3, 4, or 5 fan blades? Do ceiling fans with more blades give more airflow? The science behind your ceiling fan design

Recently, my family and I were looking for new ceiling fans. We would be moving into our new apartment soon, and one of our undertakings was to furnish our home with affordable ceiling fans that not only looked good, but most importantly, were also effective in moving air.

Good looking fans, yes, but how do we determine how effective are they in generating airflow? What's the science behind their design? (photo from blog.sndimg.com)

How many fan blades? How do we determine how effective these fans are in generating airflow? How do we choose our right fan? (photo from blog.sndimg.com)

The last time I went shopping for a ceiling fan – believe it or not – was when I was still a bachelor. Back then, ceiling fans were simpler, having lesser frills. But today the designs of ceiling fans have become much more varied: they look more modern, distinctive, stylish, aesthetic – and more bewildering.

So, how do we choose the right fan that can move large amounts of air? Obviously, a more powerful motor would be able to spin the fan blades faster, and the faster they spin, the more air these blades would move. But wouldn’t a faster fan also be noisier and consume more energy? And what about the number of fan blades? It is today common to find ceiling fans fitted with between four to as many seven fan blades. Some ceiling fans even have two tiers of fan blades! Intuitively, more blades would “chop” more air; thus, creating more air movement, right? But where’s the evidence?

3, 4, or 5 blades? More blades, the more the airflow? But why some fans like this Enigma fan from Fanimation have only, gulp, one blade? (photo from www.fanimation.com).

3, 4, or 5 blades? More blades, the more the airflow, right? If so, why do fans like this Enigma fan from Fanimation have only, gulp, one blade? This fan moves 5,800 CFM (cubic feet per minute) of air, making this fan comparable with other fans that have more number blades. What’s the science? (photo from www.fanimation.com).

A ceiling fan design must be such that the fan generates large amounts of air movement but yet performs its task quietly and consumes low amounts of energy. Since I was shopping for ceiling fans, I was curious to know the science behind the design of a ceiling fan. In other words, what makes an effective ceiling fan?

A ceiling fan with six blades arranged in two-tiers! Surely this fan generates massive airflow, right? We need to be skeptical because too many blades, especially one set rotating in an upper tier and the other in the lower tier might experience too much drag and create too much turbulence to give high or even a smooth airflow in the room (photo from deka.com.my).

A Deka ceiling fan with two-tiers of blades! Surely this six-blade fan model would generate massive airflow, right? Hmm…perhaps not. A fan with too many blades, especially with one set of blades rotating in the upper tier and the other in the lower tier might experience too much drag and create too much turbulence to give a high or even a smooth airflow in the room (photo from deka.com.my).

But let me however first clear one common misconception about ceiling fans. Ceiling fans, in contrast to air conditioners, do not lower air temperature or air humidity in our rooms. Ceiling fans cool us, but they do this only by increasing the air movement or airflow in the room. With increased air movement, our body sweat evaporates easier. And as our sweat evaporates, it takes away some of our body heat; thus, cooling us.

Fans do not lower room air temperature or humidity. They generate air movement which helps to remove our body sweat faster, giving us the cooling effect. Only air conditioners can lower air temperature and humidity (photo from klimatedi.by)

A common misconception: fans do not lower room air temperature or humidity. They increase air movement which helps to remove our body sweat faster, cooling us. Only air conditioners can lower room air temperature and humidity (photo from klimatedi.by).

Airflow profile

Ceiling fans do not move air in the room in a homogenous manner. Bassiouny and Korah in 2011 studied the airflow patterns in a room due to a single rotating ceiling fan. They found that airflow was the lowest at two locations: at the ceiling fan hub (i.e., fan center) and at the fan blade tip. It is somewhere between the fan center and fan blade tip that airflow was the highest.

So, if we plot the airflow velocity (speed) at various distances along the fan blade length, we would observe that the airflow generated by a ceiling fan would increase from the fan center, reach maximum at somewhere midway of the fan blade length, and then decline moving towards the fan blade tip. This change in airflow velocity which rises then falls along the fan blade length is the so-called humped airflow profile.

Humped airflow profile, where airflow velocity increases from the fan center before reaching maximum (i.e., hump) at about midway of the blade length, then decreases along the blade length (Schmidth and patterson, 2001)

All ceiling fans display the so-called humped airflow profile, where airflow velocity increases from the fan center before reaching maximum (i.e., hump) at about midway of the blade length, then decreases farther along the blade length (Schmidt and Patterson, 2001).

This is why when we stand directly under the ceiling fan center, we would feel little air movement. But shift slightly to our left or right and the airflow suddenly picks up, particularly if we stand at a distance of about midway between the fan center and the fan blade tip where airflow here is the highest.

The humped airflow profile means if we stand directly under the fan center, we would feel little airflow in contrast if we stand somewhere in the middle between the fan center and fan blade tip (photo from www.gossamerwind.com).

The humped airflow profile means if we stand directly under the fan center, we would feel little airflow in contrast if we stand somewhere in the middle between the fan center and fan blade tip, where airflow here is maximum (photo from www.gossamerwind.com).

