this post was submitted on 30 Mar 2025
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So, Alec over the Technology Connections channel made an hour long video explaining the difference with kW and kWh (obviously with other stuff around it).

I'm living in northern Europe in an old house, with pretty much only electric appliances for everything. We do have a wood stove and oven, but absolute majority of our energy consumption is electricity. Roughly 24 000 kWh per year.

And, while eveything he brings up makes absolute sense, it seems like a moot point. In here absolutely everyone knows this stuff and it's all just common knowledge. Today we went into sauna and just turned a knob to fire up the 6,5kW heaters inside the stove and doing that also triggered a contactor to disengage some of the floor heating so that the thing doesn't overload the circuit. And the old house we live in pulls 3-4kW from the grid during the winter just to keep inside nice and warm. And that's with heat pumps, we have a mini-split units both on the house and in the garage. And I also have 9kW pure electric construction heater around to provide excess heat in case the cheap minisiplit in garage freezes up and needs more heat to thaw the outside unit.

And kW and kWh are still commony used measurement if you don't use electricity. Diesel or propane heaters have labels on them on how many watts they can output right next to the fuel consumption per hour and so on. So I'm just wondering if this is really any new information for anyone.

I assume here's a lot of people from the US and other countries with gas grid (which we don't really have around here), is it really so that your Joe Average can't tell the difference between 1kWh of heat produced by gas compared to electricity? I get that pricing for different power sources may differ, but it's still watt-hours coming out of the grid. Optimizing their usage may obviously be worth the effort, but it's got nothing to do with power consumption.

So, please help me understand the situation a bit more in depth.

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[–] equinox86@lemm.ee 15 points 1 week ago

After watching the video it was a bit over explained. I think he got his point across in the first 10 minutes, though I am an engineer by trade.

I appreciate his rigour in explaining and it is a good refresher on the power/energy calculations.

[–] rice@lemmy.org 15 points 1 week ago (1 children)

There's no way even 1% of people understand this in the world. Maybe 1% know of those measurements "existence" asking them what they are would get an "uhh"

[–] dustyData@lemmy.world 5 points 1 week ago (2 children)

In the world? Me and millions of other people got this info in middle school physics. Sure, maybe we mostly forgot the details by now. But it's not arcane or ancient knowledge lost to time. It's in your electricity bill every month. A quick visit to Wikipedia and I got the gist of it back. Every single physicist, engineer, and electrician got this explained again to them.

[–] sugar_in_your_tea@sh.itjust.works 1 points 1 week ago* (last edited 1 week ago) (2 children)

It’s in your electricity bill every month.

You get a comparison of electric vs natural gas flow in your energy bill? Wow!!

I think most people understand W vs kWh, at least on some level. They know things use different amounts of energy depending on what it's doing (i.e. a microwave sitting idle vs actually warming things), but they may not be comfortable estimating kWh from watts.

But that's only the first part of what OP talked about. The meat of the discussion was about energy stored in something like natural gas vs electrical energy. How exactly am I supposed to compare a gas furnace and electric AC vs an electric heat pump? Not only would I need to somehow convert therms (or whatever local unit you use for gas energy) to kWh, but I also need to understand efficiency of heat transfer for heat pumps, which will vary quite a bit based on the weather (much less effective in cold weather).

That's complicated, and many HVAC professionals here don't like heat pumps for whatever reason so they tend to think in terms of resistive heating vs gas heating, which is absolutely wrong. I want a good idea of cost difference between gas furnace + electric AC vs a heat pump, but that's not something I have easy access to.

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[–] Lumidaub@feddit.org 13 points 1 week ago

I sometimes make a conscious effort to understand electricity. For a few days, I then think I understand what's going on and then promptly I forget.

(Yes, I shall watch this video.)

[–] MangoPenguin@lemmy.blahaj.zone 12 points 1 week ago (1 children)

is it really so that your Joe Average can’t tell the difference between 1kWh of heat produced by gas compared to electricity?

