The Real Estate Board of New York is furious that the City Planning Department is forging ahead with plans to change zoning laws after at least one project has already been approved and underway while others are far into the pipeline.

The issue revolves around the use of “voids” for mechanical spaces that have no height limit or detailed rules.

These spaces have evolved as projects have become taller with some buildings, like 432 Park Ave., having several to allow wind to flow through while others are in place for elevators and chillers or to create better design.

There are around seven under construction or in planning with void sizes ranging from 80 to 190 feet high — and critics charge they are unsafe and merely used to raise the height of the apartments. Some of the cranky neighbors will also end up with shadows and blocked views.

One apparently caught the mayor’s wrath. This is an odd Rafael Viñoly design slated for 249 E. 62nd St. that resembles an observation tower and is proposed by an Orlando, Fla., firm.

Meanwhile, Gary Barnett of Extell Development has long been planning a 775-foot-tall residential condominium tower on West 66th Street that will also house a synagogue in its base.

Its Snøhetta design calls for a 161-foot “void” between the 18th and 19th floors that includes fire department pump rooms and fire department storage tanks.

Exterior details such as setbacks and an outdoor garden break up the visual impact of the tower.

The building’s foundation was started with approvals for a different design. On Nov. 2, 2018, the Building Department issued full permits while zoning “challenges,” including objections to the “void” that were made by Upper West Side groups, were all rejected.

Work was underway when those plans were revoked by Buildings on Jan. 14, 2019, and Barnett was given 15 days to “justify” the height of the void — although there is no current restriction or law that he do so.

But now, NYC is rushing through changes.

At the end of January, City Planning released a 48-page zoning text amendment to limit the height of voids and began what the Real Estate Board of New York’s president, John Banks, calls an “expedited” 30-day referral to the community boards “to satisfy political objectives and not to ensure the complex issues … are thoughtfully considered.”

In its letter to Planning Director Marisa Lago dated Feb. 6, and reviewed by me, REBNY’s Banks asks for a 90-day extension for the hearing now scheduled on March 13.

“There is no need to delay this hearing. This voids-proposal is simple and targeted to specific neighborhoods. There is ample time for the public to digest and comment on it in the coming weeks,” a City Planning spokesperson told The Post.

The Banks letter also warns that launching “an expedited public review process with no apparent purpose other than to stop construction of certain as-of-right residential projects … sends a chilling message to owners, lenders and investors about their ability to rely on the law.”

Indeed, Extell founder and President Barnett’s loan documents require him to “not acquiesce in or consent to any change in any … zoning law or other … restriction.”

“It could throw the loan out of balance,” explained a prominent mortgage broker who asked to remain anonymous.

Depending on the months of delays to the job, it could require Barnett to add equity or the lender to add funds and interest — or take other actions.

And such a law will give other lenders and developers pause once again and create further uncertainty about what the heck the city will come up with next that will affect investments to its vast real estate.