It is the new home for advisory firm Ernst & Young, which has the signage, and Mirvac and boasts some of the latest in workplace practices.

Set across 37 storeys and offering 39,200 square metres of premium-grade office space, the building's distinctive design from architects Francis-Jones Morehen Thorp (FJMT), has been described as having "shimmering, golden curves".

But it is the internal function that the owners say has set the benchmark high for new office towers.

There are three categories: Town Hall, being communal space; Neighbourhoods, being workspaces, meetings rooms and offices configured around a main street; and the Main street, being a thoroughfare connecting all of the neighbourhoods.

But it's also the partnership with the International WELL Building Institute, where Mirvac's headquarters will actively promote the "health and wellbeing of its workforce".

The property is on the site of the former St George building at the northern end of the city overlooking Circular Quay. It will be the first of many new developments at that end of the central business district.

New South Wales Premier Mike Baird, officially opened the building, to be known as the "EY Centre", on Thursday. The opening was also attended by Mirvac's chief executive Susan Lloyd-Hurwitz; Carmel Hourigan, AMP Capital global head of property representing the joint owner of the site, AMP Capital Wholesale Office Fund; anchor tenant, EY; and the building's key partners and stakeholders.

Ms Lloyd-Hurwitz said Mirvac's vision was to create a "cutting edge workplace for leading organisations".

"Showcasing adaptable workspaces, green credentials, state-of-the-art technology and iconic design from architects, Francis-Jones Morehen Thorp, the building is testament to the hard work and collaboration between Mirvac and our many partners who have been involved in this pioneering project," Ms Lloyd-Hurwitz said.

Ms Hourigan said the completion of this landmark office precinct not only provides tenants with a new standard of workspace, "but adds another premium-grade office building to our investors' portfolio which will deliver superior investment performance for our clients both in the short and long term".

While the new assets are setting the bar high, older properties are now under pressure to change.

During the week the Minister for Resources, Energy and Northern Australia, Josh Frydenberg, moved to lower the mandatory disclosure threshold on commercial office buildings from 2000 square metres to 1000sqm.

According to CBRE's Pacific sustainability director Emma McMahon, the changes will create much-needed accountability for the owners of secondary office stock.

"The expanded Commercial Building Disclosure (CBD) program will create a level of much-needed accountability for the owners of B, C and D-grade buildings across the country," Ms McMahon said.

"Property Council of Australia research demonstrates that more than 60 per cent of the commercial buildings in Australia are B, C and D-grade buildings. Landlords of B, C and D-grade buildings will finally be prompted to explore energy efficiency opportunities and be accountable for their impact on the environment."

The chief executive of the Green Building Council of Australia, Romilly Madew, also welcomes the expansion of the CBD program, which follows a comprehensive review and public consultation period.

"The CBD program has been a critical driver in unlocking the emissions reduction potential of our buildings while raising awareness of building energy performance among occupants, delivering cost savings and creating jobs," Ms Madew said.