City Hall is cracking down on greenhouse gas emissions.
New mandates from Mayor Bill de Blasio would require building owners to slash energy use by the year 2030.
That could mean upgrading boilers, water heaters, windows and roofs to make buildings more energy efficient.
Owners of large buildings could be fined as much as $2 million for not complying.
"We're clear about the fact that we're not waiting on President Trump and cabinet of deniers to address this crisis, we have no such illusion," de Blasio said. "We understand it's our responsibility, we're not going to put our heads in the sand, we're not going to run away from the Paris Accord. In fact, we're going to embrace it even more intensely than ever."
The regulations first need to be approved by the City Council.