Heavy Timber Lightens the Environmental Load
Although the United States currently trails Europe and Australia in mass timber construction, projects such as Hines T3 in Minneapolis are turning the tide. The seven-story office development we completed in November 2016 has the distinction of being the first tall wood building in the country. Now at full occupancy, T3—short for timber, technology, and transit—serves as a kind of prototype for sustainable commercial office building development that also addresses the changing needs and values we see in the American workplace.
The environmental advantages of designing for mass timber are compelling. Not only is wood renewable when sourced from responsibly managed forests; it requires less energy to extract and process with a lighter carbon footprint than structural steel or concrete. Moreover, the carbon removed by and stored in wood is ongoing throughout the life of the building. Although timber is widely used in residential framing, adoption in commercial development could leverage the material’s sustainable benefits on a far larger—and more impactful—scale. When Hines approached us about designing a commercial property that felt more like a modern loft than a formal office, I knew that goal could only be achieved with timber technology.
Mass timber framing allows construction efficiencies otherwise impossible with traditional structural materials. Hines T3’s 180,000-square-foot structure was erected in a short nine-and-a-half weeks, and features glulam posts and beams with nail-laminated timber (NLT) floor and ceiling panels. An older, simpler, and more cost-efficient technology than cross-laminated timber (CLT)that has gained favor for similar efficiencies, NLT is formed by stacking wood structural members on edge and nailing them together sequentially. Panels can be pre-fabricated in sizes up to 12 feet by 100 feet, and are shipped ready-to-assemble.
T3’s strong environmental message isn’t only about construction. It appeals to the building’s tenants, many of whom work in the high-tech industry with leaders who have upended traditional notions of workplace culture and design. Today’s office workers demonstrate a value for ecological responsibility and, as consumers, support brands that practice what they preach. T3 tenants also appreciate the building’s authentic loft-style interiors, created by exposing the lumber structure and complementing it with steel, masonry, and concrete. The building’s streamlined form and weathered steel façade offer a further nod to the industrial roots of the North Loop warehouse district where T3 is located, another draw for today’s high-tech professionals.
Mass timber also holds promise for residential development in cities, such as San Francisco, in markets beyond corporate office. For an international wood building design competition, my colleague José Brunner and his team designed a mass timber high-rise that stacks affordable housing atop the Mission District’s El Capitan Theater and Hotel, using a kit of parts to maximize floor assembly efficiency and accommodate diverse floor plans. The 26-story building is designed to be erected in phases, dependent on need, “to give the potential developer the flexibility to add levels throughout time,” he says. Post-tensioned LVL beams in the shear walls ensure resilience in a seismic event, while a wood skin system reflects the Mexican baroque patterning of the existing building.
It is heartening to work with clients who value sustainable building practices—specifically mass timber. Plans are already underway to erect additional T3-style developments with similar programs; most immediately in West Midtown, a neighborhood in Atlanta that, of late, has attracted technology-driven companies. Located on the site of an old steel mill, the seven-story T3 West Midtown will house 200,000 square feet of office space with an abundance of “third spaces” that more closely resemble the hospitality sector than corporate office; places people associate with relaxation, refreshment, and social interaction.