

  • Be operating properly
  • Not be stuck
  • Not have excessive dirt

If the inlets take air from the attic, you must have sufficient attic openings to “feed” air to the ceiling inlets. Typically, these attic openings are eave inlets. Most buildings will have eave inlets on both sides of a mechanically ventilated building. During winter, we recommend that you leave only one side (south side if barns runs east and west) open. This will allow enough inlet opening to feed the barn’s winter air exchange and prevent snow “blow through” in the attic during snow storms.

You may use other attic openings such as gale end louvers or ridge vents to supply air for the ceiling inlets. You should make sure there’s more attic opening (we recommend twice the area) than ceiling inlet area.

The same guidelines for supplying inlet air apply to a tempered or headed hallway in farrowing or nursery barns.

Checking winter fans and heaters

Check ventilation components to make sure they are working properly.

  • Exhaust fans
  • Inlets
  • Heaters
  • Controllers

You should clean fan shutters to increase fan efficiencies and to make sure airflow rates keep good air quality inside the barn. Dirty or rusted, restricted shutters can reduce airflow capacity of a direct drive fan by 40 percent. If you have large belt-driven fans operating in the winter, make sure belts are properly tight or airflow rates may decline (50 percent or more).

Clean and adjust gas-fired heaters so there’s a proper mixture of fuel and air. Heated air from any heater (electric or gas-fired) needs to spread throughout the room to reduce differences in room temperature.

Make sure that the temperature controller (or thermostat) for the heater offset (temperature when heater shuts off and next stage exhaust fan turns on) is at least 2 degrees F. This 2 degree F difference will typically prevent heater “overshoot.”

Heater overshoot is when the spike in room temperature from the heater operating triggers the next thermostatically-controlled exhaust fan to turn on. This can be expensive since large amounts of heated air will go to waste if the heaters and large second stage fans cycle. Overshoot also results in wide temperature swings that are harmful to pig growth and health.

Larry Jacobson, emeritus Extension engineer