CDUS participates in Boston accelerator to explore possibilities of mass timber

Mass timber is making headlines, and for good reason. In recent years, Skanska teams across the U.S. have highlighted the material’s many benefits and capabilities, utilizing mass timber in over a dozen projects. This year, our USA Commercial Development (CDUS) team is joining the conversation in a unique way through their participation in the Boston Mass Timber Accelerator. As one of three awardees within the program, they’ve been resourced to thoughtfully envision how mass timber could intersect with a bold CDUS project on the horizon.

1 / 3 The Longwood Place Project reimagines the 5.8-acre site (currently known as the Simmons University Residential Campus), as a vibrant nucleus of sustainable and innovative workspaces, active community amenities, much need¬ed housing, and an inclusive public realm for the larger neighborhood.
2 / 3 For the purposes of the Accelerator, the USA Commercial Development (CDUS) team investigated a residential building and a commercial building, each in a simplified form that approximates the same floor plate size and shape of the buildings on the development site. For each of these use types, the Accelerator allowed the CDUS team to analyze a conventionally framed layout, a mass timber layout, and a hybrid layout that uses structural elements from each system.
3 / 3 Through the Accelerator the USA Commercial Development team evaluated the potential embodied carbon savings associated with each of the construction methods. The preliminary results indicated that mass timber can save over half the carbon of a similar conventionally framed building. Hybrid structures also benefit greatly from exchanging carbon-intensive slab on metal deck for CLT planks since the floor structure represents over half of the embodied carbon in the residential building and just under half in the commercial lab building.

The City of Boston is committed to reaching carbon neutrality by 2050. Similarly, Skanska aims to achieve net zero carbon emissions across operations and the value chain no later than 2045. Using mass timber in the built environment can help cities like Boston and companies like Skanska hit these milestones faster.

The Boston Mass Timber Accelerator program (Accelerator), now in its second year, is a formal mechanism empowering local developers and construction firms to strategically consider mass timber in their building plans. The program is the result of a partnership between Boston Planning and Development Agency (BPDA) and Boston Society for Architecture (BSA).

Selected participants for the Accelerator include groups with expertise in “sustainable development, design, and construction, and a proven commitment to achieving Boston’s carbon-neutral goals.”

According to BSA, mass timber “has the potential to reduce a building’s carbon footprint by as much as 39 to 52 percent over conventional structural materials, such as steel and concrete.”

Longwood Place serves as the perfect testing ground

In the Accelerator’s first cycle, smaller-scale projects made up the bulk of participation. For the program’s second year, BSA and BDPA wanted to aid larger-scale, high-rise projects in taking a closer look at the potential for mass timber.

CDUS’ Longwood Place project, a 1.7 million square-foot mixed-used development, fit the vision.

Longwood Place is a large-scale project in a prominent area of the Northeast. Situated in Boston’s Longwood Medical and Academic Area, it sits within an area that’s home to the nation’s top hospitals, medical research centers and academic institutions.

After Skanska delivers Simmons University’s Living and Learning Center in 2026, CDUS will pivot to Longwood Place. Project work will center on reimagining the 5.8-acre site currently known as the Simmons University Residential Campus.

Once finished, the area will include 1.7M square feet across five buildings inclusive of sustainable and innovative lab and research space, workspaces, community amenities, retail space and approximately 380 units of housing.

With both private and publicly accessible spaces, a variety of building types, and a multi-phase delivery spanning five to 10 years, Longwood Place was the perfect candidate for the Accelerator.

Imagining mass timber for the Boston skyline

The Accelerator gives awardees a $25,000 grant to explore the feasibility and embodied carbon potential of using mass timber construction. Participants aren’t required to commit to using mass timber, but rather explore its use in a variety of scenarios. WoodWorks provides technical assistance along the way.

After being selected by BSA and BDPA, our team got to work layering in the possibilities of mass timber with future early design plans for Longwood Place.

“The Accelerator gave us an opportunity to look into a sustainable building methodology that we have not used in this market before,” says Kyle Greaves, manager, real estate development. “We weren’t in the design phase, but we had a master plan. After being selected, we looked at this as an opportunity to collectively advance our understanding of mass timber.”

Being funded and supported to solely explore the use of mass timber allowed the team to realistically forecast the outcome of leveraging the material in different scenarios.

“We decided to simplify a footprint for a residential and a commercial building and conceive three options: a complete mass timber structure, a hybrid structure, and a conventional steel or concrete structure,” says Kyle.

Each scenario assessed how variables like material pricing, construction timeline and carbon emissions would converge.

“The exercise helped us see where each structure would shine or fail, and what the potential pros and cons were of each,” says Kyle. “We weren’t trying to choose a path forward necessarily, but we wanted the activity to inform our thinking as we enter into conceptual design this fall.”

Leaning into the mass timber moment

Our team finished the Accelerator with several takeaways in tow. A few of their conclusions highlight the complexities and opportunities associated with working with mass timber:

  • Benefits of incorporating mass timber in residential design and construction include reducing a building’s carbon footprint, decreasing a building’s weight to downsize foundations and shortening the construction schedule. However, mass timber material costs remain high which may limit its incorporation into buildings.
  • Vibration criteria and HVAC distribution are two elements in lab design that are more challenging to achieve in lab buildings with mass timber. With mass timber structures requiring taller floor-to-floor dimensions and mechanical, electrical, plumbing (MEP) and fire protection and structure running in stacked layers, fewer stories can be achieved, decreasing rentable area.
  • While mass timber’s prevalence in residential construction is showcasing what’s possible with the material, its feasibility is much less understood in the commercial lab building space. It will take more time and implementation of mass timber into commercial projects to ensure costs and schedules make sense for high-rise projects looking to deliver a mass timber structure.
  • Reduced schedule lengths due to the utilization of mass timber aren’t yet realized in the commercial lab space. Based on the scenarios explored, utilizing mass timber for such projects currently appears to result in the same or even longer project length.

While our team’s takeaways don’t shy away from the challenges of bringing mass timber to new heights, they also don’t cast off the possibilities of bringing mass timber to the commercial space.

“We went into this program knowing that it’s a learning process,” says Ally Riley, manager, real estate development. “We walked away knowing more about the high-level pros and cons, and the actual process for designing a mass timber building.”

In addition to leaning on the support of the program’s leads, Kyle, Ally and the project team looked to Skanska USA Building’s (USB) mass timber experience. Particularly on the West Coast, USB has self-performed timber erection. That experience gave USB a prime opportunity to share learnings and best practices around this construction methodology with our CDUS team.

Reflecting further, Kyle explains, “To make mass timber financially viable, you have to flip the traditional development process on its head. Mass timber leads with engineering and structure, and design follows. That’s not how we typically work in commercial development.”

“It’s been really interesting to learn how to put a team together and approach a mass timber building, in a way that’s different from how we’ve executed projects over the last decade,” he says.

Whether or not we see Longwood Place incorporating mass timber soon, the Accelerator has no doubt been a catalyst for shaping CDUS’ thinking around the sustainable material.

“It was instrumental in getting our market to start thinking seriously about mass timber,” says Kyle.