Slow-moving, Fast-acting: The benefits of HVLS fans

by Katie Daniel | November 13, 2017 11:22 am

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By Vicky Broadus
The largest chain of health clubs in Canada understands the benefits of high-volume, low-speed (HVLS) overhead fans. In the last seven to eight years, Goodlife Fitness has installed them in 90 per cent of its facilities across the country, viewing the slow-moving air-circulators as an essential piece of exercise equipment.

“The fans run basically 24 hours in most places and everyone loves them,” said Lindsay Markle. Until recently, Markle was project manager with Trigon Construction Management, which—as the company’s name suggests—manages construction and renovation for Goodlife.

While HVLS fans can range in diameter from about 2159 mm (85 in.) to 7 m (24 ft), most of those installed at Goodlife facilities are in the 3-m (10-ft) range. Markle said they were brought in as an alternative to smaller industrial fans that were not doing the job. The large fans work in every season, keeping guests cool in the summer months and helping mix or ‘destratify’ the heated air that inevitably rises toward the ceiling in winter.

A place where people come for the purpose of exercising is ideally suited for HVLS fans. The constant, gentle breeze from the fans cools sweating bodies through what is known as evaporative cooling. However, almost any facility can benefit from the fans’ air circulation and energy efficiency. Since they were introduced 18 years ago, they have been installed in many kinds of industrial and commercial facilities. Further, as people become familiar with the fans’ ability to move air, they are finding the systems can replace ductwork in many places, which creates cost savings on the front end.

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Building a better, bigger fan
Since the electric fan was invented in the 1880s, people have relied on it for relief from the heat. The early technology was simple: spinning blades produced a high-velocity current of air that facilitated the evaporation of perspiration from the skin’s surface. This phenomenon made the person on the receiving end of the airflow feel cooler than the air temperature would indicate, and was much appreciated in settings such as the ‘sweatshops’ of the 19^th and 20^th centuries. However, it was clear fans that cooled one or two people were far from ideal in busy workplaces.

For more than a century, not much changed in the science of air movement; today, most fans still operate using the same principles as that very first electric fan. Then, late in the 20^th century, there was a major breakthrough in technology via HVLS fans. Unlike their high-velocity relatives, which create localized cooling with a small jet of air, HVLS fans move a lot of air through the devices’ size and rotational speed. Rather than delivering a strong gust of air over a small area, the HVLS fan produces a gentle breeze over a large area. The constant circulation guarantees all the air within a space remains at a close-to-uniform temperature—in other words, there are not layers of cool, warm, and hot air between the ceiling and the floor.

The first customers for this new kind of fan were dairy farmers, who put them in barns to keep cows comfortable and productive. Soon, however, it was recognized the fans had the same effect on people working in warehouses, distribution centres, and factories. Fast-forwarding another decade of advances in technology and design, HVLS fans can now be found everywhere from fitness centres to arenas, churches to schools, and offices to homes. The energy-efficient technology makes more sense every year as the world tries to reduce reliance on traditional power sources.

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The nuts and bolts of air movement
The use of aerodynamically designed airfoils and small, energy-efficient motors allows HVLS fans to move huge volumes of air very slowly over very large areas. How exactly does it all work? The airflow from an HVLS fan heads to the floor in a column equivalent to the fan’s diameter. When the air reaches the floor, it spreads out in all directions until it hits a wall or other large obstruction, such as warehouse racking, at which point it moves up, around, and back across the ceiling to the fan.

A single 7-m (24-ft) diameter ceiling fan can cover 1858 to 2787 m² (20,000 to 30,000 sf) from a ceiling height of up to 14 m (45 ft). In larger open spaces, multiple fans work in tandem—as the pressure front from one fan spreads out along the floor, it meets a similarly expanding jet of air coming from the other fan. These jets collide and deflect up toward the ceiling in the same way air moves when encountering a wall. The result of this is each fan behaves as though it is operating alone in a space smaller than the actual geometry of the room, thereby increasing high-speed airflow coverage within the space.

