Two of Australia's biggest developers are considering replacing plans for office buildings in Sydney's inner city with residential apartment complex projects as the RBA's cuts to interest rates lend further impetus to the local real estate market.

Mirvac hopes to replace the office tower it originally envisioned as part of its $400 million redevelopment of the Darling Harbour Harbourside Shopping Centre with a slimmer yet taller high-rise apartment complex situated on the opposite side of the site.

The developer has submitted a request to NSW Planning for a new Secretary’s Environment Assessment Requirements (SEARs) concerning a 166-metre residential building situated toward the northern end of the Harbourside Shopping Centre next to the new 35-storey Sofitel hotel which is currently under development.

The proposed apartment complex will replace the 45,000 square metre office tower that Mirvac previously planned to make a key part of its Darling Harbour overhaul, and encompass roughly 10,000 square metres less floor space.

On the other side of the water at Barangaroo South, Lendlease is mulling amendments to its original vision for the low-rise C1 building, and a possible switch from an office facility into a residential complex.

While Lendlease has confirmed that the adjacent C2 building will be a timber office complex, the developer has yet to finalise the fate of the C1 building, which is situated on Hickson Road just behind the trio of International Towers that comprise the core of the Barangaroo South development.

“C1 is approved in the concept plan for either commercial or residential use, though no decision has been made on its design or use,” said Andrew Wilson, managing director of Barangaroo South for Lendlease, to the Australian Financial Review.

The listed developer already has 900 apartments in the pipeline for its share of the Barangaroo site, while Barangaroo Central and James Packer’s Crown Sydney hotel-casino will also include a number of residential developments.

Lendlease and Mirvac expressed optimism about the housing market’s prospects during the release of their full-year financial results in August, while Sydney’s auction clearance rate has just tapped its highest level in 14 months.