The head of planning in Cork has strongly defended the 15-storey Prism building saying the city must evolve if it is to develop into the future.

Pat Ledwidge, the director of planning and economic development in Cork City Council, was responding to objections lodged by heritage body An Taisce who said it would ruin views of historical buildings and that a building of this height would set a precedent for others on the city centre island.

The €20 million Prism office building is to be built on the small triangular site at Clontarf Street next to the Parnell Place bus station.

Cork City Council had granted permission for the development but their decision has been appealed by An Taisce who oppose it on a number of grounds.

"The building will significantly alter the vista from Morrison's Island of the former Cork Savings Bank," An Taisce stated in their appeal.

They also said Prism would set an unfavourable precedent for construction of tall buildings on any site on the city centre island.

However, Mr Ledwidge rejected An Taisce's view stating tall buildings could be facilitated in exceptional circumstances.

"This statement appears to imply that tall buildings are, in some way, a negative presence on the city centre island and also to suggest that the city centre island is set in its current form in perpetuity," he said.

"The urban form of any city must evolve, as must the nature and use of buildings."

"If this evolution does not occur, the sustainable development of the city will not occur."

"The proposed development represents a progressive addition to Cork's urban form on a site that has been vacant for at least 40 years and is difficult to develop given its restricted nature and unusual shape. The proposal is an innovative solution to these issues," Mr Ledwidge said.

The Prism is planned by New York construction firm Tower Holdings, owned by Kevin O’Sullivan. The development has received the support of the Cork Business Association and the Cork Chamber.