A new state law forcing the city to offer space or funding for new or growing charter schools was hailed as a big win by the charter sector last spring. Now, some charter advocates are planning a rally in lower Manhattan to ask for more.

Next Tuesday, charter-school advocates will host a demonstration calling for the state to provide facilities funding for existing schools, which didn’t benefit from the new law. The event, being organized the Northeast Charter Schools Network, the New York City Charter School Center and the Coalition of Community Charter Schools, will set the stage for one piece of the sector’s upcoming fight for more favorable legislation.

“We have a situation right now where approximately half of the charter schools in the state have no access to facilities funding,” said Northeast Charter Schools Network CEO Kyle Rosenkrans, whose group also filed a lawsuit upstate over the issue.

The event is expected to draw many schools from the Coalition of Community Charter Schools, a newly-established group made up of smaller, independent schools as well as many unionized schools.

A top  priority for the sector when the legislative session begins in January is to raise or eliminate the state’s charter-school cap, which leaves room for only 28 more charter schools to open in the city. That issue is especially important to charter school networks like Success Academy, which is opening 14 new schools over the next two years and plans to continue expanding.

But a bigger issue to independent charter schools, many of which operate in private space and don’t have plans to expand into a network, is reducing the burden of rent, energy bills, and other facility-related expenses. Representatives and parents from more than a dozen schools plan to attend Tuesday’s event.

“We pay a mortgage, security, cleaning services, repairs,” said Vasthi Acosta, principal of Amber Charter School in East Harlem, who said she spends $80,000 annually on her energy bill. “Some relief would help so much.”

New York City is one of the only districts in the country to offer many charter schools rent-free space inside of district buildings, and new and expanding charters will have their facilities expenses covered by the city under the new state law.

Sixty-seven city charter schools operate in private space and receive about $2,300 less per student than those in city-owned buildings, according to a 2011 independent analysis. Statewide, there 127 charter schools in private space that spent a total of $118 million on facilities last year, according to the charter center.

“The state was able to do something for the new charters, but they forgot about the old charter schools,” Acosta said.

Rosenkrans said one proposal would allow the schools to tap into the state’s $2.7 billion building aid program. That idea was part of last year’s negotiations, but did not make it into the final deal.

But opponents say any available state education funding should go toward traditional public schools still hurting from the steep budget cuts of three years ago, not toward offering additional benefits for charter schools.

“We not adequately funding our public schools,” said Billy Easton, executive director of the Alliance for Quality Education. “Students are losing art, music, sports, guidance counselors as a result of the underfunding.”

This year’s state budget increased school funding by 5 percent, or $1.1 billion. A coalition of education groups said Thursday that next year’s increase should be $1.9 billion, though Easton said even more was needed.

Tuesday’s rally will be smaller than the October rally hosted by Families for Excellent Schools, which consisted mostly of large charter-school networks. Those schools are not expected to attend on Tuesday, organizers said.

“Most of the schools are not in private space,” Rosenkrans said. “That’s the real practical reason.”