Suburbs across Sydney could be revitalised and supply issues eased by knocking down and redeveloping existing apartment blocks.

The Renewing the Compact City report, developed by the University of New South Wales’ (UNSW) Department of the Built Environment, identified more than 8000 blocks that would be viable redevelopment opportunities.

Of the identified buildings, 2600 would be suitable to be redeveloped as walk-ups (blocks with only stairs), while another 5700 would be suitable to be redeveloped as high rise buildings.

According to the report, renewing existing residential buildings is being recognised as a necessary measure as population density grows in cities such as Sydney.

“Over a long period, efforts to implement urban consolidation and densification policies have focused on renewal of former industrial land often located in central locations. As the availability of these sites slowly diminish, there is an emerging recognition that implementing these policies in areas identified for renewal will require a reworking of existing residential areas in Sydney,” the report said.

The identified blocks are located predominantly in suburbs around Sydney’s eastern suburbs, lower north shore and the Cronulla area.

UNSW City Futures Research Centre professor Bill Randolph said the blocks in those locations had been deemed viable due a combination of reasons.

“We put together a lot of complicated factors that would govern the viability of these projects, such as cost of buy-out, building costs, management on-costs, and a developer's profit margin of 20 per cent,” Professor Randolph told The Sydney Morning Herald.

"Then we looked at local factors such as the size of the blocks, the current floor space ratio and height restrictions."

However Professor Randolph told the SMH the redevelopments may not solve housing affordability issues, as developers would be unlikely to revitalise apartment blocks outside of the city’s prestigious suburbs.

“When we look at housing affordability, in some areas like Cabramatta, for instance, the numbers don't stack up,” Professor Randolph said.

“Developers are not going to buy up and knock down older buildings if they can't make a profit on the new ones. And in some areas the property prices simply won't sustain renewal.”