I wonder how many sleep/wake cycles would it take a day to outweigh the TCO decrease of the power bill with the TCO increase of the increased stress/amortization of the hardware, especially HDDs.
I often power it on and off 1-2 times a day, and the drives are set to spin down when not in use. The SMART data for these drives shows approximately 37,000 power on hours and 17,000 start/stop cycles. That's about 4 years 3 months of actual power on time, and about 3 power cycles per year over the past 16 years.
The spec sheet says these drives use 8W idle. So:
192 months - 51 months = 141 months of non-use
141 months * 0.730 kilohours / month = 102.93 kilohours
102.93 kilohours * 32 watts = 3293.76 kwh
Assuming 15 cents per kwh, that comes to $494 saved by shutting the drives down over the past 16 years. And I paid $232 total for the drives back in 2007.
Obviously YMMV, just thought it would be fun to calculate :)
If you're using electric resistance heat, then I suppose a running computer is kind of like processing power plus "free" heat :)
My school physics tells me that nearly everything you do with electricity at home will heat your home. Doesn't matter whether it's the baking oven, the computer or the fridge. So if you heat using electricity and live in cold climate saving energy for computers or household appliances just moves the same consumption to heating.
The big exception is heating water. That energy is typically lost to the sewer.
As long as you pay the same electricity price for your computer as for your heating, it does not make a differencd whether that's 7 or 50 cent or the 15 you estimated.
What is your spin-down time? I use the following on my server's fstab:
UUID="abcd" /data btrfs defaults,noauto,compress=zstd,x-systemd.automount,x-systemd.mount-timeout=1min,x-systemd.idle-timeout=30minI have the spin down timeout set to 20 minutes. But this is a desktop PC with intermittent usage (and different usage patterns over the years). They used to be in a RAID1+0 but now they're JBOD and I use them as scratch drives for random stuff.