Earlier work by Schmidt and Patterson in 2001 and Ankur and his associates in 2004 also reported similar airflow patterns.

Computer simulated airflow profile in a room with a single rotating ceiling fan. The

Computer-simulated airflow velocities (speed) in a room with a single rotating ceiling fan. The “X” marks the center of the ceiling fan. Airflow is lowest near the fan centre but increases outward up to a certain distance from the ceiling fan. Note the various “circular” airflow velocities (Bassiouny and Korah in 2011).

Studying the airflow patterns generated by a given ceiling fan is important because it allows us to understand how effective a ceiling fan design is in moving large amounts of air. And how effective a ceiling fan moves air depends on several factors, one of which is the fan blade characteristics.

Blade characteristics

Fan blade size and the number of fan blades do matter. The bigger (e.g., wider or longer) the fan blade, the more airflow the blade is able to generate. Likewise, having more blades moving through the air would generate more airflow too. However, this ignores the effect of drag or air resistance. Whenever an object moves through air, it experiences an opposing force to motion called as drag. It is this drag that slows down motion, reduces airflow, and increases energy consumption of a ceiling fan.

Consequently, there is a tradeoff between the blade size and the number of blades to have in a ceiling fan. Having fewer blades or smaller blades may reduce drag but may also generate little airflow. But increasing the blade size or fitting more blades to a fan may not necessarily generate more airflow because of the larger drag. This increased in drag would also mean a more powerful – and presumably, a more energy-hungry (and noisier)— fan motor is required. Having more blades also adds weight to the ceiling fan and again, a more powerful fan motor is required.

Falahat is one of the few researchers who reported the effect of the number of fan blades have on airflow generation. In his 2011 study, he compared the airflow generated by an axial fan fitted with between two to six fan blades. He found that maximum airflow was generated when the fan was fitted with four blades, and the blades ought to be tilted between 45 to 55 degrees to the airflow direction. In Falahat’s study, the angle of blades to the airflow direction can be regarded as the blade pitch. Blade pitch is one key factor that affects how much air a ceiling fan can move.

Falahat and his team in 2011 found that four blades was optimum and these blades should be tilted between 45 to 55 degrees, as shown in this chart (Falahat et al., 2011).

Falahat and his team in 2011 found that four blades was the optimum number of fan blades, and these blades should be tilted between 45 to 55 degrees, as shown in this chart. There was little difference between 4, 5, and 6 blades in airflow generation (Falahat et al., 2011).

Imagine the fan blades as oars of a rowboat. Rowing the boat with the oars would require the oars to be slightly tilted or slanted. If the oars were parallel (horizontal) to the surface of the water (i.e., 0 degree blade pitch), then very little movement would be created by rowing the oars. However, tilt the oars and they would push away more water and move the boat farther. Tilting the oars even more would move the boat even farther as more water would be pushed away. However, rowing the boat would become increasingly difficult if the oars are tilted to increasingly steeper angles.

Likewise, increasing the blade pitch would generate more airflow but at an increasing cost of having a more powerful fan motor to move these blades.

Falahat’s finding of 45 to 55 degrees as optimum blade pitch range is far from that found in some commercial fans. These fans often have a blade pitch no more than about 16 degrees because after which, a more powerful fan motor would be required especially for high-speed rotations.

Falahat may have used a powerful fan motor in his study: a fan that is able to spin even six blades at high speeds. Falahat’s study suggests if the fan motor is powerful enough and not treated as a factor in ceiling fan design, then the optimum number of fan blades to have is four, and these blades should be tilted between 45 to 55 degrees from vertical for maximum airflow generation.

A few ceiling fans have a curious feature where their fan blades appear to be curved or bent upward. The angle between these bent blades and the horizontal plane is called the rake angle.

Some ceiling fans such as this Kichler's Maiden model have their blades bent upward. Besides for aesthetic reasons, these bent blades can generate more airflow (photo from lumes.com).

Some ceiling fans such as this Kichler’s Maiden model have their blades bent upward. Besides for aesthetic reasons, these bent blades can help to generate more airflow (photo from lumes.com).

Bending the blades upward is not just for aesthetic reasons because varying the rake angles can produce varying amounts of airflow. Afag and his associates in 2014 experimented between 0 to 10 degrees rake angle of a ceiling fan. They discovered that 6 degrees rake angle generated the most airflow, with the additional benefit that the fan motor did not have to work any harder.

Some ceiling fans even have winglets at the tip of the fan blades, similar to the winglets found on airplane wings. The purpose of these winglets is to smoothen the flow of air around the blades by decreasing the air vortices (turbulence) at the blade tip which in turn reduces the overall drag and energy use.

Winglets at the fan blade tip help to smoothen airflow around the fan blades which would lower drag and increase airflow (photo from www.modenus.com).

These winglets at the fan blade tips help to smoothen airflow around the fan blades which would lower drag and increase airflow. Also note the slanted fan blades (photo from www.modenus.com).

