> The negative externalities are interesting though They're not interesting, because they're absolutely negligible. You're moving heat that was outside, back o

> The negative externalities are interesting though They're not interesting, because they're absolutely negligible. You're moving heat that was outside, back outside. Your house cooled the outside, and you're just undoing this insignificant amount of energy transfer. The only additional heating is from inefficiencies, which aren't so bad these days.