Ceiling fans are considered the most effective of these types of fans, because they effectively circulate the air in a room to create a draft throughout the room. Ceiling fans can help improve comfort year round. In the summer, operate the ceiling fan in a counterclockwise direction. In the winter reverse the direction of the ceiling fan to operate clockwise and set on a low speed to move warm air from the ceiling to the living levels of the space. And be certain to turn off ceiling fans when you leave a room.
If you use air conditioning to cool your home, a ceiling fan will allow you to raise the thermostat setting about 4°F with no reduction in comfort. In temperate climates, or during moderately hot weather, ceiling fans may allow you to avoid using your air conditioner altogether. Install a fan in each room that needs to be cooled during hot weather.
Ceiling fans are only appropriate in rooms with ceilings at least eight feet high. Fans work best when the blades are 7 to 9 feet above the floor and 10 to 12 inches below the ceiling. Fans should be installed so their blades are no closer than 8 inches from the ceiling and 18 inches from the walls.
Larger ceiling fans can move more air than smaller fans. A 36- or 44-inch diameter fan will cool rooms up to 225 square feet, while fans that are 52 inches or more should be used in larger rooms. Multiple fans work best in rooms longer than 18 feet. Small- and medium-sized fans will provide efficient cooling in a 4- to 6-foot diameter area, while larger fans are effective up to 10 feet.
A larger blade will also provide comparable cooling at a lower velocity than a smaller blade. This may be important in areas where loose papers or other objects will be disturbed by a strong breeze. The fan should also be fitted to the aesthetics of the room—a large fan may appear overpowering in a small room.
A more expensive fan that operates quietly and smoothly will probably offer more trouble-free service than cheaper units. Check the noise ratings, and, if possible, listen to your fan in operation before you buy it.
When buying ceiling fans, look for the ENERGY STAR® label. Ceiling fans that are Energy Star certified are up to 40% more efficient, on average, than conventional models.
Description
Over 70% of American households now have ceiling fans (EIA 2020). Sales to do-it-yourselfers as well as contractors account for a brisk and growing business at home improvement centers. It is not uncommon for builders to install ceiling fans in nearly every bedroom and living area of many new homes (Figure 1).
Figure 1. Ceiling fans, such as the one installed in this bedroom, are increasingly common due to the enhanced comfort they provide. (Courtesy of BPC Greenbuilders)Ceiling fans are electrically powered, ceiling-mounted fans that create air movement which can encourage evaporation and make people feel cooler. Research has shown that, during warm weather, the thermostat can be raised as much as 4°F with no noticeable reduction in comfort if a ceiling fan or other source of air flow is present (U.S. DOE. Fans for Cooling). See the guide “Passive and Low-Energy Cooling” for more information on the cooling effect of airflow from fans as well as strategies for operating ceiling fans as part of a low-energy cooling approach.
Ceiling fans can supplement traditional HVAC systems but cannot duplicate the wide range of functions HVAC systems perform. While they can circulate the air, they cannot heat, cool, filter or dehumidify it, and they do not provide ventilation.
Ceiling fans can be installed in rooms with ceilings that are at least eight feet high. For optimal airflow, they work best when the blades are 7 to 9 feet above the floor and 8 to 10 inches below the ceiling. They should be installed so their blades are no closer than 6 inches from the ceiling and 18 inches from the walls.
When purchasing ceiling fans, homeowners should consider ENERGY STAR certified models. Fans that earn the ENERGY STAR label use advanced technologies to move air 20% more efficiently, on average, than standard models. In addition, ENERGY STAR certified ceiling fan/light combination units are 60% more efficient than standard units. Energy-efficient motors, advanced blade designs, fan optimization, efficient lighting, and modern controls are some of the technologies separating ENERGY STAR certified models from standard fans. Installers should use energy-efficient light kits on fans that specify lighting. “Smart” controls can also improve performance and provide additional comfort and convenience to occupants.
The following components and factors all affect ceiling fan performance.
ENERGY STAR Rating
To simplify the selection process, select an ENERGY STAR-rated ceiling fan, which must meet several performance criteria to qualify for the ENERGY STAR designation. If the home-owner chooses a fan that is not ENERGY STAR rated, review the manufacturers’ performance data and select one that has a high airflow efficiency-to-low watt ratio. This number can be manually input into energy simulation software, such as Energy Gauge, RemRate, etc., to determine the impact of the actual chosen fan in lieu of a default number (i.e., average). The airflow efficiency is the ratio of airflow divided by power at a specific residential ceiling fan setting (low, medium, high, etc.) expressed in cubic feet per minute/watt (CFM/watt). Most software allows manual input of this data, and for typical use the “medium” value is recommended.
Lighting
It is important to also ensure that optional light kits on ceiling fans are ENERGY STAR rated or meet efficiency goals. About 80% of the possible savings from a more efficient ceiling fan are due to more efficient lighting. New fans with lights installed should contain ENERGY STAR-labeled LED lighting. ENERGY STAR-labeled lighting, in most cases, will reduce a fan’s total lighting energy use by 60% to 80% compared to incandescent bulbs and will lessen the need to change light bulbs as often.
