The city called for the creation of 2,600 affordable housing units yesterday as part of its rezoning of the Hudson Yards. The Departments of City Planning and Housing Preservation and Development announced the strategy, which would generate 500 more affordable housing units than the city had first planned, as part of its final environmental review statement yesterday to the City Planning Commission, which will vote on the proposal November 22.

The Hudson Yards rezoning, which will bring 13,600 new residential units to the area, will use several strategies for generating the affordable units, including offering developers a density bonus in exchange for building subsidized apartments.

While the height limits in the Hudson Yards had been a floor-to-area ratio of 7.5, the city lowered the FAR to 6 when it announced its affordable-housing strategy this morning. For developers to return to a more attractive FAR of 7.5, they must agree to build some affordable-housing units in the vicinity of the market-rate site.

Developers were not happy yesterday with the news of the lower FAR.

“Developers who thought they could build to an FAR of 7.5 and bought land at Hudson Yards with that understanding, now are having to contend with an FAR of 6 or face building affordable units, which will cost at least $1 million to $1.5 million more,” the head of the lobbyist group the Real Estate Board of New York, Steven Spinola, said. “On the other side, this is a well thought-out plan, and I think they still want to build there. It is just that some of our members who had been looking at building in the area are now reevaluating or recalculating the dollars.”

Some critics of the city’s plan want the inclusionary zoning to be mandatory. “The fact that the plan does not require developers to include affordable housing in their plans is distressing,” the Manhattan borough president, C. Virginia Fields, said in a statement yesterday. “I am adamant that any affordable-housing provisions be mandatory. This would guarantee that no matter what the final count of affordable housing units is, the provisions would be protected.”

“Mandatory inclusionary programs, while successful in some other areas of the country, are not appropriate for New York,” Housing Commissioner Shaun Donovan testified yesterday in front of the City Planning Commission. “Because of the extremely high land and construction costs in New York City, a slight downturn in the rental or sale market can negatively impact the financial feasibility of a project. If this occurs, our newly rezoned neighborhoods will remain undeveloped and the benefits of the rezoning, including affordable housing, will go unrealized,” he said.

Council Member David Yassky and other city officials have been pushing for mandatory inclusionary zoning in the rezoning of Greenpoint-Williamsburg and other neighborhoods, although the city has not supported the plan.

Other programs the city will use to maintain and increase the amount of affordable housing in the Hudson Yards area include the 80/20 programs, under which developers receive tax breaks in exchange for subsidizing 20% of their units, and offering developers incentives to keep affordable housing from turning to market rate housing.

“Overall the city’s proposal for affordable housing in Hudson Yards is still a good plan, but this modification is going to make the cost of housing a bit higher, and I hope the market will bear it. The market is strong now, so it might, but a year from now, things could change,” Mr. Spinola said.