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effective way of mixing the air in a stratified space is to push the hot air down to the occupant level. This allows for complete mixing of the air in the space while decreasing both heat loss through the building walls and roof, and building energy consumption. To avoid causing a draft, fans need to be run slowly so that air speed at the occupant level does not exceed 40 feet per minute (12 m/min).
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In the late 1990s, William
Fairbank, a professor at the University of California at Riverside, and Walter K. Boyd, founder of MacroAir Technologies, invented and patented a new type of circulator fan, first called a High-Volume, Large-Diameter (HVLD) fan. This type of fan was originally developed for
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Larger diameter fans can move more air than smaller fans at the same speed. A turbulent, high velocity air jet dissipates very quickly. A large column of air, however, "travels" farther than a small one due to the friction between moving air and stationary air, which occurs at the periphery of the
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The current version, AMCA 230–12, reintroduced airflow rate with a revised equation, and new efficiency metrics. The official scope of the standard was limited to ceiling fans under 6 feet (1.8 m) in diameter. Therefore, the current standard does not apply to HVLS fans. A new version of the
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AMCA 230 establishes uniform methods of laboratory testing for air circulating fans in order to determine performance in terms of thrust for rating, certification or guarantee purposes. The 1999 version described a method to determine the thrust developed and used a simple equation to convert the
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Unlike air conditioners, which cool rooms, fans cool people. Ceiling fans increase air speed at the occupant level, which facilitates more efficient heat rejection, cooling the occupant, rather than the space. Elevated air speed increases the rate of convective and evaporative heat loss from the
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When the down column of air from an HVLS fan reaches the floor, the air turns in the horizontal direction away from the column in all directions. The air flowing outward is called the "horizontal floor jet." Since the height of the floor jet is determined by the diameter of the column of air, a
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Under ideal conditions, an 8-foot-diameter (2.4 m) fan produces a floor jet of air approximately 36 inches (910 mm) deep. A 24-foot-diameter (7.3 m) fan produces a floor jet 108 inches (2,700 mm) deep, tall enough to engulf a human standing on the floor or a cow, its initial
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HVLS fans work on the principle that cool moving air breaks up the moisture-saturated boundary layer surrounding the body and accelerates evaporation to produce a cooling effect. Ceiling fans produce a column of air as they turn. This column of air moves down and out along the floor. Called a
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Hot air is less dense than cold air, which causes hot air to naturally rise to the ceiling level through a process called convection. In still air, layers of constant temperature form, the coldest at the bottom and the warmest at the top. This is called stratification. The most efficient and
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Air movement can have a significant influence on human thermal comfort. Wind chill in cold conditions is considered detrimental, but air movement in neutral to warm environments is considered beneficial. This is because normally under conditions with air temperatures above about 74 °F
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can prevent heat stress, increase worker comfort and the productivity of both workers and livestock. HVLS fans are also used in commercial spaces, where air conditioning is more common, but increased air movement from ceiling fans can cost-effectively augment occupant comfort or prevent
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horizontal floor jet, this deep wall of horizontal moving air is relative to the diameter of a fan, and to a lesser degree, the speed of a fan. Once the floor jet reaches its potential, it migrates outward until it meets a side wall or other vertical surface.
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The power to drive a fan increases roughly with the cube of the average air speed through the fan. A commercial fan delivering air at 20 miles per hour (mph) requires about 64 times as much power as a similar sized fan delivering air at five mph.
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measured thrust to airflow. During the periodic review process, it was determined that the calculated airflow was too high; therefore this version no longer artificially calculates airflow, but leaves the measured performance in units of thrust.
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Commercial HVLS fans differ from residential ceiling fans with regard to diameter, rotational speed, and performance. While some fans use contemporary blades to move air, other methods are being used to make it more efficient such as using
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The perimeter of an air column varies directly with column diameter. While the cross-sectional area varies with the square of the diameter, the large column has proportionately fewer peripheries, and therefore less
229:. The air column from a 3-foot-diameter (0.91 m) fan, therefore, has more than six times as much friction interface per volume of air moved as does the air column from a 20-foot-diameter (6.1 m) fan.
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Airspeed, combined with fan "effectiveness," means that when the objective is to cool people or animals, very large, low-speed commercial fans are more efficient and effective than small high-speed fans.
