As a consequence of Arson crime, an investigation will take place for each incident to collate information to build a case against the fire setter. If found guilty the person will be prosecuted, fined and maybe even sentenced dependant on the crime.

Consequences of deliberate fire setting
Endangers life - a delay in attending an incident where a rescue is required could have serious consequences.
Implications to the fire setter - a fine, may affect future employment and finding accommodation.
Financial costs to the fire and rescue service
Financial costs to other emergency services
Environmental Damage