The material from which the fan blades are made is also another important factor because a heavier material would add weight and would require a more powerful fan motor. Schmidt and Patterson in 2001 compared the airflow generation and energy consumption of nine ceiling fans fitted with metal, wood, and plastic fan blades. They found that ceiling fans with wooden fan blades generated the least airflow and yet consumed among the highest amount of energy. But due to the lower airflow, wooden fan blades were quieter than the rest. Schmidt and Patterson further found that ceiling fans with metal blades generated the most airflow but were also among the noisiest.

Today the ceiling fan market is inundated with many modern-looking fan, some having rather complicated designs. But I suspect some if not most of these modern-looking ceiling fans have been designed more for form over function; that is, they have been designed to look good but may not move a lot of air. Developing a ceiling fan that generates a large airflow and yet is quiet and low energy is a challenge because it requires a more thoughtful design that incorporates one or more key blade design features as previously discussed.

Some efficient ceiling fans, for instance, have fan blades that are irregularly shaped. Their blades can be sharply tapered, curved, spiraled, or twisted so that the blades do not have a constant blade width, rake angle, or blade pitch. Instead, these three properties vary along the blade length. The idea is to smoothen the so-called humped airflow profile, as mentioned earlier, so that airflow velocity remains more uniform along the blade length and at the same time, lessen the drag and noise.

But it is not easy to determine how good a ceiling fan is simply by examining the fan’s individual design features. It is the net or combined effect of these individual fan features that determines how much airflow can be generated. For instance, Falahat’s study, as previously discussed, revealed that four blades were the optimum number of blades. However, a two-blade ceiling fan could still generate more airflow than a four-blade ceiling fan. One way is to increase the blade pitch of the two-blade fan until the pitch is large enough to generate more airflow than the four-blade fan.

For instance, I recently bought a two-blade NSB Infinity fan and a four-blade Deka fan. At their respective highest speed settings, the four-blade Deka fan spins noticeably faster than the two-blade Infinity fan – but yet, the Infinity fan generates noticeably more air movement than the Deka fan. Why? This could be because the Infinity fan has a larger blade pitch than the Deka fan.

My four-bladed Deka fan has four blades and spins faster but yet generates lesser airflow than my two-bladed NSB Infinity fan. Why?

My four-blade Deka fan has more blades and spins faster but yet generates lesser airflow than my two-blade NSB Infinity fan. Why?

My NSB Infinity two-bladed ceiling fan spins slower than my other four-bladed fan, but yet the former fan generates more airflow than the latter (photo from www.nsb.com.my).

Being slower does not necessarily mean lesser airflow. Despite having only two blades, the NSB Infinity fan’s larger blade pitch could have allowed this fan to generate more airflow than the faster-spinning four-blade Deka fan (photo from www.nsb.com.my).

To tell how effective is a ceiling fan, we need to make actual measurements of how much airflow can be generated by the given ceiling fan. But as ordinary consumers, we have to rely on information provided by the fan designers on how effective are their fans.

Ceiling fan efficiency: CFM and power consumption

The two most important information we need are the amount of air movement generated (represented by the unit cubic feet per minute or simply as CFM) and the power consumption (in Watts or W) by a ceiling fan.

On average, a ceiling fan has an airflow generation of about 5,500 CFM and consumes 70 W. Dividing the airflow generation by the power consumption gives the ceiling fan’s efficiency. In this case, the average ceiling fan efficiency is 5,500 CFM / 70 W or about 79 CFM per W.

Averaged over 2,000 ceiling fans showed that the ceiling fans typically move about 5,500 CFM, consume 70 W, and have a fan efficiency of 79 CFM per W (photo from www.hansenwholesale.com).

Averaged over 2,000 ceiling fans showed that ceiling fans typically move about 5,500 CFM of air, consume 70 W, and have a fan efficiency of 79 CFM per W. A good ceiling fan is one that has 6,000 CFM or more, consumes 30 W or less, and have an efficiency of 200 CFM per W or more (photo from www.hansenwholesale.com).

Therefore, these two information pieces give us some sort of baseline upon which we can use to determine how well a given ceiling fan can move air and yet remain energy efficient. A good ceiling fan is typically those that can move 6,000 CFM or more air, have a power consumption of 30 W or less, and have a fan efficiency of 200 CFM per W or more.

Aeratron ceiling fan in an award-winning fan. Only with three blades but with careful design (such as the little winglets and twisted blades), this fan generates more than 6,000 CFM, consumes about 15 W, and have an outstanding fan efficiency of 383 CFM per W. This fan is also very quiet (photo from aeratron.org).

Aeratron ceiling fan has won awards for its very quiet operation and high energy efficiency. Only with three blades but with careful design (such as using winglets and twisted blades), this fan, at top speed, generates about 5,800 CFM, consumes about 15 W, and has an outstanding fan efficiency of 383 CFM per W (photo from aeratron.org).

Unfortunately, information about a ceiling fan’s CFM and power consumption are not always supplied or even measured by the fan designers or manufacturers. If such information are missing, it can mean that the given ceiling fan may have been designed more for looks rather than for the objectives of achieving high airflow generation, with low noise and energy consumption (i.e., a case of form over function).

