How is Energy Measured? What You Need to Know Before Paying the Bill

Electric power poles

It might seem like a straightforward question. How is energy measured? After all, what could be simpler? The power goes on; the meter spins around and somewhere in the brooding under-caverns of Energy PLC, a bill oozes its way into existence.

The segue from conception to the mailbox takes place out of sight, but still, most of us have a broad idea of how that occurs.

But asking “How is energy measured?” is a little more involved than you might at first think. There are tariffs to consider sudden price hikes, and discounts. Estimated readings rarely rub shoulders with actual consumption.

And as for that bill-friendly metric of kilowatt-hours (kWh) well, it might not be exactly what you think it is.

So, Just How Is Energy Measured?

The short answer is, well, kind of short. Energy companies use a unit of energy known as the Kilowatt. More accurately, they measure energy consumption in Kilowatt-hours. The Kilowatt-hour(kWh) is a useful way of calculating the power consumption of appliances such as a TV, games console, or toasters.

One kilowatt-hour (kWh) is one hour of using electricity at a rate of 1kW. The electricity company tallies up how many kWh you’ve consumed and then calculates your bill accordingly.

What is a kWh?

Ok, but how much is a kilowatt? And what is a watt when it’s at home, anyway?

Well, unsurprisingly, a watt is a unit of energy. Named after British engineer and inventor James Watt, it’s not, truth to be told, a tremendous amount of energy. It amounts to only 1/746 of horsepower, and for that reason, it's often measured in Kilowatts instead. One kilowatt equals 1,000 watts.

Of course, that’s still quite an abstract concept to get your head around. Saying watt is a fraction of a horsepower tends to lead to more questions such as “What is horsepower?" And that won't do. Not when the task set is to answer “How is energy measured?”

It might be helpful then, to think of it in terms of appliances.

The Appliance of Science

The air conditioner is probably the most energy-hungry appliance you have in your home. Still, since not everyone has an air conditioner, let’s take a look at the number two spot. Enter the refrigerator, stage left.

Old-style refrigerators used to gobble up a whopping 1,400 kWh per year. And let's face it, that’s an awful lot of watts. Thankfully, modern fridge-freezers are a lot more energy-efficient. A typical apartment size fridge consumes around 350 kWh per year.

That’s a big difference and is one of the reasons why manufacturers are quick to highlight such energy-saving prowess. At least, they do so whenever they try to convince you to part with your older model.

But what about those items scattered around the house that only advertise power drain in terms of wattage? How do we figure out how much they cost?

Well, that’s where the math comes in.

Lava Juice

Let’s take a lava lamp. Chosen at random for no good reason other than the fact that we know what wattage bulbs they use, this bastion of 60s illumination is something of a known quantity.

The first step is pretty simple, calculate the watts the lamp uses per day. All we need to do is multiply the wattage of the device by the number of hours you use it. Three hours seems a not unreasonable amount of time to bathe in the fuzzy illumination of melted wax globules.

That gives us a figure of 75 watt-hours per day. Of course, as already discussed, we need to convert that into kW. Dividing 75 watts by 1, 000 takes us to 0.075 kWh per day. Multiplying that figure by 30 gives us a value of 2.25 kWh per month. Yes, even in a leap year.

Now, all we need to do is figure out how much that costs.

Converting kWh to Dollars

Converting energy into its cash value sounds like alchemy, but as with the conversion of watts to kWh, it’s relatively straightforward.

There are, however, several factors at play, all of which need taking into account. The cost per kWh fluctuates over time and at any rate, differs from provider to provider.

There are fixed-rate plans, variable plans, green plans, and cancellation fees to consider. Some companies offer other incentives too. It all depends on which energy plan you go with, which in turn, depends on where you live. At any rate, shopping around is an excellent idea.

Energy flux

There are far too many energy companies for this little, “How is energy measured?” overview to cope with so let’s settle instead for some benchmark figures.

The average price as expressed in terms of cents per kWh fluctuates from state to state. For example, residents of Connecticut paid 23.35 cents per kWh in May 2019 while over in the Evergreen State, bills clocked in at only 9.81.

The differential stems partly from proximity to a fuel source and partly from topography. Hawaii’s wince-worthy rate of 33.43 best exemplifies local price differentials.

Still, the average price for Americans stood at 13.32 cents as of May 2019 for residential properties and 13.15 for commercial properties.

Lava Juice Redux

Tariff Jam

How to Cut Down on your Consumption

Light sauce

Fridge Wheezer

So there we have it. How is energy measured? Why in terms of how much you use, of course. And sure, that seems like a fairly obvious point to make, but it’s easy to see why it so often eludes us. Because so many of us take power for granted.

It’s something that we’ve used our entire life and stopping to think about where it comes from is the first step towards using it more responsibly.

Checking the wattage of an appliance is often every bit as important as the base price. Power-hungry gadgets usually cost more than their less hyperactive brethren in the long run.

So we know what to do, know what to check, and hopefully, now realize that sleeping in the comforting glow of a 75 watt-hour lamp might be good for the soul.

But it’s far from ideal for the wallet.

Do you have any thoughts to share? Sound off in the comments below.

Featured Image by Michael Schwarzenberger from Pixabay


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