There should be a different name for a Kilowatt-hour

[zkkxzd]

How many times have you seen or heard people get power and energy (kW and kWh) mixed up? I think the general public gets it wrong more often than right.

Prime example, this media quote a couple of days ago from Rewiring Australia, a non-profit advocacy group who's sole focus is electrical energy.

"Right now, a household that's got two parents and two kids probably uses about on average 30 kilowatts a day," he said.

"If you've got a typical like six kilowatt [solar] system on a typical sunny day in spring, you'll probably generate about 30 kilowatts of energy, but it'll all happen at midday."

No matter how many times I try to explain the difference to my uncle, he doesn't get it.

The problem is the units look and sound so similar. A unit for energy should obviously suggest energy rather than power, so people realise they are distinct concepts.

One solution would be to use Joules for energy (1 Wh == 3.6 kJ), or maybe express it in terms of an equivalent amount of petrol/gasoline. Either way you lose the ability to do simple calculations and conversions in your head. A better solution would be to rename the Kilowatt-hour to something that suggests energy. It could be as simple as "home-energy-unit" or similar.

Alternatively, keep "kWh" and express power differently (1 kW == 0.38 Usain Bolts).

Any ideas, and how to get such a name to catch on?

 

[hwy17]

It's a nice thought but there's no helping those people.

We couldn't even save the vast majority of car guys who still think that torque is a relevant second factor to a horsepower curve.

 

[hidiyguy]

It's like miles vs miles per hour. If you drive you get it and if you don't, maybe not until you're informed of the difference.

I personally feel kilowatt-hour is perfectly descriptive and doesn't require a convoluted fix that the uninformed still wouldn't understand.

 

[Jacob89]

It frustrates me no end that people can't get it right, but I'm not sure changing the name would be helpful.

 

[jgh]

If you seriously think you can get people to use Joules, I have a small Colossus of Rhodes to sell you.

 

[Gadwall*Drake]

Brain dead marketing departments all over the place seem to think that watt is a unit of light output. This no doubt adds to the confusion. People are dumb. Just look around.

 

[Mattb4]

Would be nice if basic electricity was taught to school children. Having to learn it out in the streets and gutters from unsavory types is a recipe for ignorance and harm. Reading, Riting, Rithmetic and Resistance.

 

[Sunny Day]

I find it strangely comforting that the fiercely anti-metric US so willingly uses kWh instead of insisting on horsepower hours or dog-pulling minutes or something random.

 

[chamilun]

bothers me literally zero. what I do love is seeing that I got 12 kwh of solar yesterday. and higher every day.

sometimes life is way easier by not being bothered by everything under the sun

 

[ricardocello]

I find it strangely comforting that the fiercely anti-metric US so willingly uses kWh instead of insisting on horsepower hours or dog-pulling minutes or something random.

We use kWh because the power companies decided to bill customers based on that.
If they had started billing using horsepower-minutes, then that is what we would be using.

Fierce anti-metric attitudes in the US are largely limited to attempts to replace common units that normal people use everyday:
inches, miles, pounds, degrees F, quarts, etc.

You can't just legislate internal measurement scales away from people.

But you can sell 2-liter soda bottles, perform PCB thermal testing in degrees C, buy M3 bolts at hardware stores, use millimeters to describe dimensions of small objects, buy a 750ml bottle of wine, and give a torque spec in N-m. Or go on a 10km run.
Only the fiercest anti-metric people will balk about those.

We build stick houses using 2x4s (inches), which are actually 1.5 x 3.5 inches.
Converting an entire industry to metric would costs billions of dollars for no benefit.

Bottom line: It is about convenience, cost, and convention more than hatred of the metric system.

 

[Sunny Day]

Bottom line: It is about convenience, cost, and convention more than hatred of the metric system.

Yeah, but those French tho…

 

[ricardocello]

Yeah, but those French tho…

I wonder why metric time measurements never took off...

Decimal time - Wikipedia

en.wikipedia.org

 

[Q-Dog]

I wonder why metric time measurements never took off...

Time cards on most movie projects I've worked on are done in 10ths of an hour. Why? No one knows. Probably makes the math easier on the accounting side, and keeps everyone else confused.

 

[SeaGal]

I know.... how about calling it a BTU - British Thermal Unit None of that metric stuff.

You could come up with a formula of it being the energy needed to raise the temperature of one pound of water by one degree Fahrenheit. Oh wait....

 

[Backyard]

We use kWh because the power companies decided to bill customers based on that.
If they had started billing using horsepower-minutes, then that is what we would be using.

Fierce anti-metric attitudes in the US are largely limited to attempts to replace common units that normal people use everyday:
inches, miles, pounds, degrees F, quarts, etc.