There are of course many other factors beside the design of the fan blades that affect airflow, some of which are the height the ceiling fan is positioned from the ceiling, fan motor, and even the room size. However, this article discusses on a topic of fan blade design that interest me the most.

Exhale fan is a unique ceiling fan because it has no blades, so it operates very quietly. Its developers claim airflow is also more uniform within the room. Exhale fans can move about 3,200 CFM and consumes 34 W, so its fan efficiency is 94 CFM per W (photo from exhalefans.com).

Exhale fan is a unique ceiling fan because it has no blades, so it operates very quietly. Its developers claim that with Exhale fan, airflow is more uniform and gentler within the room. Exhale fans can move about 3,200 CFM, consumes 34 W, and its fan efficiency is 94 CFM per W (photo from exhalefans.com).

I have to admit that at the end of my research, I feel a little helpless. While I am now more aware on what makes an efficient ceiling fan, I am also aware that it is difficult to tell if a ceiling fan is efficient simply based on its individual design features. As mentioned earlier, these individual design features all act simultaneously to give the net outcome on whether the given ceiling fan is efficient.

Consequently, it should be a requirement that all fans be sold with information regarding the fan’s overall performance in terms of CFM and power consumption, so we would be able to make a more informed shopping decision.

All ceiling fans must be sold with information about its CFM, power consumption, and efficiency, so that we can make comparisons between fans (photo from www.energyvanguard.com).

Compulsory labelling. All ceiling fans sold in Malaysia should come with information about the fans’ performance: their CFM, power consumption, and efficiency, so that we can make intelligent comparisons between fans (photo from www.energyvanguard.com).


  1. Afaq, M.A.,Maqsood, A., Khalid Parvez, K. and Mushtaq, A.. 2014.  Study on the design improvement of an indoor
    ceiling fan.  Proceedings of 2014 11th International Bhurban Conference on Applied Sciences & Technology (IBCAST)
    Islamabad, Pakistan, 14th – 18th January, 2014, pp. 279-283.
  2. Ankur, J., Rochan, R.U., Samarth, C., Manish, S. and Sunil, K. 2004. Experimental investigation of the flow field of a ceiling fan. In: ASME Heat Transfer/Fluids Engineering Summer Conference, Charlotte, NC, USA, July 11–15, 2004, pp. 93-99.
  3. Bassiouny, R. and Korah, N.S. 2011. Studying the features of air flow induced by a room ceiling-fan. Energy and Buildings 43: 1913–1918.
  4. Falahat, A. 2011. Numerical and experimental optimization of flow coefficient in tubeaxial fan. International Journal of Multidisciplinary Sciences and Engineering, 2: 24-29.
  5. Schmidt, K. and Patterson, D.J. 2001. Performance results for a high efficiency tropical ceiling fan and comparisons with conventional fans. Renewable Energy, 22: 169–176.


  1. Hi Christopher

    Many thanks for your kind research and willingness to share!
    Have you also done the research on why some are on DC and some AC motors? Motors besides the wattage would play a part on noise and efficiency and usage right? Your ESH fan gives on only 350 CFM with a low wattage of 4W. Does it help in ventilating your room at all? Other KDK fans are promising 7000 CFM at wattage at 20W.

    • No, I have not been updating my research on ceiling fans since writing this article. More powerful motors often (but not always) mean noisy fan, and there is reason for having such a powerful motor. A powerful motor is needed, for instance, for faster rotation or to overcome heavy/inefficient fan blades. Uhm, I don’t have a ESH fan. Perhaps you were referring to my Deka fan? Deka fans often (if not always) do not give their fan performance in terms of CFM. A fan having a CFM of 350 sounds very low. Where did you get this information?

      • Thank, Christopher, for your excellent article.

        One other factor we experienced with the DEKA fans we have was that 5/7 motherboards started to malfunction within the first year. DEKA replaced them under warranty but it was obvious that they knew it was a common problem as soon as I described it over the phone.

  2. A really in depth writing bro. In choosing a fan I really go for brand without considering the design. Most of the time I will go for KDK or Panasonic. Do brand really play a big role?

    • Brands do matter as they have a reputation to maintain, but some brands are catered to certain groups of consumers. So, budget or conventional fans tend to be conventional looking but they are reliable with easy maintenance. But there are brands which have fancy looking fans but move little air or difficult to maintain because of hard to get spare parts. Some technicians are also inexperienced with these fans. So do check fan brands and see the kind of fan range they have.

  3. Before I read your article I was trying to determine , on my own , what would lend itself to making a fan more effecient? As I looked at the fans currently in my house I noticed that there wasn’t a big degree of pitch. They almost seemed flat. Now that I read your article I see that I was , indeed , on the right path. More blades, more pitch. Living in Arizona moving air is as important as cooling the air. Now I know what to look for and the questions to ask the salesman.
    Thank You , Christopher

  4. Very informative, indeed. It’s really amazing that you collected so much of info to buy a fan. My problem is that the furniture in my drawing room is put along the corners of the room where we get no air movement. I will have to now look for a good one in my local market.

