Gov. David Ige on Thursday signed into law a bill authorizing the Department of Education to borrow up to $46.4 million through a “green energy” loan to reduce energy usage in its schools.

Part of a broader initiative to air condition Hawaii’s classrooms using a $100 million appropriation signed last year, the interest-free loan will speed projects that increase energy efficiency and lower electricity costs in public schools.

“We expect significant savings as this measure is implemented,” Ige said before signing House Bill 957 during a ceremony Thursday at the State Capitol.

The education department is authorized to install the new AC units without costly electrical upgrades. The $46 million loan will enable the state to find ways to cut down on energy usage, using those cost savings to pay off the loans.

Cooling Hawaii’s classrooms is a priority issue for the state. Unbearably high temperatures in the schools are linked to broader problems of poor academic performance and dwindling concentration.

The governor signed the $100 million bill last year to install air conditioning in class rooms.

In his 2016 State of State address, Ige pledged to cool 1,000 classrooms with new AC units by the end of 2016.

But the education department wasn’t able to meet that goal because of exorbitantly high bids from contractors to install AC units. Some contractor estimates came in at around $100,000 per classroom.

Ige said Thursday that he expects the education department to reach the 1,000-classroom goal by the end of August. The education department recently said it had successfully installed new air conditioning units in 456 classrooms statewide. The start of the new school year for students is Aug. 7.

“We’re going great guns at this point,” Ige said.

The $46 million loan comes out of a special fund distributed through the Hawaii Green Infrastructure Authority, which was established by the Legislature in 2013 to provide financing for clean energy technology.

Dann Carlson, an assistant superintendent, said the department will initially focus on replacing light fixtures with LED bulbs with the loan. The use of LED indoor lighting is estimated to save the state about $4 million in energy costs per year.

“If we find savings in the utilities bill, that’s what we would use to pay off the loan,” Carlson said.