Dear Hand Dryer Expert,
I see that the Dyson Airblade hand dryer only uses .00468kW of energy per use. The unit I am looking into purchasing has a rating of 1600W. Can you explain this?
Thanks, Brian
Answer:
Brian,
Of course! Here is a basic energy calculation to help you figure electricity use for any hand dryer:
1. Write down the listed Kilowatt per use rating.
- In your example, you stated it was 1600 Watts, which means it can use 1600 watts every hour ie 1600 W/hr.
- To get to kilowatts, move the decimal point three places to the left, (ie multiply by 1,000) which represents 1.6 kilowatts per hour (1.6 kw/hr)
2. Next, find the projected dry time per use.
- The Dyson Airblade is one of the faster hand dryers and takes about 10 seconds per dry. (Here the dry time of a few of the more popular energy efficient hand dryers.)
3. Based on the dry time of the hand dryer calculate the number of uses possible per hour.
- Divide the 3,600 seconds that there are in an hour by the 10 seconds it takes to dry one set of hands using the Dyson Airblade.
- 3600 / 10 = 360 uses per hour.
4. Divide the energy usage per hour (kw) by the uses in each hour and you will get the amount of energy used in each dry.
- 1.6 kW / 360 = .0044 kW of energy per use per dry.
That’s NOT a lot of energy per dry!
Next…
5. Find your cost kilowatt hour of electricity.
- in the US $0.10 is fairly typical, but it varies, so you can check a statement from the electric company.
6. Multiply that rate by the kW per use
- $0.10 * .0044 kW = $0.00044 per dry.
- In other words, if you are averaging 10 seconds per dry with a hand dryer that uses 1600 watts of energy, (ie the Dyson Airblade) then it is costing you a remarkable 44 cents per 1000 dries.
Wow! Now you understand why hand dryers are so much less expensive than paper towels to use. Towels cost roughly 1 cent per sheet and users average something like 2.5 sheets per use. So your 44 cents displaced $2,500 in paper towels in this example.
And while the Dyson Airblade is more efficient than many other hand dryers (the popular World Dryer Model A, for example is 2300 watts with a 25 second dry) the cost savings are still pretty remarkable just by switching from paper towels to hand dryers.
Thanks, Hand Dryer Expert
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