  5. Thank you for a very useful information.
    I wasn’t aware you’re Malaysian until i see the compulsary labelling :p
    You wrote this article in 2014, and people is still using it as reference in 2017. Good job! 😉

      • Dear Christopher

        I have read your this article but still feel dilemma not sure which brand shall i buy for ceiling Fan. I am feel more secure and trust for branded ceiling fan (P) but a lot people said this brand got a lot of problems. For the brand (A) worry it not so lasting as (P). You has pointed out look at CFM but i cannot see it from the website. is the CFM same as RPM?
        Hope you can help me so that i can have more clear information to make right choice.
        Thank you

        • No, RPM is the number of rounds the fan blades make in a minute. Just because a fan spins fast does not always mean it moves lots of air. CFM is how much air the fan moves, so CFM is the real indicator of how effective a fan is. But CFM does not indicate the durability of a fan, only how much air it moves. If a fan has no CFM it usually means the company did not measure it (most likely scenario) or the fan has really low CFM! If a fan has high CFM, be assured that the company will proudly display, advertise, and tell you about it.

          Brand reputation is important. This includes if they give after sales service and how good it is. If the fan breaks down, do they care? Easy to get the spare parts for their fans? Sometimes a fan is so unique that, when it breaks down, you will find difficulty finding people to repair it! So, this is one issue to think about. More typical/conventional the fan, the easier to get the spare parts and more people know how to repair it.

          My suggestion is to choose a company that has a good reputation with good after sales service. Then choose their best fan. If you like designer fans, then you have several companies that sell such fans. Just be aware some fans look good but are lousy in moving air. Use the internet to find out more about certain fan models.

          Good luck!

  6. I am looking for a fan for a room 10 x 20 ft. I like the look of the “industrial” ones – three blades, no light. BUT I do not see anything in your article about the LENGTH of the blades. Industrial fan blades seem to be 56″, presumably the length of one blade, which seems pretty big for a smallish room. Does the length make any difference.
    Thanks for your reply.

  7. My compliments to you.
    Thanks a lot for such an informative article.
    Now i can decide better before buying the right fans.

  8. Thank you for producing a concise article that helps the average person to understand some of the reasons for differing performance of ceiling fans. Our family has just purchased a two year old house fitted with six ceiling fans that have wooden blades. The fans look great but are practically useless as far as moving air around. I was hoping it would just be a matter of buying a different controller that would just make them spin faster but I see now that I will have to replace them. Thanks again.

  9. Dear Chirsthoper,

    I ma renovating my condo and threes no fan points.
    Fixing a total of 5 fans.
    I am a fan of KDK fans and i would like to seek your expertise to find out which is better r to use ,the old type is with a manual regulator or the one with the remote. Which has longer life span?

    • A lot of fans nowadays are remote. I have no experience whether remote-controlled fans will last longer than those fans with manual regulators. However, I have heard any cases where fans that come with lights tend to give problems in a short period.

  10. Maybe it’s late to comment, but I wonder if these ceiling fans are working still? I am in a plan to get a new and the best ceiling fan for my farm house. waiting for your answer Christopher

  11. Hi Christopher

    Thank you for the wonderful articles and I must say I learn a lot from it. I am interested in the NSB eternity 4 foils. Based on your knowledge for this model design does it give good air flow? I try to do a comparison with infinity but not much information I can get. In addition to your write up in future maybe you can add on what kind of motor is good and reliable.

    • I have no experience with NSB eternity fan, but some NSB fans are designed more for looks and not so much for maximum airflow. This is not true for all their fans; just be aware “pretty” fans may not move a lot of air.

  12. Hi Christopher, this is one of the best articles I’ve ever read about ceiling fan. My house has a KDK 3 Blades which has been working for 33 years.
    What’s your opinion for Panasonic 3 Blades F-M15A0 vs Deka 4 Blade Designer Ceilling Fan DK60?

  13. what do you think of Fanco brands? i want something cool and i was told that more blades fan is better than the usual one but after reading your article, i am a little confused.

    What would the brand suggestion be in your opinion for a cooling power fan??

    Do you have any recommendation for Aircond too? It would be grateful if you could help me on that. I am at the moment looking at Daikin brand.

    • More blades not necessarily better as I have written. I think Fanco fans are designed to look good but not necessarily move lots of air. You need to read reviews on them on the net. You have to decide if you want good looking fans or energy efficient ones. If the latter go for 5 star fans. The same for air conditioners. Choose the right HP for your room size.

      • Thanks christopher but any recommendation from you. What i know is that NSB Infinity Fan is good. Besides that could you suggest me with any other brand that is 5* with good energy efficient?

        Also any aircond brand. HP definitely is a consideration but i want something that is good. I am just looking for honest feedback. Since you have done a good write up on fan, im sure you are able to advise on AC brands too.
        Hope to hear from u soon.

