Planning a Successful Ventilation Retrofit

September 14, 2020

By: Gabe Sterling, VES Dairy Expert


In a perfect world, every barn would be a new build where ventilation could be entered into the formula throughout the design, engineering, and building process. That fantasy, as you may have guessed, sure isn’t what we at VES work with on a day-in-day-out basis. 


The reality is that a large swath of the ventilation consultations and installations we do at VES are actually retrofits – making changes and adjustments to existing buildings to achieve – or get close to – our ventilation standards.


With that said, the following steps should serve as important points to keep in mind whether you’re considering a retrofit in one of your barns to manage general heat stress, or provide dry cows with an improved animal-centered environment, or help address declining summer milk production or reproductive concerns.


The Telltale Signs


There are four primary clues to look for that will tell you a retrofit should be part of your operational improvement plan.


The number one sign that your facility is ready for a ventilation fit is a dip in summer milk production. That reduction is likely a reflection of at least moderate heat stress in your herd, which leads to a drop in milk production, and can also impact other aspects of animal productivity or health.


In addition to milk production reductions, a physical clue that will crop up in plain sight is the bunching of cows. If cows are clustering in groups during high heat conditions, it can be a critical clue that your herd is battling both heat stress and flies, which can also result from poor ventilation. This grouping behavior is common in herd animals when they are managing a stressor – in this case, heat – as a collective unit. 


The other summer indicator to look out for is declining reproduction efficiency. If your cows aren’t getting pregnant in the summer months, and pregnancy rates stay low until early to mid-fall, that’s another telltale sign that your barn’s ventilation needs addressing, whether it’s replacing some equipment or a wholesale change to your ventilation strategy.


Finally, moving into the fall months, a lagging indicator that a retrofit should be in the cards is an increase in the incidence of lameness. When cows are heat stressed, they spend more time on their feet, leading to additional pressure on the sole of their hoof, which causes reductions in blood flow to the hoof horn producing cells and fat pad below the hoof bone. This reduces overall cushion, amount of hoof horn growth, and causes more wear and tear on the sole of the animal’s hoof.


Items to Consider


The first question we ask customers when starting the conversation about a retrofit is: What are your goals? It’s a loaded question, but one we will walk through with you to further understand and discuss what you would like to accomplish. Are you, and should you be, looking to do a straightforward replacement of existing fans with new, improved, more energy-efficient models? Are you a growing dairy planning for both near- and long-term growth? Or are you looking for the Cadillac of ventilation solutions that will give you complete and total control over airflow, air quality, and cow comfort throughout the year?


The reality is retrofitting is a viable solution for the vast majority of barns and dairy structures. However, VES’ customized approach is based first on your goals as a producer in addition to the current barn configuration along with your available budget.


Limiting Factors


As we mentioned earlier, the vast majority of free-stall and calf barns can be retrofitted, but there are a few major elements that would potentially make them non-viable.


The first element is overcrowding. For example, if a growing operation has a space that’s roughly about the size of a large hotel room, and the producer wants to equip that space to house 100 calves, it’s just not realistic to create a quality animal-centered environment in that area. VES has developed many small barns into well-functioning calf barns when producers follow best practices to avoid overcrowding. 


If overcrowding isn’t an issue, the next thing to consider is the structural integrity of the barn. Specifically, look for leaks or water collection in the barn. This can cause mold and deterioration in wood structures, including sagging purlins and joists, gates sagging, concrete degradation, and major rusting in steel structures. In most cases, mold can be remediated and rusted or rotting elements can be replaced, but it adds to costs and the root factors need to be addressed before retrofitting begins to ensure the structural integrity of the facility. Moisture can also be a result of poor ventilation that causes condensation buildup. 


