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An unusual new glass cafe near Auckland's waterfront opened on Tuesday after property investors Equinox Group developed the building.

The completely transparent cafe in Queen Elizabeth II Square, near Quay St, covers just 18sq m.

But big doors open out to form walls and fixed glazed canopies, which expand the seating area to 60sq m.

Equinox and two investors own No 1 Queen St, the 21-level HSBC House. The new cafe was built outside the main entrance to this office block, partly to cater to its tenants.

Lohsing Cheng, property and development manager at Equinox, said people were initially surprised that a building could be developed in the public square opposite Britomart.

"A lot of people didn't realise that was private land," Cheng said. "It took us three years to get through the resource consent process."

The cafe, which Cheng said could seat 30 people, cost about $500,000 - a significant portion of that spent on paving surrounding areas.

Cheng said it was during the proposed upgrade of Britomart that Auckland City came to Equinox inquiring about replacing the red paving of the old square with the clay pavers now laid down Quay St's footpath.

"With the forecourt held in private ownership, we felt it important to upgrade from the red pavers to something in keeping with the design of the building," Cheng said.

The cafe was designed by Geoff Land and Patricia Han of Stephenson & Turner. They were asked to develop a structure small enough to stay out of pedestrians' way, but large enough to operate as a cafe with sheltered seating. "Couple that with a requirement to be a reasonably all-weather structure and the end result is what you see," Cheng said.

"It's been a four-year process from the concept stage to being able to develop the structure. The time it has taken to get to this point highlights the significant level of interest the public has had in this part of town and Auckland City's determination that we get this development right."

Han said she was inspired by the amount of glass in the square: the covered walkway between Quay St and Customs St and the many glass bus shelters.

The structure was container-like and the fixed canopies acted as rain screens, which allowed an area more than three times the footprint of the building to be used, she said.

"Our brief was to create an attractive new cafe in the forecourt of No 1 Queen St that would encourage use of the space as a point of interaction as well as part of an important thoroughfare between the Ferry Building and QEII Square," Han said.

The structure aimed to be a focal point within the forecourt but also cater to office tenants and the public.

"This cafe was conceived as a piece of urban furniture. Its compact form adapts to its environment as required through the folding and unfolding of its shell. The folding glass doors along the north and south sides play an important part in the flexibility of the cafe's operation while ensuring transparency and protection from the wind."

From an urban design point of the view, the development sought to keep the visual link between the Ferry Building and the lower part of Queen St , Han said.

Three lamp shades by designer David Trubridge are a focus. Equinox principals are Kerry Knight, of Knight Coldicutt, and Chong Du Cheng.