[farias0]

A good rule of thumb, and I hope someone more knowledgeable can correct me if I'm wrong, is that stuff that generate more heat will consume more power. So hot shower, iron, curling iron, hairdryer, rice cooker, this kind of stuff. Electronics that generate minimal heat will consume minimal power in general.

[mort96]

In general, all the electricity consumed by an electrical device gets converted into heat. If your GPU uses 250W of power, it generates 250W of heat. If your whole computer draws 1kW from the wall, it generates 1kW of heat. If your little raspberry pi and its power supply together draws 15W from the wall, it generates 5W of heat. A 1500W electrical space heater converts 1500W of electricity into 1500W of heat.

So yeah, you're not wrong.

[saagarjha]

Only if it's not doing useful work.

[Gigachad]

It's just basic energy physics. Making something hot or cold is real work. Same with moving something or producing light. But light is extremely "cheap" compared to the rest. Computing data or rendering a video game isn't real work and would consume no power if it wasn't for the inefficiency of current flowing through the chip making it hot.

[atq2119]

If I remember my long ago physics classes correctly, irreversible computation inherently costs energy: you can't get its energy "consumption" down to zero because of entropy, no matter how efficient the technology. Our computer architectures are far from reversible in a physical sense. If they were, you could run programs in reverse. That said, the minimum amount of energy required is an absolutely tiny rounding error compared to the waste heat of today's technology.

[kqr]

And if the heat goes into water, it needs even more power because water is notoriously hard to heat up.

At one point I owned many appliances that leaked heat, and I think I learned to estimate how much power they drew simply by putting my hand on them and feeling how hot they were. I'm not sure I have that superpower anymore. (Obviously it was never that exact, because it depends on many other things like volume, material, isolation, etc. But you can get fairly close for common household things – between a finger and a few heads in size, surrounded by air, plastic case.)

[ballenf]

Or to put it another way -- if hot water goes down the drain (shower, clothes or dish washing, etc.), then that's another place the waste energy is going.

[firebird84]

Better down the drain then to radiate it back into your air. Then you gotta spend more energy pumping that heat outside (if you live in a hotter climate like I do).

[jhenkens]

Alternatively, use it to warm up the cold water coming into the shower (I'd guess the largest usage of hot water in a home). Warmer "cold" water mixing with the hot water means less hot water used out of the hot water heater. My understanding, placing this only on the cold supply to the shower is it'll only impact your showers. https://ecodrain.com/en/

[thow-58d4e8b]

Correct, and the difference is not even close - anything to do with temperature manipulation consumes orders of magnitude more. Literally, not figuratively

The laptop I'm writing this on consumes around 10W. Kettle 2100W

Making one coffee in the morning consumes enough electricity to power the laptop for the whole workday

The idle power consumption of my home is dominated by the fridge and freezer (around 150W combined). Idle mode of any other devices is a rounding error