Maintaining optimal temperature and airflow in large, open areas has always been a concern for processing facilities. Plant managers have approached this problem in a variety of ways, including the installation of heating, ventilation and cooling (HVAC) systems and the use of traditional floor and/or ceiling fans, either as stand-alone equipment or as a supplement to the HVAC system.
In recent years, however, an increasing number of facility operators have realized that there is another tool that can move air more efficiently, increasing worker comfort and helping extend the life of the HVAC system in the process – high-volume, low-speed (HVLS) fans.
By moving large volumes of air in a controlled manner, HVLS fans make HVAC systems more efficient, while significantly improving the comfort and health of workers 365 days a year. They also help reduce energy consumption, combat air quality issues and can even be integrated into building management systems (BMS).
Traditional high-speed fans have been used to cool buildings and circulate air for decades. And while they can deliver a helpful breeze to workers at a specific distance, they also are notorious for loud and distracting noises, long cords that can become trip hazards and large energy consumption.
The problem within these traditional fans is the speed. High-speed ceiling fans spread out air quickly, but the result is that little (if any) air reaches people working on the ground. In addition to being noisy and disruptive, studies show that air moving faster than 5 mph can be disruptive and provides little, if any, added cooling benefit.
At best, these fans can help distribute air from an HVAC system into small areas of a large facility. However, high energy consumption and limited performance result in high-speed fans providing little return on investment.
Slowing it down with HVLS
While it might seem counterintuitive, lower speeds can actually provide more benefits in large buildings with high ceilings. Thanks to specially designed blades, HVLS fans can move air effectively in areas up to 22,000 square feet. To provide the same coverage, it would take 10 to 20 floor fans – and that would include the additional issues associated with these fans.
HVLS fans on their own use relatively little energy and provide a gentle, quiet breeze that provides little distraction in an environment. In fact, various studies have estimated that a 2 to 3 mph air speed creates a cooling sensation of 7 to 11°F. To put this in perspective, the effective temperature of an 83°F environment can be dropped to 72°F by adding a fan moving air at 3 mph. This means HVAC systems do not have to work as hard or – sometimes – at all, to provide cooler air within hot facilities.
Anyone who works in an industrial facility knows that maintaining a comfortable environment is a key component for success. Workers who are uncomfortably hot or cold are more prone to fatigue, error and distraction and are less productive. They are also potentially at risk for heat stress and other medical issues and are more likely to suffer from low morale.
Destratification: Bonus benefits
Although HVAC systems efficiently provide heated or cooled air to specified areas of a building, they do not optimize airflow. Because warm air rises, there might be a 20°F difference between the floor and ceiling in tall warehouses. As such, a heating system must work hard for extended periods to maintain the temperature near the floor, or at the thermostat set point, wasting precious energy and dollars.
HVLS ceiling fans mitigate the rising heat effect by gently moving the warm air near the ceiling back down toward the floor where it is needed. The air reaches the floor below the fan where it then moves horizontally a few feet above the floor. The air eventually rises to the ceiling where it is cycled downward again. This mixing effect, known as destratification, creates a much more uniform air temperature with perhaps a single degree difference from floor to ceiling. Facilities equipped with HVLS fans lower the burden on the heating system, reduce energy consumption and save money.
Networking HVLS fans & BMS connection
While a single HVLS fan can benefit an area in excess of 20,000 square feet, some facilities employ multiple fans to enhance their environmental control in specific areas. In facilities that have ambient sunlight or temperature-affecting operations (such as loading docks) in one part of the building, but not another, the fan speed, timing and other settings may need to vary by location, which creates a maintenance challenge. Fortunately, the most advanced HVLS fans can be linked into networks of up to 18 fans and run off of a single controller. That controller allows for independent speed adjustments, scheduled start/stop times and the ability to start/stop based on preset temperature settings – a feature that can be very important in operations such as medicine, produce, cheese or wine storage.
An optional Ethernet port allows the system to be accessed via a remote device so the fans can be controlled via a smartphone or other mobile device. Additionally, they can be programmed into a BMS and connected to other infrastructure equipment such as exhaust fans. A “fire stop” option is also available, in which the BMS will automatically turn off the HVLS fans and activate sprinklers in the event of a fire.
There are many factors to consider when deciding how and when to use HVLS fans. They include obstructions such as pallet racks, machinery and product staging; personnel work areas; and overall building layout. Larger diameter fans will move air further down rack aisles and over obstructions. Smaller diameter fans can be most effective in specific work areas, or where installation space is limited.
Fan suppliers can help configure an array of fans, determining the number, size and locations that provide the maximum benefit for the investment. They can also offer installation where on-site resources are not available. While the basic concept is similar across all HVLS fan manufacturers, fan design and performance are key factors to consider. There are significant differences between manufacturers, including the shape and number of blades, blade tilt, hub construction, blade-to-hub connection and safety features. The performance of different designs will vary in the uniformity of air movement directly below the fan, as well as the height and reach of air movement outward from the fan’s diameter.
Other important considerations include ease of installation, fan controls, local representative support, trial program availability and warranties.
Make HVAC better with HVLS
Proper airflow in a facility will keep the building and the people in it healthier. HVLS fans provide a practical and affordable solution to this air movement challenge in processing plants. Working in conjunction with HVAC systems, HVLS fans can help control energy costs, boost productivity and increase employee comfort.
Author’s note: The information herein is provided as a general reference regarding the use of the applicable product(s) in specific applications. This information is provided without warranty. It is your responsibility to ensure that you are using all mentioned products properly in your specific application and in accordance with all laws and regulations.
Andy Olson is a marketing manager for Rite-Hite, a global manufacturer of loading dock equipment, HVLS fans, industrial doors, safety barriers, fabric curtain walls and other industrial products designed to improve safety, security, productivity, energy consumption and environmental control.