Demolition of obsolete buildings is critical to the construction industry. Traditionally debris is dumped in landfills. Steel-construction buildings can yield significant quantities of metal for recycling but in most cases, especially smaller structures, the bulk of debris is carted off to landfills. Estimates suggest that building waste comprises most of the material in landfills. Greater environmental awareness and stricter environmental laws are rendering demolition and landfill less acceptable. "Green Hybrid Deconstruction" (GHD) is a method of disassembling structures for materials reclamation. GHD uses heavy machinery to remove large sections of buildings which are processed by human labor to retrieve lumber and re-usable materials for resale. By our estimates 30-50% of the structures' materials, mostly lumber, can be reclaimed. Organic material such as wood rots anaerobically in landfills forming methane, a more potent greenhouse gas than CO_2. Reuse of materials also takes pressure off of existing raw materials sources. For example, a rough calculation shows that and average two-storey urban house in Buffalo NY contains about 50 tons of lumber - the equivalent of about six, old-growth (32' usable trunk, 3' diameter at breast height) hemlock trees. In our experience with deconstruction of small structures, GHD costs 5-10% more than traditional demolition due to increased time and labor needs. Material sales, which range widely in cost, recover less than 30% of the deconstruction price. Other challenges to using GHD include how to gain acceptance for wider use. Simple innovations such as mechanized de-nailing and programs to certify reclaimed lumber would greatly increase its use.
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