If you're worried about power consumption from a cost perspective, it's going to take a long time to break even from the cost of new hardware, even for a cheap pi.
If you're worried about it from an environmental perspective, it often takes more energy / resource mining / pollution to manufacture a new piece of hardware than the total amount saved from not running older hardware over a longer lifetime. Running a computer / smartphone / tablet until it doesn't work well enough for its purpose is generally better for the environment than upgrading because shiny, because it slightly reduces the demand for new hardware.
> If you're worried about power consumption from a cost perspective, it's going to take a long time to break even from the cost of new hardware, even for a cheap pi.
That depends a lot on where you live. In Germany, prices scratch 0.3€/kWh. A new Pi sets you back 60€ [0]. Assuming you save 20W and it's on 24/7, you'll break even in just above a year[1].
[0] I know it's marketed as cheaper, but you never get it for 35€ and then you still need cables and an SD card.
Sure, and it never hurts to do the math for your particular situation. Being in California I'm probably paying about the same as you per kWh. I do think 20W delta is rather optimistic, since the last time I checked a decade ago, laptops only consume 10-15W at idle, and pi's likely consume at least a few watts themselves. Laptop hardware is generally pretty good about reliably suspending to ram and resuming.
My general point is that there's a lot of externalized costs to consider depending on what you're trying to optimize for. For example, I live in a somewhat chilly area most of the year, and part of my home is electrically heated rather than by natural gas. I don't particularly care how efficient any electronics are in that part of the house (when I'm using them) because that electricity is converted into useful heat just as well as a space heater would do it.
I had a nightmare last night that my 3 year old smartphone's screen got horribly scratched enough to be a constant nuisance but not bad enough to interfere with its function, and I had to decide whether or not to give up and upgrade.
This isn't necessarily related to the discussion at hand, but it reminded me:
I got a huge crack (https://ibb.co/1mPxC6C) in my smartphone's screen right around New Year's. One of my goals was to use my phone less (less social media). The crack is a big, ~.25in black diagonal line across the screen, but the touch still works. Because it's a diagonal crack, I can still read whole text messages/emails/etc, I just have to scroll the right way.
It's now March and I still haven't fixed my screen, mostly out of laziness since I'm home all the time, but also because it's done wonders to my smartphone use. I practically don't idly scroll anymore, just because it's really annoying to do so, and I don't miss it at all. Everyone thinks I'm nuts, but I haven't read twitter in like 3 months so who's the crazy one?
I'd say, don't bother upgrading! Enjoy that the addictive quality of your smartphone is diminished.
Lol, thankfully it was just a dream and my screen is still flawless! I did stop bothering to put protective glass on it after that cracked a few months ago.
The only thing I read obsessively on my phone these days is hacker news. :-) I stopped using most social media 6 or 7 years ago.
If you're worried about it from an environmental perspective, it often takes more energy / resource mining / pollution to manufacture a new piece of hardware than the total amount saved from not running older hardware over a longer lifetime. Running a computer / smartphone / tablet until it doesn't work well enough for its purpose is generally better for the environment than upgrading because shiny, because it slightly reduces the demand for new hardware.