This time of year, the New Hampshire State House and the Legislative Office Building are bustling with public hearings, committee meetings and voting sessions. Come summer, half of the legislative hub will close for 18 months or more for renovations, displacing senators, bill hearings and other public business until 2027.

“We’ve done some temporary fixes to make the air handling work, but modern standards and a modern system would be better for that building,” said Charlie Arlinghaus, the commissioner of the state Department of Administrative Services. “It’s one of the most used buildings in Concord by the public, and you want to hold it to a high standard.”

The State House, including the House of Representatives and Senate chambers, will remain open.

Arlinghaus said the roughly $7.5 million project will upgrade the heating, venting and cooling system. The Legislative Office Building, or the LOB as it’s known in Concord, is more than 100 years old and still has its original HVAC system.

The antiquated system struggles to keep the building warm in the winter and cool in the summer, especially in the basement, where several senators have offices.

Structural repairs will be made to the small parking garage that’s attached to that building. Hopefully, Arlinghaus said, the renovations will last another 50 to 75 years. One block over, work has already begun on a new 400-space garage for lawmakers and staff.

The renovations and ensuing upheaval pose logistical challenges for public access to the legislative process and hearings. The logistics of moving everything out of the Legislative Office Building is no small task. Terry Pfaff, the chief operating officer of the State House, has already started preparing.

Likely starting in late June, which is a slower period for state government, meetings and hearings will be moved to One Granite Place, the headquarters for the state’s judicial branch, where Pfaff is renovating the top two floors into about 20 committee rooms.

“They shouldn’t miss a beat,” Pfaff said. “They’ll be able to hold the committee meetings just like usual, and they’re all modern, got good air exchange in there, good lighting. So it’ll be a nice, bright place to do the people’s business.”

Pfaff said he’s kept public access at the forefront in his $1.5 million redesign of One Granite Place. The complex has ample parking and public access points, along with the same safety and security protocols as the State House.

But the transition won’t be without its bumps. While the State House and LOB are right next to each other, allowing lawmakers, staff, lobbyists and the public to walk between the two buildings, One Granite Place is more than a mile away.

“It’s going to be a great place to conduct business, but it won’t be as handy because we’re going to have a little logistical issue with folks going back and forth,” Pfaff said. “It’s going to be kind of a split legislative process this coming next session because of the logistics involved.”

House of Representatives hearings will make the move to the new location while Senate hearings will stay in the State House. Trying to toggle back and forth will take some planning. Located off the north end of Rumford Street, One Granite Place is a five-minute drive and 33-minute walk from Capital Plaza downtown.

More inner workings of the Legislature will be split, too. Democratic senators, whose offices are housed in the Legislative Office Building, will move to the State House annex. That’s at 25 Capitol St., where the state’s Department of Agriculture used to be located and renovations are just finishing up. Pfaff said it’s almost ready for senators to move in.

Sharon Carson, the Senate president, said in a statement that the logistics of it all will “present a challenge” but that the House and Senate will coordinate to make sure legislative work forges ahead.

That hasn’t soothed the concerns of lawmakers. State Sen. Donovan Fenton, a Keene Democrat, worries the move will disrupt constituent services and public participation.

“Not only will my staff have to figure out where we’re going, but our constituents who want to testify on bills are going to have to figure out where these bill hearings will be, where these committee meetings are going to be,” Fenton said. “I hope it’s an easy transition and a transparent transition just so that … our constituency knows where we are and what we’re doing.”

More construction

The Legislative Office Building isn’t the only part of the state’s stronghold in downtown Concord getting a makeover. The state is constructing a new parking garage for legislators catty-corner to the State House.

For months now, an expansive pit has occupied the block at the intersection of State Street and Capitol Street – which was a former bank building later occupied by the Department of Justice – and it will remain there for months to come, until the garage begins going up in late summer.

Sketches of the project include a three-tier garage to hold 409 spaces, adorned with a central stairwell and granite exterior to help it blend in with the rest of the state buildings in the area.

Arlinghaus said they’re still in the longest phase of the project, treating soil and removing asbestos.

“Once it starts to go up, it will go up fairly quickly,” Arlinghaus said.

Charlotte Matherly is the   statehouse reporter for the Concord Monitor and Monadnock Ledger-Transcript in partnership with Report for America.