The National Trust of Australia urged the museum’s world-leading Steam Revolution display remain.

The building’s concrete floor had been specifically engineered to display steam engines and locomotives and any removal of infrastructure would be extremely costly, and prevent a far more worthwhile expenditure of a limited budget on other key new components of the proposed design. Any planning approval should await a final decision on a bid to expand the buildings’ heritage listing, it said.

The City of Sydney supported in principle the revitalisation of the Powerhouse Ultimo site as a museum space for the community but sought further clarification of changes to the retained buildings.

Town Hall added: “It should be ensured that there is no reduction in exhibition space.”

Heritage specialists, Design 5 Architects, said the proposal almost completely erased the “intangible and innate connection between the buildings and spaces, and the collection, and what is not erased is entombed in a new structure to conceal it.”

The process that has resulted in this proposal has been fatally flawed from the beginning, being driven by an agenda to dismantle and destroy the museum, an investigation and decision-making process that had little to no transparency and the unwillingness of a new government to call out and rectify these errors,” the submission said.

“We know this lack of transparency is true as we were one of those consultants engaged by government to investigate the significance of the Powerhouse Museum and complete a draft Conservation Management Plan … to guide its future, including major changes.”

‘[Powerhouse] collection holds artefacts of world significance. The current dumbing down of a once proud institution will be catastrophic.’

Historian Dr Shirley Fitzgerald

Docomomo, a non-profit organisation lobbying to save modern buildings, predicted very little, other than the structural ribs of the vaults of the 1988 Wran Wing and Galleria would be retained. Even then, the south end of the Wran Wing was “indicated for demolition and truncation in length”.

Historian Dr Shirley Fitzgerald said the Powerhouse Museum was “not just any old museum”.

“Its collection holds artefacts of world significance,” she wrote. “The current dumbing down of a once proud institution will be a catastrophic loss of excellence to Sydney, NSW, and the wider community.”

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Author Judith White, an advocate of sustainable public funding for cultural institutions, said revitalisation was a poor name for the plan.

“In fact, it’s a death warrant for an excellent museum, and a broken promise to the people of NSW,” she said.

Former government architect, Lionel Glendenning, who designed the 1988 building adaption, said he would have been expected to be consulted in any heritage revitalisation plan but had not.

In every area, the planning documents were “inadequate, tendentious, inconsequential, erroneous [and] amateurish based on incorrect references or irrelevancies”.

The project now goes to the Department of Planning to assess whether it is worthy of state significant development status. Expressions of interest have been called for construction partners.

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