When selecting sustainable building materials for a green project, natural stone seems like a no-brainer. However, if you factor in the quarrying and fabrication processes, its environmental impact may be closer to manufactured materials than one would think. That's why the Natural Stone Council (NSC) has spent the past year researching the “greenness” of natural stone.
“We talked with our customers and the design community,” says John Mattke, co-chair of the NSC and chairman of its Committee on Sustainability, “and what they all want is actual data for building a solid sustainable model for their projects. A lot of manufacturers are throwing out unsubstantiated claims about their materials' sustainability. In the midst of all this ‘green washing,' we want to speak with researched data.”
The NSC Committee on Sustainability worked with the University of Tennessee's Center for Clean Products to conduct the Natural Stone Industry Environmental Benchmarking Study. Tennessee researchers independently collected confidential survey data and compiled a life-cycle analysis of stone. “The research indicated that stone fares well in a long-term comparison with other materials,” says Mattke.
The following is an excerpt from the study's executive summary.
Characterization of Data
A total of 42 companies in the North American natural stone industry responded to the survey, submitting data for 64 quarries and 45 processing facilities. The data represents over 1.3 million tons of net quarried stone and nearly 0.49 million ton of net stone products from fabricators.
Responding in the greatest numbers were the granite (60%) and limestone sectors (25%). This response is not surprising as these types dominate U.S. stone production, according to the 2006 USGS report. A smaller portion of the responses were from sandstone (9.2%) and marble (4.6%) producers. Slate and travertine account for only a very small portion of the repliers.Quarry OperationsAdequate information has been collected to perform an initial life-cycle inventory for granite, limestone, and sandstone quarry operations.If the energy and water requirements for each extraction technique are significantly different, consumption per ton will vary by stone type.Since extraction technique varies by stone type, the use of certain materials, such as replacement parts, will likely vary with the type.Water consumption efficiency will be a key topic when discussing the sustainability profile of the natural stone industry due to the increasing global water shortages. It will also present a key opportunity for a best practice in the industry.Best practices may include a monitoring plan, as well as a remedial action plan.Identifying additional market niches or other uses for scrap stone is needed to overcome the aesthetics issue.Establishment of a corporate environmental policy for quarry closure throughout the industry may be warranted.