What's the real cost of running an AC or EC fan?
Depending on the size the initial cost of AC based fans is usually 10-75% less than EC based fans. But what is the operating cost of these fans? On the comparison table below you can see that even though the initial cost is less, the yearly operating cost is about 2-3 times higher. The useful life of an EC fan is also 2 times longer. The payback period is usually around 3 months or less.
Comparison table for fans 4-6 inch diameter:
Comparison table for fans 8 inch diameter:
Comparison table for fans 10-12 inch diameter:
In order to calculate your operational cost per year you're going to do 2 things:
- Calculate energy consumption per day using this formula:
E(kWh/day) = P(W) × t(h/day) / 1000(W/kW)
- Calculate energy cost using this formula:
Cost($/day) = E(kWh/day) × Cost(cent/kWh) / 100(cent/$)
Here's an example for our 10 in model (ECMF-250):
For simplicity we're going to say that the fan is running 24h/day 365days/year.
126(W) × 24(h/day) / 1000(W/kW) = 3.024(kWh/day)
Now we know that out fan consumes 3.024 kWh per day.The average cost of kW in the United States is around 16 cents
To get the cost per day we’re going to do this:
E(3.024/day) × Cost(16/kWh) / 100(cent/$) = Cost(0.48$/day)
Now, what about the whole year?
To account for it we will multiple the cost per day by 365 days
The final amount is$176.70 per year.
What about the power consumption at low speeds?
Another big disadvantage of AC fans is that even when AC motor is slowed down, its power consumption stays the same as at full speed. The excess energy fed to motor is typically wasted through heat. Whereas EC fans' power consumption is proportional to the speed.
There are many other benefits of the EC motor besides energy efficiency and directly related lower energy costs. The airflow quality will be improved and more consistent and there will be less noise. Add in additional comfort through humidity removal, and you can see there’s a lot more to be gained than just payback.
The savings are greater for the EC fan if electricity prices escalate even further, which looks more and more probable in the current climate of drought and climate change