  14. Hi sir,
    I am really thank full to you for giving us such a great information on fans. I am a B-tech EEE student.we are having a subject named design and engineering to study and I got an assignment on topic fan.question is what is the science,technology and engineering behind three leafed ceiling fan.please help me sir..

  15. Hi Christopher,
    I am an electronics engineer so have zero knowledge and experience with fans. I’ve been searching for a formula to calculate the flowrate of a desktop fan (not a pc fan!). To get an idea, it is a Daewoo DCF 1706 fan (http://www.skroutz.gr/s/1722819/Daewoo-DCF-1706.html).

    Obviously, I cannot find any manufacturer specs, so I wonder if it is somehow possible to get an estimate of the flowrate of this fan.

    I can easily get the diameter of the fan, the # of blades. I can also less easily get the tilt of the blades and the RPM, but I wonder if this is enough to calculate the flowrate. Do you have some guide/research paper/formulae/ to suggest?

  16. Hi Christopher

    Great article. Very informative and useful to us now bcos we are looking at the following fans:
    a) living room – ceiling fan (considering Fanhub ACER or Lilium, Sapphire FM2626 or Deka)

    b) balcony – ceiling fan with lights (considering Deka Baby LED or Fanhub)

    c) 3 bedrooms, Dining and Kitchen – considering Deka M3 or MS16

    According the shop owner, he highly recommend Fanhub ceiling fans bcos high CFM (more than 7000) and 1yr onsite service & support in Singapore even if buy in Johor.

    Our reno themeis modern contemporary.

    Any advice and recommendations pls.

    Thanks & Rgds
    Peter & Yonah

    • Fans with more than 7000 CFM are top of the line fans, so it is important you check online if the salesman pitch is for real or not exaggerated claims. If you can’t find any data on those fans then you can regard the man’s claims as exaggerated because if the fans really move that much of air then the company will advertise that information proudly. So please check independent sources.

      My experience with ceiling fans with built-in lights are usually negative; the light or fan after a short while will develop problems, so I recommend against getting those 2-in-1 fans. Depending on how large are your rooms, you might want to get more than a fan. It is always better to have one more fan available in the room.

      • Wow… thanks for your very fast response. Will take note yr advises. Not sure but he could have mistaken CFM with RPM right?

        Reason for us considering a 2 in 1 fan cum light for balcony is bcos space and elec point constraints.

        Any comment for how good and reliable are the Fanhub, Deka and Sapphire brands?

        Thanks again. We truly appreciate yr expert advice.

        Warmest Regards
        Peter & Yonah

        • Hahaha. I am no fan expert, just someone who have read up about fans. I have not heard of those fans except for Deka which are widely available. I think their fans are simple and functional but not designed specifically to be fast. This is not to say Deka fans are bad, just be aware Deka fans are not designed specifically to be fast. They are designed to look good but affordable.

          No, CFM is not RPM. CFM means cubic feet per minute whereas RPM is rounds per minute. CFM measures how much air is moved, whereas RPM measures how many rounds the fan blades spin in a minute. You want to know the CFM not RPM if you are looking for a fan to move lots of air.

          If having another electrical outlet is not an option for your balcony then what to do? You may have to get the 2 in 1 fan, though I am not keen of such fans. Sometimes their lights are too dim. Perhaps you can get a stand fan instead. They have rather good stand fans nowadays. Just avoid getting the overhyped Dyson fans. Vordano stand fans are good though they do not oscillate.

  17. Christopher…great article!

    I just purchased and installed a Harbor Breeze Saratoga Platinum Series 60-in Fan (DC Motor) rated at 7344CFM at High (Speed 1-6).

    We sat in the family room with the fan being 8′ above us, I had it on high but did not tell my wife. I asked her what she thought and she liked it because it was quiet and she could feel the air, she asked me to put it on high so she could really see what this big fan could do, I told her it was on high and she was disappointed. I know larger fans do not spin as fast, but it sure looks slow.

    Our 52″ ceiling fan in the bedroom (same height) when on high feels like a hurricane…you can really feel the wind blowing. Yes, it’s a lot louder than the 60″ fan.

    The new fan has a high CFM, but you just can’t feel the wind…is this normal, maybe I was expecting too much? Is there a chance the motor is bad? At the lowest setting the fan spins pretty slow and does almost nothing.



    • Hi Mitch! Thanks for your visit and time to leave a comment. The Harbor fan has wooden blades, so this explains its quietness, but wooden blades don’t move as much air as steel blades (keeping every other factors the same). But the Harbor fan does have a very high CFM, so I am perplexed too why one should feel less wind than the other lower-end fan. If there’s nothing wrong with the Harbor fan, other factors like the size of your rooms could explain why this fan seems to move less air. If your family room is large, a single fan, even if it has a high CFM, may not adequately move enough air. Perhaps you could move the Harbor fan into your bedroom (where it spins quietly whilst you sleep) and install two fans in your family room. I have done this for my own house. I know my advice isn’t much, but I hope I have at least provided some helpful hints in solving your problem.

  18. Hi Christopher,
    Very informative article. Thank you.
    Do you know where I can get the Kichler’s Maiden curved blade fan? Is it available in Malaysia or Singapore?

