There was a risk the new home of the Powerhouse Museum would not be a world class, architecturally beautiful building, according to a report prepared for Parramatta Council.

Deloitte Economics was commissioned by council to assess the economic impact of a new cultural precinct with the Powerhouse Museum as the NSW government negotiated to acquire the riverbank site known locally as the David Jones car park.

The Powerhouse Museum in Ultimo. Credit:Louise Kennerley

The same analysis found the economic impact of a $500 million museum build could be as little as $106 million if international and domestic visitors did not come in the big numbers predicted, an upper house inquiry into the Powerhouse move heard..

"If that's what you are looking in terms of economic impact," Greens MP David Shoebridge said at Tuesday's hearings, "it's a pretty poor investment for the region."