Rethinking Construction: The Rise of Wood as a Sustainable Material

Innovations in Wood Reclamation and Recycling: Enhancing Environmental Benefits

Wood’s rising popularity as a construction material is largely due to its ability to sequester carbon. Being composed of about 50% carbon by weight, wood performs better than materials like concrete and steel in terms of carbon emissions. This significant carbon storage potential has driven the recent growth in timber construction.

However, achieving environmental benefits from wood requires careful consideration of its entire life cycle. Wood can only serve as an effective carbon sink if it remains intact and does not rot, burn, or deteriorate. While some issues, such as fire, may be unavoidable, others are preventable.

A major issue is the amount of wood that ends up in landfills. According to National Waste Associates, wood is the second-largest component of construction and demolition (C&D) waste, following concrete. Unlike concrete and steel, which are recycled at relatively high rates (98% and 82%, respectively), a significant portion of C&D wood waste is discarded and sent to landfills. This discarded wood eventually decomposes and releases its stored carbon, negating the benefits of using wood initially. Many design teams do not account for this potential carbon release in their projects.

One reason for the high volume of discarded lumber is the labor and cost involved in repurposing it, such as removing nails or staples. Urban Machine, based in Oakland, CA, is addressing this issue with a novel material reclamation process. Using artificial intelligence and robotics, the Urban Machine processes dimensional lumber by employing computer vision to detect and remove fasteners, preparing the wood for reuse in new construction.

This technology offers a localized solution, as the machine can be rented and used on-site, allowing wood from a project to be repurposed either within the same project or for future needs. It accommodates various types of lumber, including heavy timber, glulam, and dimensional sizes ranging from 2×4 to 6×18.

The Vibrant Cities Lab, founded by American Forests, the USDA Forest Service, and the National Association of Regional Councils, provides resources for managing urban forests and enhancing socioeconomic and environmental outcomes. Their Urban Forestry Toolkit offers a comprehensive approach to green infrastructure management.

One of the Vibrant Cities Lab’s resources, the Urban Wood Reuse Action Guide, advocates for deconstruction over demolition. Deconstruction enables the careful salvage of reusable materials, creating jobs and generating revenue, unlike the more destructive and less selective process of demolition.

The Lab also identifies additional sources of reclaimed wood, such as municipal waste and wood from urban tree pruning. Municipal wood waste constitutes about 17% of total municipal waste, while pruned urban trees represent nearly 30% of annual hardwood consumption in the U.S.

InventWood, based in Frederick, Maryland, is pushing the boundaries of wood technology with innovations like wood honeycomb, transparent wood, and insulating wood. Their flagship product, MettleWood, aims to replace steel and concrete in construction. By removing lignin from wood and compressing the remaining material, MettleWood becomes 50% stronger, 80% lighter, and less expensive than steel. It also boasts a Class A fire rating, a first for a 100% wood product, and can be made from various wood types, including fast-growing and invasive species.

If scalable and low in embodied energy, such technologies represent a significant advancement in upcycling. They transform common, often undervalued materials into highly efficient alternatives, potentially enhancing the environmental performance of the built environment. This approach could redefine how we view and utilize waste, pushing it to exceed the performance of traditional virgin materials.