As the city’s makeover pushes more glass towers into the air, there have beens some big changes in the new buildings of these decades heading into the third decade of the 21st century.

Skyscrapers are now open to all, raised amid streetscapes to fit within and respect the buildings and around them.

And cutting edge technology is being deployed to minimise waste and power use, and maximise the use of resources close at hand, such as seawater, solar energy, rainwater and the rubbish generated by the occupants.

“In decades gone by there was a trend for office lobbies without activation or activity, but now ground levels have cafes and restaurants blended in to lobby spaces and buildings,” said Atlas Urban Design and Strategy director and Australian Institute of Architects Built Environment Committee chair Paul Walter.

“It’s not just the building itself, it’s also the way you arrive, for example the Wynyard Walk project (from Wynyard Station to Barangaroo South) has just been finished so you can go from the train station to the Harbour in seamless fashion whereas before it would have been getting into a car and arriving in a car park anonymously,” he said.

Barangaroo is where new residential and office towers meet the city, the Harbour and our history. Further walkways will include Barangaroo Wharf and two new pedestrian bridges over Hickson Rd.

It’s telling that more than half the site is public space. And while the developer of Barangaroo Central has yet to be announced, Lend Lease’s Barangaroo South is now reaching towards the sky.

By project’s completion in 2024, there will be 23,000 workers and about 3000 residents. Already there are 16,000 people working in the precinct’s three international towers. But impact is minimal. The entire precinct will be carbon neutral.

Rainwater is harvested, and the precinct recycles non-potable water and sends out the water that’s captured. More than 30 tonnes of food waste is turned into fertiliser every month. Perhaps the most innovative, however, is the use of seawater for district cooling.

So rather than use power-hungry traditional air-conditioning systems, sea water is pumped in from the harbour and run through the Barangaroo buildings to cool the air, with a series of filters used to free any sealife and the process monitored by UNSW to ensure the returned water doesn’t do any damage.

“We’re creating places that are going to be a part of everyone’s lives for a very long time, so we want to future proof them,” said Lend Lease’s managing director of Barangaroo South Rob Deck.

Elsewhere, huge towers are rising around the city from Quay Quarter, a 50-storey office block at 50 Bridge Street, to the Aspire and Holdmark towers in Church St, Parramatta.

But these trends can be seen on a smaller scale too. At 1 Denison St North Sydney, what will be the area’s tallest building and home to Channel 9 as it leaves Willoughby is slowly rising to the heavens. Designed by Bates Smart, it is being built with the neighbours in mind.

“I think in planning and architecture you are guilty until proven innocent and that’s a hangover from modernism,” said Bates Smart director Philip Vivian.

Nearby residents in neighbouring apartment blocks were suspicious - until they saw the design of the new building. It’s tapered to maintain privacy and light to the adjoining apartment block, and also features curved lines to allow broader views from the block.

“As we get into these denser clusters, I think buildings need to be doing a few things, ideally they need to respect the amenity of the neighbours, they need to revitalise infrastructure and they need to respect public spaces and not block out the sun,” Mr Vivian said.

Newly completed 177 Pacific Highway, just down the road has been constructed with many of these principles in mind. Vast amounts of space at the base are open to the public, and its design includes cutouts to let sun through to public spaces around it.

“They are being crafted and sculpted to respect the amenity of existing public spaces and revitalising those spaces, and creating new public spaces at the ground level - they make the city more livable,” Mr Vivian said.

Meanwhile at the $1billion redevelopment of Australian Technology Park in Eveleigh, Mirvac is building a new, three-building home for the Commonwealth Bank, which will eventually host 10,000 employees. Deep in an historic residential area, key to the design thinking is making it a space for the whole community.

“We want to change the way it feels, so walking through the site becomes part of your every-day commute, so it’s a place you want to go and when people look around they won’t feel like they are in a business park but a part of Eeveligh,” said Mirvac general manager of workplace experiences Paul Edwards.

There will be parks, community buildings, playgrounds and arts events in partnership with the nearby CarriageWorks. Harnessing solar energy, capturing rainwater and using water as heat mitigation for the buildings is all part of the planning for the new CBA home which are expected to be complete around 2019-2020.

The old and the new comes together dramatically at Central Park on the site of the old Carlton and United Brewery, with its hanging gardens and incorporation of the old brewery yard building. Rainwater capture, and solar energy are all harnessed, with the plant and equipment for it all housed in the old heritage brewery building at the heart of the precinct, part of the project designed by Tzannes Architects.

“(It) shows that it is possible to reuse our former old industrial buildings in practical, efficient, elegant and sustainable ways, and at the same time, to preserve their historic significance,” said Tzannes director Ben Green.

“This is important because people crave connection to their past as well as access to the latest technology,” he said.