Cross-Laminated Timber: The Sustainable Choice of Microsoft Silicon Valley

In the face of global climate change, construction and real estate professionals are increasingly seeking ways to build and operate buildings more sustainably.

The most obvious of these is reducing operational carbon: that is, the carbon emitted to run the building. That’s important—and it’s something the industry has made dramatic improvements in by both increasing energy efficiency with things like LED lights and smarter building management systems, and using renewable energy with things like on-site solar panels and offsite renewable power purchase agreements. But there’s another aspect of sustainable building that is lesser known but equally significant: reducing embodied carbon.

What is embodied carbon? It is the greenhouse gases emitted to build a structure in the first place. Think the energy used to extract and process the raw materials that make the concrete, then the energy used to transport it to construction sites.

Over the last decade Microsoft has demonstrated a rigorous commitment to carbon reductions, resulting in the company achieving carbon neutrality across its global operations since 2012. In Mountain View, California, this commitment to environmental sustainability has driven the redesign of our Silicon Valley campus, now underway. Key initiatives to that end include restoration of the surrounding habitat, thermal energy storage, data-driven optimization of power use, and net-zero water usage—in which 100% of the building’s non-drinking water will come from rainfall or on-site recycled water. 

Less familiar, but no less significant for sustainability, is the project’s use of a breakthrough new material as its main structural component: cross-laminated timber.

Cross-laminated timber (CLT) is the term for prefabricated, solid engineered wood panels, crafted by stacking several layers of kiln-dried lumber boards in alternate directions and bonding them with structural adhesive. As durable as concrete and requiring significantly less energy to produce a comparably strong steel beam, CLT is proving an increasingly popular alternative to both. Lightweight but strong, it performs better against fire and earthquakes than conventional structural materials. Because prefabricated materials arrive at a job site cut and ready to go, they go up faster and leave less waste than concrete or steel. CLT is also beautiful, creating ceilings and columns which don’t need drywall thus reducing material usage while bringing the warmth of natural wood indoors.    

Foremost among its benefits for Microsoft, however, is what CLT doesn’t bring: significant amounts of embodied carbon. That’s because CLT is not as energy-intensive to produce, and because as a building product it stores carbon dioxide just the way a tree would.

How much CLT will be used for Microsoft Silicon Valley? Some 345,000 square feet of it, or 2,400 tons. That amount represents over half the structural component of the campus—and puts Microsoft Silicon Valley on track to become the largest wood structure in the US, by volume of wood used. To ensure that it’s sourced from from responsibly managed forests, 100 percent of the wood we buy will be certified by the Forest Stewardship Council.

And Microsoft is dedicated to reducing embodied carbon in other ways. We have sponsored the development of a new tool called the Embodied Carbon Calculator for Construction, or EC3. Developed by Skanska in partnership with the University of Washington’s Carbon Leadership Forum, EC3 is an open-source tool running on Microsoft Azure which tracks the embodied carbon of raw building materials. With EC3, builders can compare levels of embodied carbon in various materials like concrete mixes—a comparison that up to now has been neither simple nor reliable. 

EC3 will enable a significant reduction of embodied carbon in upcoming projects, like the multi-year refresh of our Puget Sound campus, which broke ground recently. From Silicon Valley to Redmond and beyond, we are proud of the ways we’ve found to reduce embodied carbon, as part of our ongoing campaign toward more environmentally sustainable campuses.

Source: LinkedIn Pulse

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