The Materials Book

269 particle board or paper products. Despite the fact that the lamination process often reduces wood down to its chemical components (cellulose), it maintains its inherent strength. This strength allows CLT to be used in buildings already fifteen stories high, and has been engineered and tested up to forty stories. Combining CLT construction with high- density urban models, we have succeeded in answering a simple question: How would a city look if it achieved a 75 percent per capita reduction in energy consumption? How would it function? What kind of spaces would we create? What would be its public dimension? In this proposal, wood is “rendered” in three composite states within the technosphere: wild, cultivated, and processed. The wild state is represented in the riverine systems that abut the redevelopment sites. Instead of promoting a heavily altered riverfront landscape, the projects reimagine the adjacent riverfront park as a restoration or, better, a “rewilding” of the river wetlands, allowing it to resume its integral role in the native ecology. The second state in which wood is rendered in the projects is in a cultivated state. The cultivated state is represented in the extensive carbon plantation bands that run through the redevelopment site. Different from a tree farm or a forest or an urban park, carbon plantations are harvested and replanted on a cycle that is designed to maximize carbon sequestration and is 24.5 metric tons per capita annually. In other words, it would require a 70 percent reduction in US per capita greenhouse emissions to reach the emissions level of the average inhabitant of the five boroughs. This reduction is close to the 75 percent reduction in emissions required to limit surface temperatures to a 2°C increase, a limit that was once considered to be manageable. Unknown to most people outside the field, high urban (exoskeleton) densities present a ready-made solution to our environmental problems. Moreover, it is a solution that has been tested and proven many times over. Cycling Wood into the Technosphere While neither high-density dwelling nor wood construction alone can have a significant impact, together they would go a long way toward integrating urban production into the carbon cycle. The use of wood in high-density construction is made possible by new technologies that are grouped under the heading of cross-laminated timber (CLT). CLT transforms wood into a sophisticated industrial product capable of satisfying a great number of building requirements, including the construction of high-rises. Cut from the less valuable outer rings of a tree, the layers of CLT panels are composed of relatively small wood sections that would otherwise be milled into wood pellets for fuel or pulped for