GREEN BUILDING MATERIALS
By Michael Garrison, Professor of Architecture
The University of Texas at Austin
Used with permission
Green building strives to meet today's needs for shelter and work without depleting resources for future generations. Practicing resource efficiency makes it possible to reduce the pressure than construction places on natural recourses. Currently, according to the National Center for Appropriate Technology, construction and operating buildings consumes more materials and energy than any other single activity in the United States. Green building materials involves choosing building materials that use the least amount of energy to manufacture or produce, are the most likely to be recyclable or are already recycled, and are produced from an easily renewable resource. Green building products and methods do more with less: they are derived from reused salvaged, currently underutilized or waste materials; they reduce resource use; and they produce less pollution and waste than conventional building materials and technologies.
Depending on the criteria for a particular project, natural materials, recyclable materials, renewable materials, local materials, non-toxic/ low toxic materials, and materials that are in harmony with the environment can be considered green building materials. Wood should be specified from certified, well-managed forests. Alternatives to old-growth lumber include component systems (such as trusses and pre-manufactured), stressed-skin insulating-core panels or structural insulated panels, reclaimed wood, and composition materials (where recycled plastic is mixed with wood fibers). In addition, optimum value engineering techniques --including advanced framing systems, detailing for durability and job site waste management should be considered and implemented when possible. Other natural materials include plastered straw bales, rammed earth, adobe, and local stone.
Some green building materials take advantage of recycled products currently on the market: such as cement from fly ash, fiberboard from cardboard, tiles from recycled glass, carpet from recycled plastic, siding from recycled metals, piping from recycled plastic, landscape timber from recycled fiberglass, and roof shingles from recycled plastic are just a few of the building materials now available. Durable building materials offer greater opportunities for reuse: Stone and brick from a deconstructed exterior wall, for example, can be used as a durable paving surface.
Plastic is one recycled material that requires significantly less energy to remanufacture it into a reuse material than the energy required to produce the virgin plastic in the first place. Producing a plastic product from scrap plastic instead of virgin resin saves between 85%-90% of the energy otherwise used to produce the virgin resin in plastic. Plastic also constitutes one of the fastest growing categories of material used-and disposed of-in our economy. Today plastic comprises about 8% of the weight and nearly 30% of the volume of a typical municipal solid waste stream. Every year, we make enough plastic film to shrink-wrap the state of Texas. Plastic is therefore, one of the materials with the greatest potential for making it into reuse products. The use of plastics in building is relatively new. In 1985 the building industries consumed almost 10 billion pounds of plastics. The industry consumed over15 billion pounds of plastic in 2002, in the form of: pipes and fittings, plumbing and bathroom fixtures, interior and exterior building finishes, trim material and other uses. Products made from recycled Polethylene terephthalate (PETE) include carpets, insulating materials, containers, liners and industrial paints. High-Density polyethylene (HDPE) is characterized by its rigidity, low cost, ease of forming and resistance to breakage. It is used to make industrial pallets, bathroom stalls, plastic lumber and decking. Polystyrene (PS) is a versatile resin with a range of physical properties that include thermoforming-an ability to form and foam, which have applications in the building industry for use as insulation and as permanent insulated concrete wall forms.
When possible, local green building materials should be specified to reduce the transportation costs associated with using materials afar. Materials should be tested to make sure that they are low in volatile organic compounds and other, toxic substances, and that any waste run-off or emission associated with the production or use of the material will not harm the local environment or inhabitants. Choose building materials that do not out-gas harmful chemicals when they are hot and/ or wet. Moisture should be controlled to reduce mold and mildew growth and the deterioration of building materials due to these organisms.
Each material carries its own set of environmental burdens and benefits, and accurate information on this can be hard to find. The American Institute of Architects (AIA) Environmental Resource Guide (ERG) is probably the most detailed reference available on the environmental impact of building systems and materials. The Guide to Resource Efficient Building Elements, 5th Ed. available from the Center for Resourceful Building Technology in Missoula, Montana, contains this kind of product information along with manufacturer contacts, for everything from foundations to roofing. The Harris Directory in Santa Fe, New Mexico is a database available on diskette; it contains information on recycled content and resource-efficient materials. GreenSpec by Kalin Associates of Boston is a database of green products and practices, and technical language for them so they can be included in architectural specifications. The U.S. Green Building Councilís Leadership In Energy & Environmental Design (LEED) workshops and the Austin Green Building Program: Sustainable Building Sourcebook are both excellent resources. Finally, Environmental Building News is a monthly newsletter for builders and architects with an extensive database on green building materials.
www.greenbuilder.com
"When the last tree is cut, the last river poisoned, and the last fish dead, we will discover that we can't eat money." - Greenpeace
