"This means they are often marketed to higher income households," he said. "They aren't going to fix the affordability issue quickly although over time they could be a good source of stock." Developers also stand to rake in money if they succeed in increasing height limits, Professor Phibbs said. "Many developers have a preference for purchasing sites where they aren't currently allowed as a way of making some windfall profits." Sydney remains a "very horizontal" city with low densities despite recent building activity. Credit:Ryan Stuart Lane Cove Council on the north shore has been confronted with a number of proposals to significantly increase building heights. Developer Grocon wants height limits raised to 195 metres to build a 57-storey tower housing 366 apartments above the Telstra Exchange on the Pacific Highway at St Leonards.

The proposal, which will be considered by the Lane Cove local planning panel next month, said several residential towers up to 180 metres had been approved or proposed for the area. But a council spokeswoman said the site was not among four locations earmarked for "uplift". "St Leonards is not on the scale of Manhattan or Hong Kong," she said. Another developer is also seeking to amend local planning rules in Lane Cove West to increase height limits from 18 metres to 87 metres. Chris Johnson, the chief executive of Urban Taskforce, said while parts of Sydney will become more like Manhattan, most of the city will remain low-density suburbia. "Someone flying in to Sydney in 30 years will see a series of taller buildings, like Chatswood is currently, dotted across the city that emphasise where the railway stations are," he said.

An artist's impression of the 195-metre tower proposed for the Telstra Exchange site at St Leonards. Credit:Grocon Mr Johnson said councils benefited from increased heights by extracting money from developers through voluntary planning agreements. "In some cases this can amount to $100 million of benefits to the council in new parks, roads and community facilities that otherwise they would not be able to afford," he said. But Professor Phibbs said high-rises should not be relied on to house Sydney's growing population. "Some tall buildings probably aren't great places to bring up small children because they restrict the exploring opportunities for children and often have limited opportunities for exercise," he said.

Planning and Public Spaces Minister Rob Stokes said new developments should complement existing neighbourhoods. "Height is only one consideration in planning the future growth and character of an area, alongside form, scale, public space, and infrastructure capacity," he said. The tallest building in North Sydney is 149 metres, while the Metro Grand at Chatswood Interchange is 143 metres high. Two taller towers have been approved by North Sydney Council, which has set a maximum height of 227 metres for a site in the North Sydney CBD. Developers in Parramatta are also reaching for the sky, with a building called 8 Parramatta Square to soar 230 metres when it is completed in 2021.

Loading The tallest apartment building in Parramatta is 177 metres, but construction has begun on two residential buildings of 211 metres and 186 metres. A City of Parramatta spokesman said the maximum height control for Parramatta CBD is 200 metres for sites close to the train station. "Planning controls also allow for a 15 per cent bonus to be granted if a project demonstrates design excellence," he said. He said the council was considering increasing the number of sites where building heights would only be limited by aviation safety requirements. The City of Sydney, meanwhile, relaxed height restrictions to permit buildings up to 300 metres in parts of the Sydney CBD.

But the Star casino's proposed 237-metre luxury apartment and hotel tower in Pyrmont has provoked controversy over whether potential economic benefits should outweigh other planning considerations. Loading Tall towers can carry significant risks as the building defects controversy involving the Opal Tower and Mascot Towers shows. High-rise architecture also requires more steel and concrete than lower buildings as well as more energy to operate, said Philip Oldfield, the director of the architecture program at the University of NSW. "What this means is their carbon footprint tends to be higher," he said.