The final element to consider is electricity service. If a barn has 600 amp service, is using 200 amps, and 800 amps are required for fans, either more power will need to be brought in, or the ventilation strategy will need adjusting. In many cases we are able to design a ventilation system that fits with the level of electricity service. In instances where the resulting electricity requirements are close to the max capacity, we will bring an electrician into the conversation to determine if additional service is required. However, the decision of whether to invest in additional electrical service comes down to the producer’s budget and growth goals. If additional power is something we need to support growth initiatives, then we often move forward with it. If maintaining current cow populations is the plan, then it’s up to the producer’s value judgment.


One thing to keep in mind is that many cutting-edge fans, including the majority of VES’  direct drive PPF, ECV, and AFR fans with Turntide motors require three-phase power. So if you don’t currently have three-phase power to your barn, it may be time to bolster your energy service if you’re seriously considering a ventilation technology upgrade.


Know What to Know


Here’s a little tip: If your dairy ventilation purveyor of choice does not utter the phrase Effective Cooling Velocity, or ECV, you might not be working with the right contractor. 


Effective Cooling Velocity (n.) – The measure of the speed of airflow when it reaches the cow, rather than when it leaves the fan. Target ECV is between 4 and 6 mph over 80 percent of the cow’s living space, with a minimum of 2 miles per hour anywhere in the barn.


At the end of the day, ECV is the measure of quality air-based cow cooling, so if they’re not measuring that, what exactly are they measuring?


Here are some other questions that a professional, qualified ventilation provider will likely ask or need to observe:


Animal Health: 


  • How much is your milk production dropping in the summer? This is far and away the biggest area of concern for producers when addressing upgrades to their ventilation system. It’s both the most apparent indicator of poor cooling and ventilation, and of heat stress, and has the farthest-reaching financial ramifications on the dairy’s performance.
  • Do you experience seasonal changes in the incidence and prevalence of pneumonia? Lung health is another primary indicator of the effectiveness of your ventilation system, the air quality it provides, and its capability to remove harmful gases such as ammonia from your animal’s environment.
  • What trends do you see with your somatic cell count? How about mastitis occurrences? While many factors can influence these health indicators, keeping bedding dry is a big one. An effective cooling velocity over your animal’s stall beds – in addition to proper ventilation – helps accomplish this.
  • Are you battling poor reproductive efficiency? Heat stress can cause significant embryonic loss. That’s especially true when areas such as holding pens or milking parlors are not treated with the same ventilation expectations as free-stall barns. Although cows don’t spend as much time in these areas, if not properly ventilated it could be the bottleneck to your animal’s reproductive success.
  • Does your herd struggle with lameness in the fall months? The impacts of a poor ventilation and cooling strategy in the summer usually play out well into the fall. You can read more on that here later.
  • Do you track your animal’s lying time – what is it? Cows should spend between 50 and 60 percent of their day lying down, promoting rumination, and maximizing blood flow to her udder to make milk. If your herd is on its feet more than that, it’s because you’re likely not creating an adequate air velocity at her lying level to make the microclimate of her stall bed inviting and it may be time for a retrofit.


These are not the only animal health indicators pointing toward a ventilation retrofit, but they should certainly be a part of any conversation when you’re evaluating and considering it.


Operational Layout and Geography


  • What is your current barn layout, and what is your existing ventilation strategy? Ventilation consultants should be discussing with you the pros and cons of both tunnelvent and crossvent barns as well as neutral pressure, partial-neutral pressure, and negative pressure designs. Do you know the volume of air your barn holds and the number of air exchanges you’re getting every hour during every season?
  • Have you identified the direction of prevailing winds on your operation? Let’s be sure we align with them so we’re working WITH mother nature, not against her. This will save you a significant amount of money by increasing fan efficiency and harnessing the power of natural ventilation.
  • What is your manure handling system and do you have any plans to change it in the future? Identifying the location of your lagoons now and for years to come is important. We certainly don’t want to be pulling any air from those directions.
  • What external environmental conditions do you battle and what are the weather patterns in your area? Are the majority of your months dry and hot, cool and comfortable, or cold and snowy? Consider if the natural climate at your dairy is one worth leveraging or if mitigating her undesirable influence is a key goal. Also, do temperature and humidity level trends justify the expense of an Animal-Centered ventilation and cooling strategy.
  • What do crop rotations look like? Corn tends to hold a lot of moisture and can artificially increase humidity levels around dairies. If the farms around yours plant and harvest corn year-after-year, then managing this humidity is something you will need to consider in your planning.


