Ceiling Fans: Cheap to Run and Help Occupants Feel Comfortable
Does it make sense to use a ceiling fan to cool your home, instead of sticking with your expensive-to-run yet effective-at-cooling standard air conditioner unit?
Do ceiling fans use a lot of electricity? Compared to your Air Conditioner, heck no. Typically, ceiling fans range in size from 36 inches to 56 inches and use from 55 to 100 watts of power to spin. An average 48-inch ceiling fan will use 75 watts. Here is an energy calculator to find out how much electricity your ceiling fan uses.
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If you don’t use a room often, you likely don’t need a ceiling fan for that room. The best ceiling fans for your home will complement any decor, increase your comfort in all seasons, and possibly help you save on your energy bill, as long as you choose the most powerful fan you like that has the highest CFM rating possible in the price range you can afford.
If you find several ceiling fan models that you like, and they all have similar CFM ratings, then perhaps make the final decision by comparing the fans’ efficiency ratings — but don’t choose a smaller, more efficient fan if it won’t move enough air to do the job.
Airflow is More Important Than Efficiency
Common wisdom says that a large ceiling fan is far cheaper to run than an air conditioner if you have an older house with poor insulation. If you are comfortable with using fans to cool yourself during hot weather, then you will be able to save energy and money by leaving your AC unit off as much as possible and relying on the breeze generated by a fan.
When I Use Ceiling Fans to Cool Myself, How Much Energy Does My Ceiling Fan Use?
Ceiling fans do not cool the air in the room, remember. If you are not in the same room as the fan, then turn off the ceiling fan. The reason a room feels cooler with a fan circulating the air is because as the air moves across your skin, it evaporates water from the surface of your body, thus providing a cool effect. The temperature of the air, however, remains the same.
Standard Fan Sizing: Airflow and CFM
The amount of air a ceiling fan can move per minute is measured in cubic feet per minute, or CFM. This measurement provides a standard representation of the amount of air a fixture can effectively circulate. The rule of thumb is that you need at minimum 1 CFM per square foot of room area. For example, to determine the square footage of a room, multiply the length times the width of the room: a 5ft x 10ft bathroom = 50 sq.ft. and therefore needs a fan rated to move at least 50 CFM.
Focus on CFM for Actual Comfort and Savings
As mentioned, a fan’s Airflow (or CFM) is by far the most important detail when choosing a fan, and airflow is dependent upon the pitch of the fan’s blades.
The range of energy consumption between 52″ ceiling fans that use the least electricity and the most electricity is roughly 30 to 110 watts. At first glance, that seems like a big difference because mathematically, it means that the most energy hungry fans use more than 3 times as much electricity as the least energy consuming fans. But that isn’t the whole story, because when you look closer at the overall cost of operating either fan on an annual basis, the lack of airflow produced by the less powerful fan is not compensated by the energy savings.
Some Math to Illustrate
Assume that both of your hypothetical 52″ fans are operated 200 days a year, 8 hours a day. So 1,600 hours.
52″ Fan A uses 30 Watts (=.03 kWh)
52″ Fan B’s blades have a greater pitch and uses 110 Watts (=.110 kWh)
Cost of Electricity $.126/kWh (in Ontario on a tier payment contract, 2020)
Fan A = .03 kWh x $.126/kWh x 1,600 h = $6.05 per year
Fan B = .10 kWh x $.126/kWh x 1,600 h = $20.16 per year
Total savings of Fan A over Fan B = $14.11/year…. BUT…
By using the cheapest fan with the smallest motor that moves almost no air, instead of the “energy guzzling” fan, you save a whopping $14.11/year…and yet it is a waste of money, because Fan A fan does not have enough power to do the job and you feel uncomfortably warm all summer long. Which means a wasted $6.05/year rather than a savings of $14.11/year.
NOTE: The ubiquitous adoption of under-powered yet energy-efficient fans is also the reason many experts encourage you to skip the ceiling fan strategy and just use the AC unit.
Variables All Over the Place
You may have heard that if you use ceiling fans and raise your thermostat (you can raise it by as much as 10 degrees without compromising your level of comfort), the result will be a savings of around 10% off your cooling bill.
The problem with making energy saving calculations is that the price people pay for air conditioning varies widely based on:
- the configuration of the system,
- the efficiency of said system,
- the climate,
- and how cool the house must be in order for one to feel comfortable.
These are all variables that change dramatically from one home to the next. As a conservative estimate, at a minimum, with five adequately powered, so-called “energy guzzling” high-wattage ceiling fans in a home where the cost of air conditioning is around $150.00/month, that household should be able to save 15% of that AC cost by utilizing the five powerful ceiling fans.
Here’s the math to see the cost of operating five ceiling fans per month, at 8 hrs/day:
5 Fan A models x 30 days x 8 hrs x .03 kWh x $.126/kWh = $4.54/mo
5 Fan B models x 30 days x 8 hrs x .10 kWh x $.126/kWh = $15.12/mo
Some studies show that many people who own ceiling fans do not actually lower their thermostat and end up spending more money. These are the people who own under-powered or small ceiling fans with a low CFM rating, that do not move enough air to change their comfort level. Such fans are commonly sold at home centres for less than $150.00. In this example we are not going to change our thermostat, so we end up spending an extra $4.54/month and do not save anything on our air conditioning bill.
Now, let’s calculate how much money we can save if we raise our thermostat by 10 degrees and use the powerful fans to cool us down:
Average cost to run the air conditioner in a summer month = $150.00
Even if you still use your AC but just use it only 15% less, you have ($150 x .15) = $22.50 in savings, and run your fans on high setting for 8 hours a day for 30 days.
Subtract the cost of operating your five fans: $22.50 – $15.12 = $7.38 in savings each month. I bet you can use your AC half the time and save even more.
So when you are in the market for a ceiling fan, make sure you choose the fan that moves the most air relative to its size. The above calculations illustrate the rationale for using less efficient, more powerful ceiling fans in your home. Try the calculations for yourself.
Bottom line: Find a fan you like that has the highest CFM rating possible in the price range you can afford. If you find several ceiling fan models that you like, and they all have similar CFM ratings, only then compare the efficiency rating to help make your final decision.
If you are searching to buy a fan online and the manufacturer does not include CFM details, choose the fan with the widest blade span (52″ and up if that size physically fits. Use your judgment and measure to make sure there is at least a foot and a half distance from the blades to the wall), and choose the fan with the most blades, and/or has blades that are angled sharply to move more air. Common sense stuff.