It can be a tough call with developers and architects both often having to grapple with smaller sites or reconfiguring land once used by old commercial or industrial buildings while trying to create innovative buildings that can avoid the threat of over-density.

"With the NSW regulations and many councils also having strict controls in place on sunlight, cross-ventilation, overshadowing and amenity, as well as having to preserve the character of an area, it's going to get harder and harder," says principal of Allen Jack + Cottier Architects, Peter Ireland.

"But as it gets harder, the challenges often produce better solutions. Sometimes it can be so frustrating, it's like banging your head against a wall. But then sometimes it results in a vision so good it makes you dizzy."

Ireland had been wrestling with an exceedingly tricky site, with potential for overshadowing, in the middle of built-up North Sydney. The resulting design for apartment building Polaris has won plaudits from everyone involved in the planning process (see cover property).

Chris Johnson, chief executive of the Urban Taskforce and a former NSW government architect, believes great buildings in high density areas need to address all the challenges, as well as looking good and feeling comfortable to live in.

"They need to address the street level and have impressive entrances," he says. "They also need amenities, whether communal open spaces, gardens, gyms or pools, and have plenty of character.

"I think a bit more inventiveness is needed with designing apartment buildings in Sydney. There's more in Melbourne, so we need to pick up a little bit. But there have been a number of excellent projects that meet the challenge of density (see box)."

One of those is the Casba development in Danks Street, Waterloo. The density of the area, says Michael Grant, chief executive of developer Cornerstone Property Group, was offset by careful planning and design.

"We'll always be the high street of South Sydney," he says. "But there's a beautiful sense of privacy and simplicity with deep balconies, a number of open courtyards, private boutique spaces and features like a reflection pool throughout the complex.

"The retail mix was also carefully integrated into the residential element to add to the Morocco-meets-southern-Spain feel."

The 28-storey Ovo tower to be built in Green Square, has also been singled out for praise. Paolo Razza, development director of developer Mirvac, says because high density often occurs in areas close to public transport, retailers and service providers this gives residents great facilities close at hand.

"And we wanted to create a marker for the area with Ovo the tallest tower there, with its curves defining the entrance to the town centre and being instantly recognisable from the distance. It's challenging building in high density areas but we believe we're been able to optimise the sunlight and outdoor space while minimising wind and noise," Razza says.

It's a vision of the future

Chip Kariyawasam (centre) with his father Sarath, sister Erosha (left) and mother Pushpa.

The prospect of living in what's set to be the highest density precinct in Australia didn't deter software consultant Chip Kariyawasam when he was looking for a place of his own to buy.

He visited Green Square, to the south of Sydney's CBD – the area that's set to have an average density of around 20,000 residents to the square kilometre once completed – and still liked the vision for its future.

"I've been deliberating for the last six to eight months about what to buy," says Kariyawasam, 26. "But when I went to Green Square and looked at the renderings for the apartment building Ovo there, I thought it looked pretty good.

"The density doesn't really bother me. I look at investments over a five to 10-year term and by then Green Square will have taken off. I think Mirvac is a tried and tested developer and I felt it was a good idea to buy in what's going to be one of the biggest buildings in the development, which is going to be a landmark, and that's why I opted for a higher floor, too."

Higher-density living ultimately means a lot more amenity too, Kariyawasam feels, with plenty of shops, cafes and restaurants being attracted to the area. Being right by the train station is another plus.

As a result, he finally decided to make the plunge, and bought a two-bedroom apartment on the 24th floor of Ovo for $950,000.

Yet he's still not sure whether it'll be his home when it's built, or purely an investment. "A lot can happen in the time before it's finished," he says.

Polaris, 18 Berry Street, North Sydney

Price guide: $550,000-$2 million+

When developer Fuji bought a site in North Sydney for an apartment building, just 600 metres to the train station and bus interchange and 350 metres to Greenwood Plaza, there was already a development application in place. It wasn't, however, overly popular.

Many were worried the apartments wouldn't get enough light in a neighbourhood that was already quite densely developed, and there could be overshadowing issues with neighbouring buildings. As a result, award-winning architects Allen Jack + Cottier were brought on board to come up with a better solution.

"So we plotted the sun's rays to the site backwards to create an envelope on the site that would allow as much sunlight as possible, and create no overshadowing," says principal Peter Ireland. "That led to the crystalline form we've ended up with for the building, Polaris."

The building's bulk and height has been reduced, but an innovative design – and unusual trapezoid shape – allowed more apartments to be included: 218 one-, two- and three-bedroom apartments over 24 storeys. Many have spectacular views and all have access to a landscaped communal "sky" garden on the top of the building, and a protected outdoor barbecue  entertainment area.

Polaris has studios (45-46 square metres) from $550,000; one-beds (from 50-71 square metres) from $610,000; two-beds (75-80 square metres with wintergardens 10-90 square metres) from $1.2 million; and threes (98-170 square metres with balconies 12-23 square metres) from prices yet to be set. Completion due 2018. polarisnorthsydney.com.au. Phone 8268 2388.