By moving a lot of air very slowly—at about 5 km/h (3 mph) or so—the HVLS fan creates quieter, less disruptive airflow that cools a far greater area than a high-velocity fan, and does it very efficiently. The average daily operating cost of a good-quality large-diameter fan is a few dollars.

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Indoor environmental quality
The frequently quoted estimate that people spend 90 per cent of their time indoors comes from a study two decades old. (For more, visit cfpub.epa.gov/roe/chapter/air/indoorair.cfm[5] or check out
www.buildinggreen.com/blog/we-spend-90-our-time-indoors-says-who[6].) Yet, it is safe to say the rise of the Internet and video games in the intervening years has not led to a significant decrease in that figure—quite possibly the opposite. That means indoor environmental quality is more important than ever, especially in regions where cold weather hangs around many months of the year. Research has linked poor indoor air quality (IAQ) to numerous illnesses, and experience shows it is linked to increased absenteeism or reduced productivity. (To read more, visit ohsonline.com/Articles/2016/10/01/Sick-Building-Syndrome.aspx[7].) The American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) provides a number of standards and guidelines addressing the issue, and all homes and other buildings must adhere to the National Building Code of Canada (NBC) as applied in their province.

As more changes are made to building design and operation in response to climate change, making buildings tighter and more efficient, it is critical to maintain good indoor environmental quality. For projects looking to earn points under the Leadership in Energy and Environmental Design (LEED) program, HVLS and other high-efficiency ceiling fans help meet Environmental Quality (EQ) Credit, Enhanced Indoor Air Quality Strategies, by efficiently distributing the heated outside air into the ‘breathing zone.’ HVLS fans can also help earn Energy and Atmosphere (EA) credits such as Optimizing Energy Performance and Thermal Comfort.

Thermal comfort and productivity
The most obvious benefit of HVLS fans is the thermal comfort they provide. Thermal comfort is defined by ANSI/ASHRAE 55, Thermal Environmental Conditions for Human Occupancy, as “that condition of mind which expresses satisfaction with the thermal environment and is assessed by subjective evaluation.”

When it is absent, achieving thermal comfort becomes the first thing on people’s minds. Many factors contribute to this consideration—the most obvious are air temperature, air speed, and humidity, but clothing and activity level also play a role. Complying with ANSI/ASHRAE 55 means 80 per cent of occupants should be satisfied with a space’s conditions.

How do HVLS fans fit in? Increased air movement from the fans makes occupants feel cooler in warm months and comfortably warm from destratification or air-mixing when the furnace is on. Just like the cows for which HVLS fans were developed, people are more productive when they are comfortable and the air is circulating, whether working on an assembly line or doing crunches at the gym.

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In workplaces, HVLS fans make it possible to eliminate floor fans and other personal cooling devices, which create clutter and tripping hazards. They improve safety by quickly drying spills and condensation, and they can even prevent condensation from forming. For instance, one metals service centre in Missouri tested drying capabilities by installing an HVLS fan over one of two neighbouring service bays. The one with the fan dried in four hours, while the other, with the same amount of water, took a day and a half. Further, thanks to the fan, less rust formed on nearby tubing.

In industrial settings without air-conditioning, the presence of HVLS fans means workers take fewer breaks because of the fans’ cooling effect. Where there is air-conditioning, the increased air movement allows thermostat setpoints to be raised without sacrificing comfort, leading to perhaps the greatest benefit of HVLS fans—energy savings.

Energy savings
The energy savings from HVLS fans can be significant. According to ANSI/ASHRAE 55, during cooling seasons, the fan speed can be increased to create a cooling effect of up to 5.6 C (10 F). The air movement allows facility managers to increase their air-conditioning setpoints by several degrees while keeping occupants comfortable. One study found energy savings of three to five per cent per degree are typical. (The study, “Extending Air Temperature Setpoints: Simulated Energy Savings and Design Considerations for New and Retrofit Buildings,” by Tyler Hoyt, Edward Arens, and Hui Zhang, can be viewed online at escholarship.org/uc/item/28x9d7xj[9].) Conversely, during heating seasons, the fan can be slowed so the air continues to mix, moving hotter air at the ceiling gently down to occupant level without causing a draft. This keeps occupants comfortable and can reduce heating costs by up to 30 per cent, as Richard Aynsley first noted in a December 2005 article in the ASHRAE Journal.

