That again would be a key word for the discretion of the courts, if the courts deemed that house arrest was appropriate in that situation.
You're asking for a hypothetical example. If the offender was a young person who did something very stupid and there was a great degree of remorse, if the offender was actually a minor and their guardian was taking full responsibility, if it was realized why the offence took place—maybe it's access to the Internet—and if there was an agreement with the victim's family and the offender's guardian to manage this appropriately, then in that case maybe house arrest would be an appropriate sentence. Again, it's up to the courts. They have total discretion. On “exceptional circumstances”, they would have the opportunity to say what circumstances are exceptional.