Energy Labels for machines

[ElKrasso]

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Source: https://de.wikipedia.org/wiki/Watt_(Einheit)

Speed? In an abstract way, if you think of electrons.

[JanRap]

@ElKrasso, ‘speed’ doesn’t always have to be ‘distance’ over ‘time’. In music, speed is the rate at which ‘beats’ are passed. So, indeed in an abstract way, you could say ‘power’ is the rate at which ‘energy’ is passed.

[Loesje]

@lapis_lazuli

As the Joule is quite a small unit for “daily life” applications, energy is also commonly expressed in another unit, the kWh. For the 20W lightbulb one can say that if you leave it on for one hour, it has consumed 0.02 kWh.

It would however be soooo much easier if we all just talked about megajoules or whatever feasible unit, instead of the clearly confusing kWh. Which idiot ever thought of using kWhs as the consumer standard…

[BertG]

I guess it’s a kind of habit. I am really used to the kWh stuff, while something with joule always is associated with nutrition.
And just imagine, that you would get your annual electricity bill based on joules. Those numbers would give me the creeps, even using “megajoules”. You would seem to use so much more energy all of a sudden.

[lapis_lazuli]

Sure, but in many cases it could also be beneficial to use a more relevant unit to the case at hand.

Just like particle physicists measure energy in in eV instead of Joule, astronomers measure distances in lightyears or parsecs, divers or so talk about pressure levels in atmospheres or bars, etc., it may make sense when talking about the yearly energy uses of consumer devices running for hours at a time in a unit that is actually imaginable.

With the kWh, you can easily calculate the cost of using your 2000W electric kettle to boil water for tea (takes e.g. 6 minutes): 0.2 kWh of energy, which would cost 5 cents at 0.25 EUR/kWh. Using Joule this calculation would (presumably) be a bit more difficult to make.