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Ventilation and cooling questions and answers

Adam Hatton Published on 17 October 2014

Effective ventilation and cooling of dairy housing facilities are keys to keeping cows safe and productive, lessening health risks and protecting your bottom line. But finding the right fit for your farm depends on a host of factors, including facility design, geography and building orientation.

In search of a solution? Here are some common questions and answers about cooling and ventilation to get you started.




What’s the difference between cooling and ventilation?

The terms seem related, but there are differences. Having both in your dairy housing is ideal. Dairy barns are typically ventilated, either naturally or through mechanical means. This ventilation ideally keeps the barn the same temperature inside as it is outside.

Ventilation is simply air exchange, or the process of replacing the air in your space with fresh air. As temperatures start to slowly climb in the springtime, we open the curtains and ridge vents of naturally ventilated barns to stay comfortable.

But if there’s no air movement, the best you can hope for is to match the outside temperature. That’s great when it’s 65°F – but not so nice when it’s 95°F.


That’s where evaporative cooling through increased air movement comes in. While fans can’t lower the actual temperature in a space, they can lower the effective temperature – how the space feels to occupants. High-volume, low-speed fans, for example, can lower the effective temperature by as much as 10°F. That’s why it’s best to have both ventilation and cooling at work in your barn.


What is the ideal temperature for dairy cows?

The best range for dairy cows is between 25°F and 65°F. When the Temperature-Humidity Index (THI) exceeds 68°F, lactating dairy cows face a potential decrease in milk production, reproduction rates and overall health.

As THI continues to rise, cows can begin to experience heat stress, with consequences ranging from mild changes in metabolism to potential death.

Cows change their behavior to adapt to increased heat stress, becoming less active, seeking shade and crowding into the cool areas of a barn.


They sometimes choose to lay in unsanitary locations, and if they can’t find a cool spot, cattle begin to stand for long periods of time, which can cause additional stress and possible foot problems. Herd discomfort also contributes to a drop in milk production, a lower reproductive rate, lameness, mastitis and a high cull rate.


How much will it cost to cool my cows?

The question should be: How much will not cooling my cows cost me? Studies show that heat stress reduces milk production between 10 and 25 percent, and that can have big consequences for your bottom line.

Take, for example, a 500-cow herd. A lactating cow can produce 80 pounds of milk per day. At a sale price of $15 per hundredweight, that could mean between $600 and $1,500 of lost milk for each day your cows are uncomfortable.

Spread that over the 45 hottest days of summer, and you’re looking at a loss of $27,000 to $67,500 – and that’s a conservative estimate. It’s important to consider the potential for product loss when you weigh your options for cooling and ventilation.

It’s also crucial to look beyond the fan’s sticker price to its long-term operational costs. A fan might be cheaper on the front end, but if it’s less efficient than another model or requires more maintenance, it may cost you more in the long run.


Summer doesn’t last all year. Will I see the benefits of fans and ventilation year-round?

Cooling is their primary purpose, but there are other perks to fans and ventilation in dairy production. Increased airflow can result in drier bedding, improved air quality and better heat mixing in the winter. As you consider your options for ventilation and cooling, keep in mind the overall effect it can have on your dairy operation.


What’s the difference between high-speed fans and HVLS fans?

High-speed fans move air fast and in a direct stream. High-speed, paneled, box or directional fans work well in areas with low ceilings, as well as places that require faster air movement, such as holding pens, milking parlors or feeding alleys.

HVLS fans move large amounts of air more slowly throughout an entire space, from ceiling to floor and wall to door. They are ideal for larger spaces. Introduced to dairy farms in the late 1990s, these energy-efficient fans can save you significant money on utility costs compared with numerous small high-speed fans.


How many fans do I need in my space?

Let the experts tailor a solution for you. Work with a company that employees well-trained salespeople and engineers who can give you the best advice. PD

adam hatton

Adam Hatton
Big Ass Fans