Generally speaking, the higher the ceiling, the greater the savings. There is also now technology available on some HVLS fans that automatically responds to the conditions and ensures that the temperature within a space is always comfortable and consistent from floor to ceiling. This simultaneously guarantees the greatest energy savings for the consumer.

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Less is more
Energy efficiency is not the only way HVLS fans can cut costs. Many architects and mechanical engineers have discovered air movement from the fans allows for reduced HVAC capacity and ductwork when integrated into new building designs. This opens up ceiling space as well as budgets, as spaces as diverse as office buildings and Goodlife Fitness facilities have found.

Initially, Goodlife was not looking to reduce ductwork. It installed the fans for year-round client comfort and energy efficiency, until eventually they became a signature element throughout its facilities. However, at one location in Edmonton, the company decided to try something different. As the fans do the ductwork’s job of getting cool air to the user, and are present regardless, Goodlife considered the question: why not eliminate the ductwork and see what happens? The company used a concentric step-down diffuser from the rooftop units and relied on fans to move that air around.

Doing this satisfied the design team, which liked the new, less cluttered look of the ceiling. Comfort and cost savings also improved.

“The fans have been very effective,” said Markle. “We haven’t had any complaints.”

Since that first club, Goodlife has used the same approach in several other locations.

Efficiency standards: Change is on the way
From the days of the first electric fans, manufacturers have made efficiency claims about their fans, but for more than 100 years, there was no widely accepted standard to support those claims.

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It was not until 1999 that the Air Movement and Control Association (AMCA) introduced AMCA 230-99,
Laboratory Methods of Testing Air Circulating Fans for Rating and Certification, which set more uniform requirements for testing the performance of circulating fans. However, AMCA 230-99 did not account for the HVLS fans invented around the same time. The main issue was the standard’s requirement the ceiling height of the test chamber be three times the diameter of the fan—for a 7-m (24-ft) industrial fan, this would require a testing facility with a 22-m (72-ft) high ceiling.

The emerging HVLS fan industry found itself where the residential ceiling fan industry as a whole had been 100 years before—without a practical standard for measuring performance. Therefore, manufacturers used numerous rating methods and test conditions (often of their own making), or modifications of existing standards, to measure the efficiency and performance of large fans.

In 2015, this situation was corrected. ANSI/AMCA 230-15 provided a means for determining and expressing ceiling fan efficiency and efficacy for both standard and HVLS fans.

Earlier this year, for the first time, the U.S. Department of Energy (DOE) also mandated rules requiring a uniform set of test procedures for measuring HVLS fan performance. These rules—which will likely be coming to Canada within a few years per an agreement by the Regulation Co-operation Council—mean every manufacturer must test its fans in the same way, giving customers the ability to make apples-to-apples performance comparisons between the products based on power and airflow.

The basis of the testing is a slightly modified version of AMCA 230-15, not drastically changed from earlier updates of AMCA 230. Fan companies that fail to use the prescribed test procedures or that publish efficiency data that does not come from those procedures will be subject to fines.

Conclusion
HVLS fans were virtually unheard of 20 years ago. Now the world has discovered their many benefits, from comfort and efficiency to safer, more productive workspaces, and they are being installed every day across the globe. With new rules in place, the industry is set to enter an exciting new phase marked by greater transparency and consumer confidence. This can only lead to even more spaces being outfitted with and reaping the benefits of HVLS fans

Vicky Broadus has a master’s degree and 15 years of journalism experience. She writes for Big Ass Solutions, a manufacturer of high-volume, low-speed (HVLS) and other fans. She can be reached via e-mail at vicky.broadus@bigasssolutions.com[12].

 

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