[Kolde]

"Slaying a Vampire
Exposing any vampire to direct sunlight disorients it: It can take only a single move action or attack action and is destroyed utterly in the next round if it cannot escape."
It says nothing about the damage from the sun being fire damage. If that is how the server deals said damage through mechanics that is one thing, but RP wise, it would not matter if it was a half dragon or not.