A prototype mass timber building has shown that even huge buildings can be constructed primarily with wood. The “Longhouse” is 12 metres tall and warmed via passive solar heating.
Because the construction of all kinds of buildings uses vast amounts of energy and natural resources, researchers have been seeking ways to make buildings more efficient and less dependent on emissions-intensive materials.
Now, a new prototype “mass timber” communal building designed by students at the Massachusetts Institute of Technology (MIT) is demonstrating that even huge buildings can be built primarily with wood.
Whereas the production of concrete, used in most of the world’s large buildings, involves large releases of greenhouse gases from the baking of limestone, construction using mass timber has the opposite effect, explained MIT research scientist John Klein. “The building is a carbon sink,” he said in a statement.
The energy-efficient “Longhouse”, which will be unveiled this October, uses massive beams made from layers of wood veneers laminated together into panels 15 metres long, 3 metres wide and more than 6 inches thick. These are then used to make a series of large arches, 12 metres tall and spanning 15 metres. With a pleated design, the roof accommodates solar panels and windows for passive solar heating.
“In North America, we have an abundance of forest resources, and a lot of it is overgrown. There’s an effort to find ways to use forest products sustainably, and the forests are actively undergoing thinning processes to prevent forest fires and beetle infestations,” explained Klein.
People tend to think of wood as a suitable material for structures just a few storeys high, according to Klein. But even taller buildings should ultimately be practical with this technology. One of the largest mass timber buildings in the U.S. is the 7,600-square-metre John W. Olver Design Building at the University of Massachusetts.
Tests have demonstrated that mass timber structures can resist fire as well or better than steel, because wood exposed to fire naturally produces a layer of char, which is highly insulating and can protect the bulk of the wood for more than two hours.
Photo credit: MIT Mass Timber Design