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ISO 7730:2005 Ergonomics of the thermal environment -- Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria
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is often cost prohibitive or impractical, and is usually only used for refrigerated warehouses or the manufacture of refrigerated or frozen foods. Fans installed in spaces like
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although some are pole mounted. HVLS fans move slowly and distribute large amounts of air at low rotational speed– hence the name "high volume, low speed."
543:"ANSI/AMCA Standard 230-12: Laboratory Methods of Testing Air Circulating Fans for Rating and Certification. 2010. Arlington Heights, IL"
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Typical applications for HVLS fans fall into two classifications—industrial and commercial. In industrial applications,
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ASHRAE 55-2013 Standard 55-2013 -- Thermal
Environmental Conditions for Human Occupancy (ANSI Approved)
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agricultural applications, so early research focused on the benefits of HVLS fans on dairy production.
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body, thus making the occupant feel cooler without changing the dry bulb temperature of the air.
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Smaller high-speed fans of equivalent displacement are incapable of producing the same effect.
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larger diameter fan naturally produces a larger air column and thus a higher floor jet.
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C), the body needs to lose heat in order to maintain a constant internal temperature.
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Standard 230 sets uniform testing procedures for determining ceiling fan performance.
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606:"Measurement of Flow Characteristics of a Ceiling Fan with Varying Rotational Speed"
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greater than 7 feet (2.1 m) in diameter. HVLS fans are generally
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Chiang, Hsu-Cheng; Pan, Ching-shu; Wu, Hsi-Sheng; Yang, Bing-Chwen.
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518:"HVAC for Large Spaces: The Sustainable Benefits of HVLS Fans"
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552:. Air Movement and Control Association International, Inc
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stratification. Typical commercial applications include
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640:. Energy Efficiency and Renewable Energy Clearinghouse
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573:"Thermal Comfort Enhancement by Using a Ceiling Fan"
442:"Electric Power Saving Fan Options for Cow Cooling"
83:, airport terminal buildings, fitness centers and
708:
302:"Department of Energy 10 CFR Parts 429 and 430"
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120:
631:"Cooling Your Homes With Fans and Ventilation"
611:. Proceddings of Clima 2007 WellBeing Indoors
578:. Applied Thermal Engineering. Archived from
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157:introducing citations to additional sources
571:Ho, Son; Rosario, Luis; Rahman, Muhammad.
520:. McGraw Hill Construction. Archived from
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478:"Dairies Test New Fans for Cooling Cows"
331:"U.S. Energy Information Administration"
147:Relevant discussion may be found on the
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413:"Minnesota/Wisconsin Engineering Notes"
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335:U.S. Energy Information Administration
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702:Air Movement and Control Association
638:National Renewable Energy Laboratory
264:standard is currently under review.
254:Air Movement and Control Association
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16:Large machine for producing air flow
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688:(3 ed.). 15 November 2005.
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268:Heating and cooling benefits
121:Large fans versus small fans
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311:. U.S. Department of Energy
168:"High-volume low-speed fan"
23:A High-volume low-speed fan
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485:Southern California Edison
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550:U.S. Department of Energy
248:Measuring fan performance
365:. ASHRAE. Archived from
392:"Patent number 6244821"
356:"ASHRAE Technical FAQ"
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109:development purpose.
29:high-volume low-speed
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153:improve this article
68:distribution centers
717:American inventions
727:Cooling technology
100:How HVLS fans work
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440:Schultz, Thomas.
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668:20 September
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589:20 September
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580:the original
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45:ceiling fans
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711:Categories
528:2011-06-30
363:ashrae.org
309:Energy.gov
289:References
209:April 2015
179:newspapers
56:warehouses
149:talk page
115:airfoils
77:churches
193:scholar
91:History
85:schools
64:hangars
664:. 2013
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634:(PDF)
609:(PDF)
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481:(PDF)
456:(PDF)
445:(PDF)
416:(PDF)
370:(PDF)
359:(PDF)
305:(PDF)
273:(23.3
200:JSTOR
186:books
60:barns
52:HVACR
670:2015
646:2015
617:2015
591:2015
558:2015
492:2015
464:2015
427:2015
399:2015
378:2015
342:2015
317:2015
227:drag
172:news
66:and
33:HVLS
155:by
37:fan
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27:A
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