The NSW Environment Minister says he will consider a recommendation from the state's Heritage Council to protect the iconic Sirius building on Sydney Harbour, despite his Government's plan to sell it off.

Aerial shot of the Sirius building, formerly social housing, at the Rocks in Sydney. ( ABC News: Andrew Griffits )

The Heritage Council unanimously decided the building contributed to the state's heritage, after receiving a nomination from the national trust.

"It's now up to the State Government to assess our situation in light of their own financial considerations," Heritage Council chair Stephen Davies said.

The Baird Government plans to sell the building, as part of the Government's sell-off of public housing throughout nearby Millers Point.

The Sirius complex sits in a prime location in The Rocks, with sweeping views of the harbour and the Opera House.

Built in 1979 for public housing tenants displaced during the 1970s when the area was being redeveloped, most residents were moved out throughout 2015, despite their protests.

Following its erection on the skyline adjacent to the Harbour Bridge, it was long-associated with, and seen as an outcome of, the Green Bans political movement of the 1970s.

Building could be 'harder to sell' with heritage listing

Mr Davies said the Heritage Council did not have enough information to put a dollar figure on what the building was worth, but said it would be harder to sell if it had a heritage listing.

Derided by some, but admired by fans of "brutalism", the UTS tower in Sydney. ( Photo: Andrew Worssam )

The building is considered one of Sydney's best examples of 1970s Brutalist architecture, alongside the University of Technology tower on Broadway and the Warringah Civic Centre.

Key to the Heritage Council's decision was the "aesthetic significance" of the building, Mr Davies said.

"We felt that it had enough significance for the state that it should be retained," he said.

"It had a rarity for social housing buildings for this particular period."

He said the building was in a fairly good condition, but the option for renovations remained on the table.

"There are other opportunities for adaptation, for alteration, so that could come into the next phase," Mr Davies said.

A spokesman for NSW Environment and Heritage Minister Mark Speakman said he would make a decision '"in due course".