    • No, I doubt this fan is available here or in Singapore. You can contact Kichler directly and ask if they have a local dealer here in Malaysia or if they can send it to you. However, the risk is there would no warranty or spare parts might be hard to find should the fan develop problems.

  19. Thanks for the useful information. I’ve brought a unit of NSB Ovio and Aeratron. Today received it and found out that Aeratron is using bracket holder instead of the hook type. You should highlight this in your blog about the non-common type of fan holder.

  20. Excellent place to start for a novice, really informative read as ever.I love the double fan. I have been looking at that for myself

  21. Hi Chris,
    I’m impressed with your articles.
    I have a high ceiling roof with 223fsq area thinking of fixing those HVLS fan but wondering any reliable maker besides bigass brand from singapore?

      • Hi Chris, you have most of the corners on how to choose a ceiling fan covered but you had missed out some of the important factors that I may want to add on.

        1) Certification on safety: All type of ceiling fan including decorative must be tested and certified by SIRIM. If not, in the event an accident such as fire, electrocuted due to short circuit and ceiling fan fall off from the ceiling hurting somebody, Insurance company may deny compensation!

        2) Ceiling fan Performance: Suruhanjaya Tenaga already implemented Star Rating regulation on all type of fan except those officially classified as decorative ceiling fan. In order to qualify for the Star Rating, the ceiling fan need to be tested and certified by SIRIM. So the shop owner can never cheat you.

        3) Malaysia do not use CFM to measure air volume, we are now using CMM or Cubic Meter Per Minute. 1 CFM = 0.0283 CMM

        Conclusion, look for Safety Marking or SIRIM sticker and Star Rating sticker on the ceiling fan that you are buying. By doing so, you can never be wrong.

        Note: Most of the ceiling fan sold in the market today are not SIRIM tested and certified!

  22. mr. Christopher

    I’m considering for Alpha 719/3B or viva. are they good items? requirement for 3/4 blades, dark color, not wobble, low noise, energy save and guarantee for long life *i wish*. Or, should i just go for traditional choice, KDK, for the quality proven? appreciate your advise

    • It is best to go to a shop with such display units for you to check out. I have no experience with such brands, so I cannot offer any recommendations. Read my article about fan blade design and do a picture search of those fan models to see what kind of design they have. That way, you can at least guess which fan is better in terms of moving air. Unfortunately, noise is difficult to test in the show room or we cannot tell just by looking at the fan design. All fans should not wobble. If they wobble, it means the fans were installed wrongly.

  23. Thank you so much for the information. It’s a great sharing. I am looking for fans for more new house and I am deciding whether to have pendant light in the middle with two fans at the side in my dining and living room. After reading your blog, I have no more hesitation for doing so because I love chandelier pendant light. After reading your blog, I have some ideas what fans to go for.

    May I know which outlets have more fans to offer in their showroom?

    Thank you once again Chris.

    • Thanks for your kind words. I was told that shops do not make much profit from selling ceiling fans, so not many shops display fans at their shops for you see and test. However, if you are looking for designer fans, it is better to go their website and determine who are their authorized sellers. You can then contact these sellers and ask if they have display/demo fans at their shops. But be prepared to be disappointed that even these authorized sellers do not carry demo fans, although they can order the fans for you if you decide to purchase them. Many shops that sell ceiling lights will also sell ceiling fans. You can try shops in Puchong or popular shops like Avalon and Cima lighting. But be aware not all fans are available for demo at their shops. Or you can try Kdk or Panasonic shops. Again, it is best to do your homework via the web first. Good hunting!

  24. Thank you very much Christopher for the very well written and painstakingly researched article? I was sold on the NSB Infinity fan and have ordered 2 units. The pricing is a slight premium as compared to Panasonic/KDK models but positive that it will be a better experience.

  25. Great article!
    Definitely helps to get better understanding as I am currently considering which ceiling fan to purchase..

    Thank you!

    **Kuala Lumpur, Malaysia

  26. I was researching for winglets for ceiling fans to reduce drag/power consumption when i came across your article. Learned some more knowledge today.
    Thank you for your efforts, it takes quite some time to properly research and write on such topics.

  27. For something so simple, you can write up so much scientific fact about it. Impressive. If only all blogs in the WWW is of this standard.

  28. Thanks for your blog, Chris. I found it when i was trying to work out what was a good ceiling fan for my bedroom in Sydney, Australia. I was beginning to think that a lot of the ones I was seeing were all about aesthetics rather than function, and now at least I have a better idea of what to look for.
    It was easy to read for a non-scientist, and quite fascinating.

  29. Hello,

    It is with great interest I read your article.

    I live in Australia and recently, one of the local ventilation company called VentAir started importing fans made by DEKA Malaysia under their own Ventair brands (basically a re-badged OEM product), see http://ventair.com.au/ventairproduct_categories/designerseries

    I am really quite intrigued and interested in a few of the designs from that series namely the V6, R8 and Stealth.