Motor
Basically, there are two types of ceiling fan motors: those with sealed and lubricated ball bearings and those with bearings that rotate in an oil bath. Lubrication provides smooth operation and contributes to the longevity of the motor. Motors with sealed bearings require little or no maintenance whereas motors with oil baths need occasional service, such as adding oil. High-efficiency fans use permanent magnet motors and are 3 to 5 times as efficient as standard ceiling fan motors. Fans with these efficient motors tend to be more expensive, but they draw 9 watts or less at medium speed as opposed to 30 to 40 watts for a standard ceiling fan motor.
Motor Grade
Motor Housing
The housing is the decorative body of the fan that encloses the fan motor. Fans that use heavier materials, such as die cast metals, tend to vibrate less for housing, provide more stability for longer down rods, and provide a good surface for high quality finishes.
Other features that ensure longevity and quiet operation include heavy-duty windings, precision engineering bearings, and shock-absorbent internal components. These features are commonly found in more expensive ceiling fan models.
Blade
Pitch is the angle of the fan's blades, and it is measured in degrees. Higher blade pitches usually move more air, which is given in cubic feet per minute, or CFM. However, blade pitch alone does not determine air movement. Other factors such as the motor design and speed, as well as blade design, material, number, and length can contribute to the amount of air movement. Higher pitch is NOT always better — some models offer a higher blade pitch to compensate for a smaller, less efficient motor.
Blades should be sealed from moisture to prevent warping, bubbling, or peeling. Some manufacturers offer special coatings on metal finishes to prevent scratches or tarnishing. High-quality blades are weighed and balanced prior to shipment and come in factory-matched sets. For this reason, they cannot be switched out with other fan blades. For flexibility in design, a number of manufacturers offer a variety of blade styles and finishes for a particular fan. However, changing the blade style could affect the performance of the fan.
Controls
Most residential ceiling fans (and all ENERGY STAR-qualified fans) feature the ability to reverse the motor and airflow direction, allowing you to operate the fan year-round. This control is usually found on the fan's switch housing, just below the blades. In the winter, reverse the motor and operate the ceiling fan at low speed in the clockwise direction. This produces a gentle updraft, which forces warm air near the ceiling down into the occupied space. Remember to adjust your thermostat when using your ceiling fan — additional energy and dollar savings could be realized with this simple step.
Smart/Remote Controls
Conventional fans use pull-chains or rotary wall switches, which are often unintentionally left on even when no one is home. A ceiling fan can only improve comfort if someone is there to feel its air motion. Some ceiling fan models come equipped with smart controls that can increase the energy savings and comfort potential of the fan. A 360-degree infrared motion sensor automatically activates the fan when anyone enters a room and turns the fan off when occupants have left the room. There are also smart controls (Figure 2) that can be easily installed into existing fan canopies. These controllers can be used to adjust fan speed, lights, and light dimming. These functions can be controlled wirelessly via a handheld remote controller or wall keypad. However, some smart controls may not be compatible with fans that have remote controls built into the motor.
Sizing and Clearance
Choosing the right size fan is the first step to optimizing air distribution. Ceiling fan blade-spans range from 29 to 54 inches – the most popular being the 52-inch model. To determine which size you need, measure the room where the ceiling fan will be installed and follow these guidelines from the American Lighting Association.
Table 1. Ceiling Fan Size Recommendations Based on Room Size (Source: American Lighting Association)
Room Dimensions Suggested Fan Size Up to 75 ft2 29 - 36" 76 - 144 ft2 36 - 42" 144 - 225 ft2 44" 225 - 400 ft2 50 - 54"For maximum performance, ceiling fans should be installed, or mounted, in the middle of the room; they should be at least 7 feet above the floor, 18 inches from the walls, and 6 inches from the ceiling. The report Fans to Reduce Cooling Costs in the Southeast by the Florida Solar Energy Center (FSEC) shows that circulation increases when the blade-to-ceiling clearance increases. Six inches is a bare minimum because fan performance drops sharply when the blade-to-ceiling clearance is less. FSEC tests also show that “ceiling hugger” fans provide 40% less air flow than standard ceiling fans, even when a 6 inch clearance is maintained. Thus, standard ceiling fans with an 8 to 10 inch blade-to-ceiling clearance are recommended. If ceiling height allows, install the fan 8 to 9 feet above the floor for optimal airflow.
Larger ceiling fans can move more air than smaller fans. Small- and medium-sized fans will provide efficient cooling in a 4- to 6-foot diameter area, while larger fans are effective up to 10 feet. Fans with larger blades can also provide comparable cooling at a lower velocity than those with smaller blades. This may be important in areas where loose papers or other objects will be disturbed by a strong breeze. Multiple fans work best in rooms longer than 18 feet.
Mounting System
The ceiling fan mounting system is an important consideration during the selection process. There are four common mounts for ceiling fans.