About 650 staff from three Hamilton ACC sites will work from the new building once it opens in 2022.

Iwi-owned company Tainui Group Holdings (TGH) has announced plans to develop a $50 million complex in Hamilton's CBD.

The four-storey building would become a new hub for ACC's staff, consolidating 650 Hamilton staff from across the city.

The complex, due to be completed by the end of 2022, will be built on a section of settlement land on the corner of Collingwood and Tristam streets.

It's a development bound to bring more "vibrancy" to the CBD, Hamilton's Mayor says.

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MARK TAYLOR/STUFF Tainui Group Holdings chief executive Chris Joblin and and ACC chief executive Scott Pickering made the announcement on Thursday.

Construction on the site, currently used as a carpark, will begin towards the end of this year.

The cost would be "in excess of $50 million," TGH chief executive Chris Joblin told media on Thursday morning.

"TGH is the largest land owner in the Hamilton CBD. [This] reconfirms our commitment to the CBD, we want to see it grow.

"It's our first big development inside the CBD. Our focus, aside from Ruakura, is around enhancing our property portfolio within Hamilton's CBD."

The building is designed as a low-rise, three-pavillion building, with food and beverage services operating out of the first floor.

The new environmentally-friendly complex would be the "physical manifestation" of the company's close partnership with ACC, Joblin said. It follows a memorandum of understanding between the two entities signed six years ago.

SUPPLIED The four-storey building will be located on the corner of Collingwood and Tristam streets.

A fully-owned subsidiary of TGH would own and develop the complex, which would be leased to ACC for an initial 15 years, with four rights of renewals of three years.

ACC chief Scott Pickering said Hamilton was a "critical hub" for the corporation, making up 18 per cent of the corporation's staff nationwide.

But those staff were currently operating out of three Hamilton sites.

While there was a lack of parking, the site was a short walk away from the transport centre.

Hamilton Mayor Paula Southgate said the move was a "big vote of confidence" for central Hamilton.

"Having an extra 650 workers in town is great news for city retailers and food outlets. They will bring extra vibrancy and to the city that's exactly what we want to see."

With a four and a half star "green" rating, the complex is designed to minimise the corporation's environmental footprint, boasting EV car, scooter and bike charging stations. It would also have solar water heating and an emphasis on reuse and recycling of materials.

In a statement, Parekawhia McLean chair of Te Whakakitenga o Waikato, the Waikato Tainui parliament, said the iwi was pleased to be partnering with the crown, but would continue to own the underlying whenua.

Nearby restaurants, walks and retails made the central spot a desirable place to work, Pickering said.

The partnership with TGH was more than that of a landlord and tenant, with more projects in the pipeline, he added.

"What we see is the opportunity to work together to look at programmes of injury prevention which will obviously help the iwi, the community. But we're also looking at options to work together on employment pathways.

"ACC as an entity is also a significant investor in its own right. Who is to say there aren't opportunities for us to work together in other developments?

"We're very open minded."