The key financial instrument that needed to be changed to bed in the various proposals was the council's 2015-25 Long Term Plan.
Councillor Catherine Stewart opposed, saying there were a lot of assumptions in the business case. She looked forward to hearing the community's views. A fit-for-purpose civic administration building done in an efficient and effective manner came before any frills.
Cr Stewart said it had already cost more than $1 million for information, reports and staff time.
The business case's preferred way forward had three prongs. The first was a new civic administration building to enable the council to address its immediate office accommodation issues and to provide an efficient and effective workplace for staff and governance of the organisation.
The second was the open space around a new administration building and the third was the development of detailed business cases for a library, museum and performance venue.
A new administration building and associated open space were chosen because they were "investment ready".
None of the major elements for a new civic heart were excluded by the business case because they all contributed toward achieving the project's objectives of a more vibrant city centre, improved value for money for the community, and improved economic development.
The preferred way forward would cost $66.93 million out to 2025, or $71.62 million when adjusted for inflation.
The case for change was driven by the discovery of toxic mould in November 2014 in leaky civic centre buildings. Staff were currently housed in temporary leased accommodation in Devonport Rd.