17 Hartwell Breaks Ground: 312 All-Electric Homes for Lexington

Groundbreaking News: Lexington’s first major residential project approved under the MBTA Communities Act is underway—bringing 312 Passive House-targeted homes to Hartwell Avenue.

On July 16, crews officially broke ground at 17 Hartwell Avenue in Lexington. The former industrial lot is being transformed into a five-story, Passive House-targeted residential community. With 312 new apartments, a 361-space garage plus 47 surface spaces (408 total), and approximately 2,100 square feet of ground-level retail, the project is designed to bring energy-efficient housing and new amenities to the Hartwell corridor.

The Team Behind the Vision

Big names, bold goals. This project is powered by a joint venture between BXP and Northwestern Mutual. The project is being advanced by BXP in partnership with Northwestern Mutual, which secured a $98.7M construction loan. BXP retains a minority interest and serves as development manager. The joint venture acquired the 5.25-acre site for $21.84M in June 2025. CUBE 3 is leading the architectural vision, shaping a 347,000-SF wood-frame building, while Dellbrook | JKS is managing construction. Estimated construction value: $117M. H+O Structural Engineering coordinates closely with the design and construction team to keep structural decisions practical, cost-aware, and durable over the long term.

Responding to Lexington’s Housing Needs

More than just units—options that matter. Lexington has long been dominated by single-family homes, limiting housing diversity. Under the MBTA Communities Act, towns like Lexington are required to expand multifamily options near transit. 17 Hartwell is the town’s first major step in meeting this mandate—and with Passive House and LEED Silver goals, it’s raising the bar for quality as well as quantity.

Within the 312 homes, 47 inclusionary units are reserved for households earning up to 80% of AMI with long-term affordability. The unit mix includes 16 studios, 142 one-bedrooms, 24 one-bedrooms + den, 97 two-bedrooms, and 33 three-bedrooms—ensuring a range of housing choices.

"It was $500,000 saved on a $24M project. That is real money, right?"
- Dave Traggorth, Causeway Development

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Design A New Project

Designing for Sustainability and Community

Passive House meets lifestyle living. Energy performance is a defining feature here. The building will be all-electric, designed to meet Passive House standards, and targeted for LEED Silver certification. Beyond sustainability, the amenity package supports modern living: landscaped courtyards, a pool, children’s play areas, a dog park, and indoor/outdoor lounges.

Mobility and charging are built in: 20 Level-2 EV chargers (18 in the garage, 2 at the surface lot) and 504 bike parking spaces (468 long-term and 36 short-term). The site is 0.2 miles to the Minuteman Bikeway and 0.1 miles to MBTA Route 62.

From Planning to Progress

Approvals secured, shovels in the ground. The Town approved the Major Site Plan Review in December 2024 for the Village High-Rise Overlay (VHO) district and finalized a Definitive Subdivision in February 2025 to establish three new parcels and a cul-de-sac. The decision details a 4.5-story structured garage with 361 spaces plus 47 surface spaces for a total of 408. With approvals in place and demolition complete, Dellbrook | JKS is sequencing utilities and foundations for an efficient build. Target completion: August-2027.

What’s Next

Eyes on the structure. As construction goes vertical, we’ll share updates on the structural progress and envelope assembly.

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