Efficient, Effective Air Movement: How to Justify HVLS Fan Systems
The ROI of large, ceiling mounted fans for warehouses and other facilities
Warehouse ceiling fans don't just cool; they de-stratify air, increase productivity, and lower utility bills & create a remarkably comfortable environment. So justification isn't simply about reducing energy costs, although that can play a large role in the process.
The first thing to realize is that high volume, low speed warehouse fans are air movement systems, not just cooling systems. They move and mix lots of air, and they do it very efficiently. As a result of the masses of air they move they are very effective in aiding cooling, heating (through heat de-stratification) and ventilation.
What you get from HVLS fans
HVLS (high volume, low speed) fans result in productivity increases (productivity is doing more with fewer resources which is a green concept), especially with a comfortable and healthy work/living environment. Their gentle airflow concept helps keep workers noticeably more comfortable. They are also very quiet systems, as opposed to the noise of multiple floor fans.
HVLS fan blades are typically 8′ to 24′ in diameter to move large volumes of air at very low speeds. This creates a gentle, but signficant air flow that has an immediate cooling effect in a hot room. A 24 foot fan can move up to 376,804 cubic feet of air per minute. Ideally, an HVLS fan will send a column of air down and out 360° towards the walls, back up the ceiling and back through the fan. That pattern, known as “floor jet circulation” naturally exchanges the air in very large spaces. Exchanged air does two things: 1) It keeps fresh air constantly circulating. 2) It actually changes the molecular structure of the room to lower temperature.
Energy Cost Savings
Because they operate at low speeds, HVLS fans use a fraction of the power of conventional fans.
They're powered by about what it takes to run three light bulbs. These huge ceiling fans move as much air mass as twenty-five 48” fans that operate with basically the same size motor—in effect, they use 1/25th the energy. In fact, to run them uses as much energy as only about 3 light bulbs.
A larger air mass has much less surface area to move and therefore less surface friction, further reducing energy needed to move the air. With large masses, once the initial inertia is overcome in air movement, the air jet created creates its own momentum that needs very little energy to keep it going. High volume low speed fans replace many other air movement solutions that would often use a lot of power and energy to be effective. They reduce heating and cooling costs in facilities that use those systems, and create comfort on their own in facilities that don’t.
Cooling: Correctly implemented systems can reduce cooling costs 20%
- HVLS fans move large masses of air at the right speed for the evaporative cooling effect of 6-8 degrees cooler
- You can set your AC warmer (up to 15 degrees warmer) without compromising comfort in the facility
- Coupled with air conditioning, fans enable 6-8 degree thermostat increases with 3-5% energy reductions per degree. You will be able to run your cooling systems less frequently while still maintaining comfort
- This can eliminate costly ducting (and related resources needed to build and install)
What if HVAC isn't viable? There are many scenarios where it cannot be implemented at all.
- In un-insulated buildings and those with large open doors (think dock/shipping doors, and/or open-sides.
- Where operations produce smoke or fumes requiring continuous ventilation.
- In large, sparsely populated warehouses where A/C would be wasteful.
- Where the dehydrating effect of A/C is undesirable.
- Where the installation of A/C would disrupt operations.
- Anywhere the costs of A/C are prohibitive or irrecoverable.
- For even air distribution in buildings with conventional evaporative coolers
Heating Appliations: similar savings
- For heat de-stratification: Expect 20% more in heat savings (and potentially more in most applications)
- Industry rule of thumb is about a 3-5% savings for every degree of thermostat reduction. Fan use doesn’t cause thermostat reduction; it causes less frequent heater cycling
- And high roof facilities, usually with their blasting heaters in the ceilings trying to blow the hot air which naturally rises, often have a 15-degree differential or more from floor to ceiling, HVLS fans even out these temperature gradients, resulting in the equivalent sensation of thermostat reduction
- HVLS fans mix bad air, including humid air that can cause damage to objects and food products, so they reduce damage and waste due to unwanted moisture.
- They help eliminate birds and bugs and all the environmental damages they cause in an operation.
Return on investment
HVLS fans pay for themselves quickly. Absent these fans people are spending the money they should be using to buy them. They get more air to more places, more effectively and economically.
Fan Size & Number of Fans - how many do you need?
A 100,000 square foot distribution center or manufacturing facility with a typical layout of racking and equipment can require five to ten fans to enjoy the optimal benefits of HVLS fan systems. The key factors are location, height, size, and density of airflow obstructions. For size selection, bigger is usually better for large areas.
Size options allow for custom solutions to unique location challenges. Ceiling heights are ideally more than fifteen feet. Clearance needed above the fans should be at least three to five feet for best airflow; nominal clearances of blades from nearby equipment and structures are recommended.