The dairy industry continues to seek the ideal ventilation system for dairy barns.  

Producers are turning to automation to save labor and provide an environment that adapts to the cows’ needs at any time of the day or night. Let’s take a look at some of the options for keeping cows comfortable year-round.

Insulate to automate

Some basic ventilation trends can be learned from other animal production agriculture, such as the poultry and swine industries. For instance, one common trait of other production barns is an insulated ceiling. Insulated ceilings are proven to reduce the inside barn temperature by a minimum of 10ºF.

Insulated barns don’t sweat in the winter, and they reduce radiant heat under the roof on hot summer days. They also give you more year-round control to adjust temperature and ventilation through automation.

Dairy barns need two separate air systems

There are two very different air systems in dairy barns. One system exchanges the air (ventilation), while the other provides directed airflow (airspeed) on the cows. Trying to achieve both with one fan system is nearly impossible and always results in very high operating costs. Air has a natural tendency to take the path of least resistance and looks for places to escape.


As cows lie in rows or stand at the feedbunk, the air looks for paths around them. Dairy barns are big buildings with many large openings for cows or equipment to move in and out, which allows air to sneak out too. Engaging two systems solves these problems efficiently and delivers the ultimate climate for the cows.

Air exchange system

Good air exchange is the first step of ventilating a barn. In dairy barns, air exchange can be achieved by either natural or mechanical ventilation. Naturally ventilated barns have open sides or curtain walls that can open to allow fresh air to enter.

Mechanical or power ventilation is a combination of inlets and fans that control the amount of air moving in and out of the barn. Tunnel, cross or tunnel-plus ventilation are examples of mechanical ventilation systems. Some producers prefer a solid sidewall to help maintain a more constant climate year-round and avoid crosswinds.

Regardless of the type of ventilation, there are several control options to constantly adapt the barn environment to the cows’ needs. These controllers take into account temperature, wind direction, rainfall and other factors to automatically adjust curtain openings, roof vents, fans, etc.

Air curtains that operate with a simple air blower to open and close are growing in popularity and also add insulation to your sidewalls.

Automating your air exchange system provides more consistent delivery of fresh, clean air to every cow. They are also able to adjust for climate conditions such as storms, crosswinds or sudden changes in temperature, which may have otherwise gone unnoticed.

Airspeed system

Once sufficient air exchange is in place, airspeed can be added to enhance cooling. Fans over the stall rows and feedbunks focus precise airspeed in the areas where cows are typically located. When it comes to cooling, the higher the airspeed, the better. Fans currently on the market generally provide 15 to 22 mph off the fan face, while the newest fans provide up to 36 mph off the face.

Along with new fans come new controllers that allow infinite adjustability and more precise cow comfort. Thermostats can be used to stage fans on as temperatures increase. Variable-frequency drive (VFD) motors and new “electronic commutative” (EC) variable-speed motor fans are gaining in popularity.

These fans automatically ramp their speed up and down to further improve air quality and cooling based on cows’ needs. In addition to increasing cow comfort, some new motor technology can reduce energy costs by as much as 50 percent. Energy efficiency grants are available for these fans in most areas.

Water cooling systems

Adding water to your heat abatement program dramatically increases the effectiveness of ventilation and airspeed. Many options are available, each with their own level of success and improving over time.

One of the earliest forms of evaporative cooling in barns is a sprinkler along the feedbunk. This is effective at providing some heat stress relief; however, it results in massive amounts of water waste (as much as 40 gallons per cow, per day) and causes an unbalanced barn, with cows standing at the feedbunk or lying down in the aisle.

Fogging systems and evaporative cool cells focus on cooling the air temperature. While they work well in lower humidity, maintenance issues are a concern, and fan power can be reduced when blocked inlets affect static pressure.

Low-pressure water systems that deliver water into the fan’s airstream can be quite effective. They allow cooling over the stalls, which leads to more lying time. Their low water usage makes them a good option for freestalls, feedbunks, tiestalls, bedded packs, holding pens and hospital areas. Keep in mind that fans and airspeed are an important first step before adding water.

As with ventilation and airspeed systems, automated controllers are now available to operate these water systems. Many take into account temperature and humidity, and adjust the settings accordingly. These controls make cow cooling automated 24-7 by adding the right amount of water exactly when needed.

Three systems = complete solution

Building a dairy barn is a big investment that typically costs several thousands of dollars per stall. Without proper ventilation and cooling, that investment is wasted while cows stand in aisleways and lose production.

Basic upgrades such as VFD can have a minimal cost, while high-tech upgrades may require a little more investment. These additional costs are small compared to the return on the investment. Improvements in ventilation and cooling often pay for themselves in just a few years or less.

The dairy industry must use automation to increase comfort in every area of the barn. Technology continues to evolve and improve these systems, opening the door to never-before-seen levels of milk production per cow and better conception rates.

A small investment today in automating your ventilation and cooling systems can ultimately result in the ideal environment for cow comfort.  PD

Brent Hershey is an airflow and cooling specialist at CowKühlerZ. Send Brent an email.