Acknowledging the “considerable challenges” bedeviling his agency, John B. Rhea, the beleaguered chairman of the New York City Housing Authority, unveiled a plan Monday to squeeze hundreds of millions of dollars out of parking lots, walkways, open spaces and other areas.

Under the plan, which would take several years, the housing authority would lease land to private developers, who would then come up with projects featuring a mixture of apartments and commercial and retail space. At least 1,000 of those apartments — or perhaps 20 percent of all the units, according to housing advocates — would be set aside for low- and moderate-income families.

No buildings would be demolished, or residents displaced, and the revenue from the leases — estimated by the agency to eventually reach hundreds of millions of dollars — would be split between operations and capital programs.

And no, Mr. Rhea said repeatedly, “this is not a plan to privatize Nycha.”

“It wouldn’t require a single penny of housing subsidies,” Mr. Rhea said, during a breakfast speech to the Association for a Better New York, an influential civic group. “Nada.”