Hello
I am running home automation on NUC8i3BEH with 256GB ssd and 8GB DDR4. Which is quite powerful computer - measured from power outlet it consumes 6W when idling in linux. Prior to it I had NUC 7CJYH with 4GB DDR4 and 256GB SSD - measured from outlet 4W. It really depends on RAM installed, each 8GB is 3W more.
Regarding noise and fans. Both NUCs were cooled passively (fans off) for standard linux sensor collecting workload (few dockers are running, about 1GB RAM in use ). In other words mostly idling. Of course if performance is needed fans spins up because this NUC8i3BEH with i3 8109 CPU has enough power to run even WIN11 quite comfortably,.
I would expect that with eg 12th or 13th gen intel cpus you get even bit lower idling power consumption,