[spicyjpeg]

A nice side effect of people doing this is that, depending on where you live, you might be able to obtain these older, less power efficient devices for relatively cheap on the used market. Of course if you can barely afford electricity buying them is probably not a bright idea, but for someone with e.g. their own PV system it can be a great way to save some money while also reducing the amount of e-waste going to landfills.

Even better, this is not limited to large power hungry appliances. You can build a surprisingly decent gaming handheld out of an old flagship phone with the help of rooting and some hardware mods [1], basically taking advantage of the low resale value of Android devices.

[1] https://youtube.com/watch?v=px1A6XptqhQ

[bombcar]

And if you’re in an area that gets cold, waste heat isn’t so bad - in the winter.

[lkbm]

True, it's not a full loss. A heat pump can easily be 400% efficient, though, so I'd rather lean on that except in extreme cold.

Still, not a bad idea to run Folding@Home all winter.

[titzer]

IIUC you need a higher temperature source from which to pump heat, so in the winter, where do you get that temperature differential?

[jhenkens]

Thankfully, you are wrong about that! Just like you don't need a cooler source _from which to source cold_ in the summer with AC. Technology Connections has a fun (well, to me) video on how heat pumps work and are great. Literally just AC units running in reverse, thanks to having a valve.

https://www.youtube.com/watch?v=7J52mDjZzto

[extra88]

Yes, Technology Connections is a great channel and added a couple of new videos about heat pumps in the past month.

https://www.youtube.com/c/TechnologyConnections/videos

[bombcar]

At a certain temperature differential you need to source "heat" from elsewhere, which is why up north you either need a geothermal heat pump (underground piping) or you supplement with gas or electric heat.

Some very efficient pumps can work down to 0 degrees, but most start losing efficiency at 25 to 40 (Fahrenheit).

For some parts of the world, a heat pump is perfect - pump in heat in the winter and heat out in the summer, but when the outside temperature can hit -40º Fahrenheit (which is -40º Celsius), you're gonna need something else.

[outworlder]

For the overwhelming majority of the world they are perfect. Even in high latitudes, they might only reach those extremes for a few days in a year, that's when you would require a backup.

Losing efficiency is fine since they are so ridiculously efficient to begin with.

[lmt55]

This is not true, any more than your fridge needing a source of cold from which to cool itself down.

[ryankrage77]

The temperature differential is between the outside temperature and -273°C. There's still heat energy to be captured even on a cold day.

[mmcnl]

100% efficiency is rather low for heating. Heat pumps easily give you 400%. Efficiency in this case calculated as: generated energy (in heat) / electrical energy. Efficiency goes beyond 100% because heat is extracted from air or water.