New approach to sustainable building takes shape in Boston
A five-story mixed-use structure in Roxbury, designed by architects from MIT, represents a new kind of net-zero-energy building, made from wood.
A new building about to take shape in Boston’s Roxbury area could, its designers hope, herald a new way of building residential structures in cities. Designed by architects from MIT and the design and construction firm Placetailor, the five-story building’s structure will be made from cross-laminated timber (CLT), which eliminates most of the greenhouse-gas emissions associated with standard building materials. It will be assembled on site mostly from factory-built subunits, and it will be so energy-efficient that its net carbon emissions will be essentially zero.
Most attempts to quantify a building’s greenhouse gas contributions focus on the building’s operations, especially its heating and cooling systems. But the materials used in a building’s construction, especially steel and concrete, are also major sources of carbon emissions and need to be included in any realistic comparison of different types of construction.
Wood construction has tended to be limited to single-family houses or smaller apartment buildings with just a few units, narrowing the impact that it can have in urban areas. But recent developments — involving the production of large-scale wood components, known as mass timber; the use of techniques such as cross-laminated timber; and changes in U.S. building codes — now make it possible to extend wood’s reach into much larger buildings, potentially up to 18 stories high.
Several recent buildings in Europe have been pushing these limits, and now a few larger wooden buildings are beginning to take shape in the U.S. as well. The new project in Boston will be one of the largest such residential buildings in the U.S. to date, as well as one of the most innovative, thanks to its construction methods.
Described as a Passive House Demonstration Project, the Boston building will consist of 14 residential units of various sizes, along with a ground-floor co-working space for the community. The building was designed by Generate Architecture and Technologies, a startup company out of MIT and Harvard University, headed by John Klein, in partnership with Placetailor, a design, development, and construction company that has specialized in building net-zero-energy and carbon-neutral buildings for more than a decade in the Boston area.
Klein, who has been a principal investigator in MIT’s department of architecture and now serves as CEO of Generate, said large buildings made from mass timber and assembled using the kit-of-parts approach he and his colleagues have been developing have a number of potential advantages over conventionally built structures of similar dimensions. For starters, even when factoring in the energy used in felling, transporting, assembling, and finishing the structural lumber pieces, the total carbon emissions produced would be less than half that of a comparable building made with conventional steel or concrete.
Klein, along with collaborators from engineering firm BuroHappold Engineering and ecological market development firm Olifant, will be presenting a detailed analysis of these lifecycle emissions comparisons later this year at the annual Passive and Low Energy Architecture (PLEA) conference in A Coruña, Spain, whose theme this year is “planning post-carbon cities.”
Interior view shows the new building’s first-floor community co-working space. Courtesy: Generate Architecture and Technologies/MIT[/caption]
With U.S. building codes now allowing for mass timber buildings of up to 18 stories, Klein hopes that this building will mark the beginning of a new boom in wood-based or hybrid construction, which he said could help to provide a market for large-scale sustainable forestry, as well as for sustainable, net-zero energy housing.
“We see it as very competitive with concrete and steel for buildings of between eight and 12 stories,” he said. Such buildings, he added, are likely to have great appeal, especially to younger generations, because, “Sustainability is very important to them. This provides solutions for developers, that have a real market differentiation.”
He adds that Boston has set a goal of building thousands of new units of housing, and also a goal of making the city carbon-neutral. “Here’s a solution that does both,” he said.
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