    I did some research and found that these fans were made by DEKA. Now being from Australia I am totally unfamiliar with the DEKA company or brand. Is it perceived as a high, mid or budget brand in Malaysia? And is their reputation for quality and reliability good?

    Would you say the V6, R8 and Stealth are good designs or is it a case of looks over substance?

    Thank you!

    • Deka fans vary widely in their price range. There are expensive as well as cheap fans. But I notice their fans are designed more for looks or for catering to the budget conscious, rather than for maximum air flow. So, it really depends on what you are looking for in a fan. A particular Deka model may look unique but if its air flow is good, it’s probably by accident rather than through some careful design.

      • Thank you for the feedback.

        Indeed the price (for their looks) seem to be very reasonable compared to other products on AU market.

        I was initially attracted by their designs. Without seeing a demo unit in action it would be difficult to judge if the airflow would be adequate.

        I will proceed with caution.

        Are they generally regarded as reliable?

        Thank you and much appreciated.

  30. Great write-up Dr. But unfortunately this kind of knowledge driven attitude is very lacking in Malaysia. I also did some research on things before purchasing it, but in the end we purchase with coin – tossing due to data unavailability.

  31. One day, just one fine day, there will be a bladeless ceiling fan, I am sure of it. Thanks for the article, great write-up.

  32. Excellent research, keep up the good work. I’m using KDK fan with remote and it makes creaky sound after a few years, really lousy. I’ll check out NSB fans, heard it is from Taiwan. Any experience with Alpha fan?
    Do you do any research on water heater ?

    • I would rate Alpha fans the same as Deka fans. NSB fans are better designed, and some of the fan models do state their air flow rates. Although many dealers sell NSB fans, they often don’t have NSB fans in stock in their showrooms or install them in the showrooms, so we can’t have a look at the fans. NSB do participate in home decoration exhibitions like the recent Homedec, so we can see some of their models in action.

      Hahaha, no research yet on water heaters. But off hand, get one with a motorized pump and has plenty of safety features against electric shock.

  33. I have question. Does ceiling profile have direct effect the the air flow?…based on 2 examples here. Ceiling fan installed at flat ceiling VS Ceiling fan installed at hole-designed ceiling.

    • I have not come across studies done on ceiling profile effects on mass air movement by ceiling fans. Nonetheless, I suspect that “hole-designed ceilings” could complicate mass air flow. Ceiling fans need to draw air in and push out air. Anything that interrupts or disrupts these air movements (such as due to highly uneven ceiling profile) might cause eddies and turbulence, causing lesser air flow.

  34. Thank you very much for this well written and informative article which has enabled me to make a better informed choice. As you mention briefly distance of the ceiling from fan is another important factor, however in this day and age of lower ceiling heights this is usually finite

    • Thank you for your feedback. I don’t understand what you mean by saying that lower ceiling heights are finite. Do you mean that houses today have lower ceiling heights? Whatever it is, placing the ceiling fans closer to us will have us feel more air movement, but of course, the ceiling fans shouldn’t be installed too low until they pose an injury risk or they make the room not aesthetically pleasing. There are carefully designed ceiling fans that hug the ceiling, so they should be installed close to the ceiling, but ceiling fans typically need about 8-10 feet away from the floor.

  35. Hi, GREAT & IMPRESSIVE scientific elaboration on the ceiling fans !

    I really want to get the NSB Fan – Infinity .

    How long already you been using it ? Do you know the country of origin of the brand manufacture?

    Awaiting your revert with many thanks.

  36. I would suggest better fix the wall fans to ceiling fans. My daughter’s teacher ear was severed by the dropping fan, least she was not killed! My hubby’s colleagues were having meeting and the ceiling fan just dropped down right in front of the small group of 5 teachers~! I never liked ceiling fan no matter how fanciful or powerful they are manufactured cos in the end of the day, it is fixed above one’s head!
    Wall fans can be as powerful as anything, this is safer to be fixed solidly on the wall.

  37. Hi, excellent analysis. I also about to look for ceiling fan. After read your blog now have a better idea to choose a ceiling fan. But most of the ceiling fan selling in Malaysia without the label info of CFM and etc. Are you using NSB Infinity ceiling fan ? How is it ? I plan to buy and put at living hall, but some people said that the air flow might not good enough. Need your opinion of this fan. Thanks

    • A large room may require more than one ceiling fan. There are some websites where you can enter the size of your room, and it will tell you the fan size and the number of fans you need. NSB fans are good: sturdy and does not wobble like Deka ceiling fans. Deka fans spin faster but ironically generates less air flow. Unfortunately, good design fans are more expensive, sometimes 2-4 times more expensive than budget fans, but you do make up for it by these expensive fans consuming less electricity, so in the long run, you save money.

  38. hi Chris,
    two tumbs up on your blog. this is the first time i sneak into your blog and i was really astonished on how extensive and how academic your postings are, even on the simple topic of choosing a ceiling fan! i have never seen a casual but very technical academic blog like this before.

    i’ll bookmark your blog and read them slowly, all of them.
    keep up the good work.

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