one of my favorite things that isn't really true (but you're a cop if you disagree) is that it's impossible to say if an electric heater is efficient or not. by the normal definition it's almost 0% efficient because nearly every watt of power gets converted into heat! but by any practical definition it's almost 100% efficient because nearly every watt of power gets converted into heat.
you're left in the difficult position of having to get mad at joules that successfully get through without becoming heat. it must drive pedantic engineers nuts
