Construction work across Massachusetts, especially on the commercial side, has struggled to kick back into gear during the first half of 2021.

Nonresidential construction starts fell 14% in Massachusetts during the first six months in 2021 compared to 2020, according to ConstructConnect.

However, there are signs that things may be finally picking up, with construction starts overall, including residential, up 2% nationally through the first half of 2021, and with commercial construction starts posting an increase in June.

Locally, there are signs as well. Construction crews recently broke ground on four major projects, a $2 billion revamp of Somerville’s Union Square, a new lab complex in Cambridge, an apartment high-rise in Everett and a revamp of the World Trade Center complex in Boston’s Seaport.

For now, projects with major lab and/or residential components are leading the way back, with developers with plans for new office towers holding back as companies reassess their real estate needs in a post-Covid world, says Greg Vasil, CEO and president of the Greater Boston Real Estate Board.

By contrast, the lab market, supported by a booming life sciences sector, is red hot, while demand for new housing of all types is surging amid rising rents and condo and home prices, Vasil says.

The latest groundbreakings come as well in the wake of the launch of construction at Fenway Center, as plans finally take shape for a large, life sciences complex across Fenway Park on a deck over the Massachusetts Turnpike.

“You are seeing people start to pivot and change the uses,” Vasil says. “You are seeing an office projects converted to life sciences. There is still so much uncertainty as to what the office market will look like.”

Foundation Work in Union Square      

US2, a joint venture between Magellan Development; RAS Development LLC; Cypress Equity Investments and USAA Real Estate recently kicked off work on a $2-billion project that promises to transform Somerville’s Union Square.

Construction crews began work on the first phase of 2.4 million-sq-ft USQ project, slated to take shape on a 15-acre site across the street from what will be the Union Square station along the new, Green Line extension.

Contractors have begun putting in the foundations for the two major buildings that will make up the project’s first phase, the 194,000-sq-ft life-sciences building and a 25-story apartment tower that will have 450 units.

Gilbane Construction Co. is the main contractor on the seven-story lab project, which will be the first to complete. Cranshaw Construction out of Newton is handling the residential side of the first phase.

The lab building, 10 Prospect St., is slated to come online in the winter of 2022, followed by residential tower 20-50 Prospect St. in the spring of 2023, according to the developers. SGA Architects designed the lab complex. Höweler & Yoon is the design architect for the residential tower, with bKL Architecture is the architect of record.

“We are excited about the future transformation of Union Square into an urban employment center,” says Greg Karczewski, president of Union Square Station Associates (US2), the joint venture developing the project.

The lab complex and residential tower, however, represent just a quarter of the entire project.

USQ will eventually total 1.2 million sq ft of new lab and office space, more than 1,000 residential units, including 200 rented out at subsidized, below-market rates. There are also plans for 3.6 acres of “parks, open space and public realm improvements,” according to the developers, as well 140,000 sq ft of retail, 74,000 sq ft of arts and creative space, and 175 hotel rooms.

In Cambridge, DivcoWest recently announced it has broken ground on a 10-story-plus, 375,000-sq-ft life science building at at 441 Morgan Avenue.

The project is taking shape in a new, new 43-acre mixed-use neighborhood called Cambridge Crossing, which is under development where Cambridge,  Boston and Somerville meet.

The mid-rise lab building, slated for delivery in early 2023 for interior buildout by tenants, will feature 10 floors of labs, and two penthouse floors along with five outdoor terraces.

In Everett, Greystar recently announced the groundbreaking at 85 Boston St., a 650-unit multifamily project on a nearly six- acre site that was once home to the Wood Waste complex.

Plans call for a pair of six-story buildings.

Meanwhile, in Boston, the real estate arm of Fidelity Investments has begun a major overhaul of a well-known waterfront building, the World Trade Center complex in the city’s Seaport District.

Turner Construction Co. and Janey Construction Management are overseeing the big project, which involves, among other things, creating several new public spaces and adding 45,000 sq ft of retail.

The project will shut down the Commonwealth Hall exhibition space while renovating the event and ballroom space across the street at the Seaport Hotel, which Fidelity also owns.

“We are thrilled to start construction and begin to realize our vision for the new Commonwealth Pier, a project that furthers Pembroke and Fidelity’s vision for, and commitment to, Boston’s Seaport District,” said Pembroke President Edward Johnson IV, in a press statement.