It means they use a lot of electricity. I wouldn't say "too much" based only on the phrase in bold, but coupled with the idea that it's a problem and you can infer that it's too much
Does the expression in bold mean that the fans need too much energy to operate?
"The problem with the fans is twofold: first, they are heavily energy intensive, and, second, they are prone to breaking down."
It means they use a lot of electricity. I wouldn't say "too much" based only on the phrase in bold, but coupled with the idea that it's a problem and you can infer that it's too much
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
Thank you.