Questione giuridica chiave
Whether the cantonally inferred requirement of a construction permit from the DAEL letter of 22 May 2000 was arbitrary.
Decisione estratta
No. The letter could be understood as a change in administrative practice requiring a regular permit procedure, not as withdrawal of an earlier permit.
Motivazione estratta
The installations had originally been allowed without a permit, but the legal context changed with the ORNI. The cantonal court could therefore read the letter as a request to submit the project to a permit procedure; this was not an insupportable factual inference.