The cost for Tauranga's $303 million civic precinct has escalated before detailed design of the project has begun.

But the Tauranga City Council commissioners are determined not to pass this cost onto the ratepayers.

The $4.5 million increase is caused by the construction cost of mass timber buildings to achieve a six-star sustainability rating and the public open space landscaping of the precinct, named Te Manawataki o Te Papa.

Half of the $303m budget will be funded through ratepayers and the rest is expected to come from asset recycling and grants.

Commission chair Anne Tolley said they wanted to include the 'sustainability enhancements” but 'restrict” what contribution the community makes, during a council meeting today.

'If the costs do go up … we have to find that money elsewhere.

'From the commission's point of view that was a part of the contract that we made with the community in advancing these plans.”

Tolley said although the $4.5m cost increase was 'small” she would like to see it brought back to the original $303m budget.

In May, the commission signed off on the precinct after community consultation through the annual and long term plans.

At Monday's meeting the commission approved moving to the detailed design and costing phase with the provision that the ratepayers' contribution doesn't exceed $151.5m.

Project partner Willis Bond presented the council with the preliminary designs for Site A of Te Manawataki o Te Papa during the meeting.

Site A is the area between Wharf Street and Hamilton Street in central Tauranga and will have connections to the waterfront through an upgraded Masonic Park.

Willis Bond director Wayne Silver project said the hybrid wooden design of the library and community hub, and the civic whare, exhibition and museum building were 'premium in cost” so the 'challenge” was to achieve cost savings in other areas.

Silver said there had been a 'significant evolution of design” for the two buildings with the six-star sustainability rating 'front and centre”.

The design for the community hub includes a glass façade that represents ponga leaves. Photo: Tauranga City Council.

The library and community hub's estimated cost is $91.5m a $3.3m increase from the design approved in May. While the museum and exhibition gallery went up to $110m a $6m rise and the cost for the civic whare rose $100,000 to $15.5m.

The library and museum both lost a storey but the buildings' footprints have changed to accommodate most of the lost space.

Silver said not building an extra level provided 'quite a significant cost saving”.

Mana whenua were part of the project since day one and the buildings reflected a mātauranga Māori design influence, said Silver.

The library and community hub will feature a glass façade representing ponga leaves that is symbolic of education for Maori and the civic whare and museum will boast a timber frontage.

The buildings were also 'curvaceous” to reflect a water theme, which was 'economically and culturally” significant, said Silver.

'The idea of water flowing from Durham Street … through to the water's edge, through to the Moana has always been very important to us and the design team.”

Tolley said it was: 'an outstanding design [and] the vision is that it will transform the heart of the city.”

Commissioner Stephen Selwood agreed: '[The] development is truly transformational for the city that will truly give Tauranga its civic heart.”

He said he was 'really pleased” with where the project had got to but there was still 'a long way” to go.

'We've still got a fair bit of money we have to identify outside, but I'm confident that we will get there just as we've got to this point and to this milestone.”

Commissioner Bill Wasley. Photo: John Borren/SunLive.

Commissioner Bill Wasley was concerned the report to council said it was 'aiming” for a six-star sustainability rating.

'Aiming for doesn't necessarily provide me with full confidence that we're going to end up in that space.”

Silver responded: 'The language was deliberate but not meant to be mealy-mouthed.”

He said it was the standard they would apply when the building plans were submitted but the standards change.

'Aiming for is a little bit of acknowledgement that we're pitching for a standard that doesn't actually exist today.

'We are confident is that based on the existing green standards we would comply.”

Commissioner Shadrach Rolleston said he was 'really pleased” with where the project had landed and it was a 'big programme” of work.

He reaffirmed the commission's view around cost.

"We did make commitments to the community through the LTPA [long term plan ammendment] particularly around cost."

The commission also approved the establishment of a new CCO that will govern and lead the delivery of Te Manawataki o Te Papa.

The CCO will draw upon a wide range of industry and commercial expertise, improve cost efficiencies and provide a structure that gives everyone confidence that the project will be delivered effectively said Selwood, in statement after the meeting.

'Our community has been waiting for such a long time for the city's heart to be restored and we are confident that this new governance structure will set this project up for success,” he said.

It is anticipated the CCO will be formally established by mid-2023.

The governance structure is expected to include a board and at least one employee experienced in delivering similar large-scale projects.

The cost of the CCO is expected to be $600,000 per year with an initial set up cost of $100,000.

Work to develop Te Manawataki o Te Papa would likely commence on-site in the second half of 2023.

The full programme of work will be completed in stages and is scheduled to be completed in 2027.

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