The provisions of sections 22a-15 to 22a-19, inclusive, shall be applicable to the unreasonable destruction of historic structures and landmarks of the state, which shall be those properties (1) listed or under consideration for listing as individual units on the National Register of Historic Places (16 USC 470a, as amended) or (2) which are a part of a district listed or under consideration for listing on said national register and which have been determined by the State Historic Preservation Review Board to contribute to the historic significance of such district. If the plaintiff in any such action cannot make a prima facie showing that the conduct of the defendant, acting alone or in combination with others, has or is likely unreasonably to destroy the public trust in such historic structures or landmarks, the court shall tax all costs for the action to the plaintiff.