Continuing our summer articles about lifestyle and general interest, the tutor discusses the power usage of a few devices in the home.  While these matters seldom come up during tutoring, it might be surprising more people don’t ask….

If you look back over my posts from this summer, you’ll find energy has been a theme. I’ve talked about electric cars vs gas ones, I’ve discussed electricity vs gas and diesel, I’ve talked about different units for measuring power, etc.

To someone gaining interest about the general topic of energy, an inevitable question is, “What is the energy use of a given device in my home? What does it cost to run?”

I’ve chosen a couple of devices pursuant to this discussion: my little laptop computer (which uses low power), and my wife’s hairdryer (which uses much more power).

The power supply attached to the laptop says 65W, which is 0.065kW. Therefore, running it for an hour uses 0.065kWh. BC Hydro, which is the electrical utility here, has a stepped rate: over a two month period, you are billed as follows:

For the first 1350kWh you use, the rate is 7.52 cents/kWh.

Usage above 1350kWh is billed at 11.27 cents/kWh.

Assuming I’m within my first 1350kWh this billing cycle, running my laptop for an hour will cost (0.065)(7.52)=0.4888 cents: about half a cent. Running the computer non-stop for 30 days will cost about $3.50. It’s only on about 4 to 8 hours per day; let’s call it 6 hours. Then the monthly cost is about 90 cents. BC Hydro’s billing cycle is two months, leading to $1.80 on the bill due to laptop use.

Now, let’s check out the hairdryer. It uses a whopping 1875W, or 1.875kW. Using it for an hour costs 14.1 cents. (This assumes, once again, I’m within the first 1350kWh.) Using it non-stop for 30 days would cost about $101.50. I’d say my wife actually does use it about 4 hours per month; for that, we’re on the hook for about 56 cents: $1.12 for a two-month period.

With a bill of $1.80 +$1.12=$2.92 for the laptop and hairdryer, one starts to get a picture of where the money is going. Note the computer, while it uses only about 1/29 the power of the hairdryer, actually costs more to run per month because of usage habits.

For more about household energy consumption, and the divergent topics to which it might lead, please come visit again:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.