You can't just legislate internal measurement scales away from people.

But you can sell 2-liter soda bottles, perform PCB thermal testing in degrees C, buy M3 bolts at hardware stores, use millimeters to describe dimensions of small objects, buy a 750ml bottle of wine, and give a torque spec in N-m. Or go on a 10km run.
Only the fiercest anti-metric people will balk about those.

We build stick houses using 2x4s (inches), which are actually 1.5 x 3.5 inches.
Converting an entire industry to metric would costs billions of dollars for no benefit.

Bottom line: It is about convenience, cost, and convention more than hatred of the metric system.

Not only that, ask them how big their lumber is and you'll find that they are all based on our imperial dimensions. Just converted over to metric. Example: sheet of plywood is something like 1219x2438. Doing the math, that's 4x8. Having to remember numbers like 1219x2438 is just stupid. They are using our dimensions from the US and most don't even know it.

And in a strange twist, all our units are actually based on metric units anyways. So...

 

[wpns]

So if I've got a 52 megajoule battery, how long will that run a one kilowatt load?

There's no saving people who can't do math, can't figure out units, and can't convert between power and energy.

 

[wpns]

People are dumb. Just look around.

I'd just me and my dog in this room ATM, what are you trying to say?

 

[SeaGal]

Seriously though, I suspect the confusion is related to the 'energy' value being a 'power x time' unit. Which is the exact opposite of what non-scientific people are more familiar where the instantaneous measurement is expressed as the total amount divided by time.

e.g. speed which is measure as 'miles-per-hour' or 'metres-per-second'. Or other common measurement like an engine rotation of 'revs-per-minute' or flow rate as 'gallons-per-hour'.

 

[SeaGal]

Not only that, ask them how big their lumber is and you'll find that they are all based on our imperial dimensions. Just converted over to metric. Example: sheet of plywood is something like 1219x2438. Doing the math, that's 4x8. Having to remember numbers like 1219x2438 is just stupid. They are using our dimensions from the US and most don't even know it.

Yep... it's crazy. Since about the 1980's manufacturers have to sell products in the UK in metric units. But we measure road distances in miles, buy fuel in litres, but measure car consumption in miles-per-gallon (English gallons of course!). And us oldies still think about feet and inches!

Then.. in theory, we buy food in grams and litres... but in practice most items are sold in containers relating to their old measurements (yep 50 years later)... So we can buy milk in containers of either 568ml or 1.136litres = 1 or 2 pints... proper English pints that is, not American ones. And jam in jars of 454g = 1 pound (at least we agree on that one!).

Don't get me started on car tyres (= tires)... they are sold with measurements like 245/35x19. Where the 245 is the width of the tread in millimetres, 35 is the sidewall measurement as a percentage of the width (so 35% of 245mm). And yes, you guessed it, the 19 is the diameter of the wheel..... in inches!

 

[SparkyJJO]

I know.... how about calling it a BTU - British Thermal Unit None of that metric stuff.

You could come up with a formula of it being the energy needed to raise the temperature of one pound of water by one degree Fahrenheit. Oh wait....

We should only use ATUs here. Don't need no stinkin' British stuff here in 'murica, we cast you Brits aside over 200 years ago, so there /arms crossed

 

[ricardocello]

We should only use ATUs here. Don't need no stinkin' British stuff here in 'murica, we cast you Brits aside over 200 years ago, so there /arms crossed

Ironically (Wikipedia reference):

In a short note, Woledge notes that the actual technical term "British thermal unit" apparently originated in the United States, and was subsequently adopted in Great Britain. See Woledge, G. (30 May 1942). "History of the British Thermal Unit"

 

[SparkyJJO]

Well, that's interesting.

Maybe because the Brits are full of hot air, so we named our heat units after them

 

[SeaGal]

- so there

 

[Dagoth Ur Does Solar]

I do think it's a matter of ignorance, I don't think there's anything inherently difficult to understand about kilowatt hours, as a layman.

I find it strangely comforting that the fiercely anti-metric US so willingly uses kWh instead of insisting on horsepower hours or dog-pulling minutes or something random.

Ironically (Wikipedia reference):

In a short note, Woledge notes that the actual technical term "British thermal unit" apparently originated in the United States, and was subsequently adopted in Great Britain. See Woledge, G. (30 May 1942). "History of the British Thermal Unit"

That's it, we're changing it to American Thermal Units!

 

[Backyard]

So if I've got a 52 megajoule battery, how long will that run a one kilowatt load?

There's no saving people who can't do math, can't figure out units, and can't convert between power and energy.

Math ("maths" ) says 14.44 hours