This area can really tell you a lot! If experts aren’t talking about it, you’re not actually talking to an expert.


Growth Goals:

  • What is your current herd size, and what do you want that number to be in five years? This question gives your contractor not just a sense of your plans, but also other factors to consider such as facility size and layout, staffing, and technology needs. If the plan is rapid growth while minimizing overhead, exploring a complete, digitally controlled ventilation system that can be run remotely and doesn’t require the hiring of additional staff will be an important item to consider.
  • Do you have trouble with labor shortages or retaining employees? Automation, although sometimes intimidating due to its rapid evolution and advancement in the dairy industry, can be a friend of yours. Especially when it comes to minimizing labor costs, reducing errors and maintenance, and giving you and your employees more ‘off the farm freedom.’ Find a partner that you can lean on to help you navigate the technologies of leading dairies.


Planning for growth NOW is the best way to set yourself up to achieve it.


Again, these are just the starting point questions you should be prepared to answer, or your partner should be helping you answer. If your contractor doesn’t ask them, then you should be asking them why they’re not.


Don’t Forget About Calf Barns


Spending a lot of money on calf facilities can be a difficult hurdle for many dairy producers to get over. After birth, dairies usually won’t see a profit from a calf until they have entered their second lactation, roughly 3 years in the future. Because of the lag in profitability and the plethora of factors beyond the environment that can affect that profitability, producers are often hesitant to invest in more capital intensive barns that have proper ventilation.


At VES, we see some calf barn retrofitting requests on facilities that are just too small to start with. Properly ventilating a small calf barn can be cost-prohibitive and can sometimes lead to the construction of new, simple barn facilities that can support proper ventilation equipment. 


Calf barns become a significant bottleneck for under-ventilated dairies due to the results of heat stress, which can lead to poor reproductive performance. In the summer, heat-stressed cows exhibit lower reproductive rates, leading to more cows getting pregnant in the fall when high temperatures subside. However, this cycle of cows not getting pregnant on schedule can lead to calf barn overcrowding in the late spring and into the summer.


Weighing Additional Investment


At VES, one of the biggest considerations we deal with on retrofits is determining whether to equip a retrofit with Variable Frequency Drive Fans (VFD). Based on internal studies, while VFD fans cost more upfront, they will absolutely save operations money, in the long run, both on electricity and on maintenance costs.


The other cost component to consider is precision, automated control systems for your operation. At VES, our DairyBOSR system can tie together ventilation, cooling, and lighting systems to optimize energy efficiency, herd health, and productivity throughout the year. While a significant investment, an automated system can go a long way in taking your operation to the next level.


What You Need To Remember

  • Ventilation retrofitting is a viable solution for the vast majority of dairy operations.
  • It is frequently possible to achieve proper Effective Cooling Velocity (the measure of airflow at the cow level) through a retrofit.
  • There are many questions your partner should be asking you about animal health, operational design, and plans for growth. Review them above.
  • It’s important to manage expectations when exploring the investment in a retrofit. The age, structural condition, and the number of cows living in the barn can all impact the reality of what’s achievable.
  • What is your goal? Replacing current equipment with similar fans, or a fully automated, controllable animal-centered environment? An expert can walk you through what would make the most sense for your farm, your animal health, and your bottom line upon further discussion of your individual operation.
  • Consider how calves could benefit from a retrofit. Oftentimes, dairies that need free-stall retrofits to help quell heat stress on adult cows could use similar attention on the smaller and likely overcrowded calf barns.
  • Review the questions and factors above with a dairy expert to be sure your ventilation retrofit gets started off right based on your specific operational needs.