Air circulation is a critical element of any successful horticultural endeavor. Though air exchanges for temperature control are often the more obvious necessity, air circulation is just as important to maximize the success of any horticultural operation. While we focus on plants in this article, most of these principles also apply to air circulation for animal and human comfort.
Too often air circulation is overlooked in horticultural settings. Plants may be able to survive with insufficient air movement, but they will never thrive. For most plants to reach their full growth potential air movement is just as critical as the quality of light or nutrients. Many production facilities are designed with little to no air circulation. Circulation fans that are present can often be inefficient and noisy which can further discourage their use.
Benefits of Optimized Air Circulation
Plant foliage has tiny openings called stomata on the undersides of all its leaves. These stomata are quite literally like tiny mouths through which the plant breathes. Plants expel oxygen (O2) and water vapor from the stomata and take in carbon dioxide (CO2) to fuel their growth. When wind speeds are too low or too high these stomata remain closed to protect the plant. When closed, the plant’s transpiration and photosynthesis will be compromised, and plant growth will suffer. Appropriate air circulation both stimulates the stomata to open and delivers fresh CO2 to the leaf surface where it can be absorbed by the plant.
At the same time as the air circulation delivers fresh carbon dioxide to the plant’s leaves the air will also wick away humidity that builds up at the plant level due to the plant’s release of water vapor into the air. If left unchecked this humidity can increase to unsafe levels that can encourage the growth and persistence of pathogens like molds, mildews and biological pests. These pockets of higher humidity, and often warmer air, are referred to as microclimates and result from stale air becoming trapped within plant canopies. Even if temperature and humidity readings are acceptable in the open air, it is often the case that environmental levels can vary dramatically within the plant canopy. Without sufficient air circulation throughout the crop environmental inconsistencies can compromise plant growth and even cause disease and plant loss.
Types of Circulation Fans
There are two common fan solutions to homogenize the air within a cultivation space. Horizontal Airflow Fans (HAF Fans) have long been a standard practice to help circulate and destratify the air in growing environments. Without sufficient air movement, moisture in the air will condense on plants and other surfaces as the temperature falls below the dewpoint. Condensation on plant foliage increases instances of disease. To prevent this, HAF fans are hung within a space to create a current of air movement inside which helps to prevent condensation. The air current also encourages the mixing of air, preventing warm rising air separating from the cool air settling toward the floor. It is generally beneficial for these fans to run constantly. A well circulated growing atmosphere helps plants thrive any time of day and improves the efficiency of other HVAC equipment in the process. Despite these benefits, traditional HAF fans are frequently installed too far apart and hung too high to effectively deliver fresh air throughout dense plant canopies. Common HAF fans also produce a narrow stream of air that is not always capable of penetrating down into plant canopies.
Another type of fan designed to combat air stratification is a vertical airflow fan (VAF Fans). These fans blow air up or down perpendicular to the floor, to drive the intermixing of warm and cold air layers within a space. This mode of air circulation can be an energy efficient way to destratify the air in a space, especially one with high ceilings. VAF fans alone are generally insufficient to meet all the airflow needs of the crop underneath. VAF fans draw free air up and through the fan, but do not present a natural horizontal air pattern to the plant canopy that can penetrate through foliage and reach the plant stomata effectively. When this is the case stale air builds up in the boundary layer around plant foliage, trapping humidity, limiting gas exchange and hampering growth.
Efficient Control Pays Off
Because it is important to keep circulation fans running as much as possible, the cost of operation is sensitive to the efficiency of the fans themselves. New motor and control technology is bringing improvements to air circulation, with significant cumulative cost savings on energy. Variable speed control for air circulation is also a worthwhile feature. Speed control allows operators to tune air speed to meet their present need, while simultaneously allowing for a further reduction in fan electrical consumption.
Tremendous benefits in plant yield and vitality can be gained by optimizing the air circulation provided to any crop. Air circulation fans can provide a tremendous return on investment in the form of harvest improvements.
Are you looking for an air circulation fan or HAF fan for your industrial or agricultural space?
Snap-Fan Crop Level Airflow fans are more effective than the typical HAF fan. Snap-Fans have been carefully designed to provide optimized Crop Level Airflow through the plant canopy. Fan design and blade technology combine to deliver more air at the right speed to plant stomata, invigorating growth and vitality. Energy efficient and speed controllable fan motors provide round the clock cost savings and tunability for any point in the plant lifecycle. Browse through our catalog of Snap-Fan options. Our high-quality fans are built to be effective, long lasting and efficient.
