There is nearly $100 million worth of thin air sitting on top of the Los Angeles Convention Center – and downtown boosters want the financially strapped city to cash in on it.

Councilwoman Jan Perry, whose Ninth District includes much of downtown L.A., is putting together a proposal to encourage the city to sell the “air rights” above the Convention Center to nearby housing developers.

The concept involves taking square footage that could have – but was not – built on a piece of property and transferring it to other parcels with tighter zoning restrictions. In the case of the Convention Center – a low slung complex spread out on 20 acres – there are 4.3 million square feet of excess development under existing zoning.

The result: Taller condo buildings downtown. A building’s height now is capped by a formula based on the size of its lot. But developers can add stories to their buildings by buying the air rights from nearby parcels.

Already last month, the city transferred some of the rights from the center to a developer of a large mixed-use residential project several blocks away at a rate of nearly $23 a square foot. The transfer was done by the Community Redevelopment Agency of Los Angeles on an individual basis.

Using that price, the remaining 4.3 million square feet of development rights at the Convention Center would be worth $98.9 million. If demand for extra density increases, so too could the value of the air rights.

Perry confirmed her office is working on such a proposal, but she said the motion was too preliminary to discuss specifics of her plan.

“For the last 20 years we’ve been waiting for this day, and we are uniquely positioned right now because of the market,” said Perry of the demand for high-density projects. “It’s time to revisit this policy and look at what needs to be done.”

In addition to Perry’s proposal, there are similar motions from the city’s planning department that are before the Council’s Planning and Land Use Management committee. Those proposals would apply specifically to residential developers, who could access the excess density from any public and private properties that have not maximized their zoning.

Developers would have to pay a public benefit fee – an amount still being determined by the CRA – for transferring development rights from private properties. The money could be used for affordable housing, social services and other programs.

The goal is to help narrow L.A.’s widening housing shortage, said Jane Blumenfeld, a principal planner in the city’s planning department who authored the motions. Under the proposals, developers of commercial and industrialized projects would still have to go through the full approvals process for those projects.

While some city neighborhoods have thrown up barriers for higher-density development, downtown has the infrastructure to handle the added population and congestion, said Carol Schatz, executive director of the Downtown Center Business Improvement District.

“As a city we need to build up, we need greater density and downtown is the perfect place to do it,” said Schatz, whose group supports the proposals. “Not too many other neighborhoods in the city would say the same thing.”