Those plants that can clean up cheaply, and thus emit less than allowed, are then free to sell their unused rights to those for whom pollution control would be costly.
There is the often arduous and lengthy process of buying up air rights — or unused development rights — from adjacent properties; borrowing hundreds of millions of dollars in financing; and engineering architecturally unique structures that can rise 90 stories or more.
He prefers to sell SL Green the unused development rights, or air rights, from Grand Central, rather than let the city permit SL Green to build a taller tower in exchange for the Grand Central improvements.
Or, a developer could buy unused development rights, or air rights, from the owners of Grand Central; St. Patrick's Cathedral, on Fifth Avenue; or St. Bartholomew's Church, on Park Avenue.
Mr. Macklowe bought unused development rights, known as air rights, to eight townhouses on 57th Street to be able to add height to the building.
To compensate for the loss of the elevated plaza and other changes, Goldman Sachs proposes to acquire 364,000 square feet of unused development rights, known as air rights, from the low-rise South Street Seaport district.
The developers William L. and Arthur W. Zeckendorf are paying a record $600 per square foot this week for unused development rights, sometimes called air rights, so that they can add floors to a planned ultraluxury tower on 60th Street in the old Silk Stocking District, according to real estate executives.
Air-rights rules allow the property owner to transfer the unused development rights — the difference between the existing building and what is allowed under the zoning code — to an adjoining property owner.
A developer could then buy additional development rights from the city or from landmarks like Grand Central Terminal itself that have unused development rights.
Its developer, Gary Barnett of Extell, who is generally considered the grandmaster of the chess game that empowers air-rights assemblages, spent more than 15 years, and umpteen millions, buying up unused air rights from a string of smaller properties surrounding his tower.