Most people don't even know what a watt or watt/hour is. And have no idea how energy from gas relates to energy from electricity.

[–] boonhet@lemm.ee 6 points 1 week ago (3 children)

watt/hour

Oh yeah I've seen that used before, makes me cringe every time.

Anyway, do must people not go to high school? Or is stuff like that not part of the physics curriculum in some places?

[–] kkj@lemmy.dbzer0.com 7 points 1 week ago (1 children)

A W/h either is a big problem or will be soon.

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[–] pebbles@sh.itjust.works 4 points 1 week ago (1 children)

In my highschool physics was optional. You had multiple options for science credits and could get through without taking it.

[–] boonhet@lemm.ee 1 points 1 week ago (2 children)

Oh, in my country you have to take physics, chemistry and biology. That actually goes for middle school too. Plus geography which actually also contains geology. And math could be considered science I guess.

We have elective courses too, but all the basics are mandatory. That includes at least two foreign languages, history, our own language, literature (becomes separate subject from language in high school), music, art (including history of both), basic computer usage, shop class for boys and home ec for girls (with trades in between so us boys still got to cook and stuff, plus in elementary school everyone gets to knit and crochet IIRC). Oh and physical education unless you're disabled, in which case you either get to watch or just do something else I think.

I'm actually sure I've missed something. These are all mandatory. You can do shit like folkdance or choir for electives, or many other things depending on school. I had philosophy as one of my electives lol

I think people in some countries (the US) don't even know what they're missing out on tbh.

[–] sugar_in_your_tea@sh.itjust.works 1 points 1 week ago (3 children)

I never took chemistry, and I didn't take a real physics course until college, though we had survey courses like "physical science" throughout school.

I don't recall if we talked about watt hours specifically, but joules were certainly mentioned, though I doubt most people remember it. Most of the emphasis was on things like friction equations (given an ideal pulley and an incline with slope...), not real world things like understanding your electricity bill.

That said, I think most people intuitively understand the difference between instantaneous consumption and total consumption over a time period. They know playing games will drain their phone or laptop battery way faster than browsing the web, for example. They just tend to not stop and think about it and they simplify things in the wrong way (power rating on device), though a total energy estimate does work (e.g. when comparing refrigerators).

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[–] Septimaeus@infosec.pub 11 points 1 week ago (2 children)

He’s making a point about instantaneous versus overall energy use, which it sounds like you already understand. “Power” and “energy” are already kind of loose terms, which could make that conversation confusing IMO.

But for anyone confused by this:

For the typical energy consumer, Watts (W, kW) are relevant when considering circuit capacity. Otherwise, Watt-hours (Wh, kWh) is likely the metric you’re looking for when considering energy use.

Concretely, your coffee maker might pull 1.2 kW while in use, more than most appliances in your house, yet it probably represents a minuscule portion of your electric bill, perhaps less than 1 kWh, since it only needs to boil a small amount of water with each use.

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[–] Prok@lemmy.world 3 points 1 week ago

Full disclosure, I didn't watch the video yet, but it's likely a difference of environmental impact.

He's described in previous videos how burning gas at home is less efficient from the standpoint of a carbon footprint. I imagine this video is to help explain everything in a way that helps you come to that conclusion yourself. Teach a man to fish instead of just giving a fish and what not. So you can apply the knowledge to other things in your life

[–] werefreeatlast@lemmy.world -4 points 1 week ago (2 children)

I haven't watched it but its really simple. If you receive 1kW within 1hr and you compare that amount of power to 1kW over one second things are much different. The first is like a nice heater in a cold winter night...nice steady energy, a little bit of power. The second is like hell hole, tons of energy but still only a little bit of power. Power is the ability to do work or simply move things. Energy is the total amount of moving things regardless of the actual power used. So if you toasted a toast, that was a lot of power delivered quickly, but you could also do all that work slowly over centuries and eventually end up with the same molecular arrangement using the same amount of energy.

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