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from Natural Life magazine,
May/June 2009 Part Five: Materials and Resources Driving through a subdivision under construction can be a frustrating experience for anyone sensitive to the order of Nature. Generally, these sites are littered with partially used two-by-fours ready to be tossed into the already full dumpsters. The wind has strewn various types of discarded plastic that lay pinned by discarded particle board and all the vegetation has been removed. Well, that is changing because home builders can now achieve Leadership in Energy and Environmental Design (LEED) recognition. Only a few years ago, it was wishful thinking to imagine developers initiating the use of Forest Stewardship Council (FSC) certified woods, sourcing recycled content materials and training their contractors on proper waste management. In this article, I will discuss some of the minimum requirements – known as Prerequisites – in the Materials and Resources category for LEED certification. I hope these commonsense approaches will eventually become commonplace in all home building. Material Efficient Framing The Prerequisite calls for a ten percent reduction in waste as a minimum. This means that when the design calls for a joist to be twelve-feet, six-inches long and the standard lengths are twelve feet and fourteen feet, there is an automatic eighteen inches of wasted material unless it can be utilized somewhere else. This minimum requirement puts the onus on the designer and, in the case of custom homes, the owner as well. The added bonus is a ten percent cost saving in materials. To score any points in the category, a detailed framing plan becomes part of the drawing package and includes specific lengths of lumber along with a detailed cut list and lumber order. The alternative to this is to use off-site fabrication where saving materials through innovative methods of construction is how the company stays in business. Environmentally Preferable Products This is an interesting and progressive section of the LEED program that has
multiple benefits. Preferred products include three considerations: FSC
certified wood, local/regional materials and rapidly renewable materials. The builder must provide documentation that wood products were purchased from a supplier that has Forest Management Certification, which is the basic building block of the FSC system that verifies responsible forest practices. The emphasis placed on regional materials recognizes the social advantages to local purchasing as well as the environmental implications associated with transporting heavy building materials over long distances. LEED standards also include resource reuse of materials like steel, wood, concrete, brick and asphalt, which can be reprocessed for reuse. Recycled content is a growing industry. For example, ground slag from blast furnaces is used as aggregate in concrete, drywall is available with post-consumer paper and twenty-five percent recycled gypsum content, glass is being turned into counter tops and floor tile, and carpeting is being turned into new underlay and carpeting. Insulation, ceiling tile, waste wood and all metal products have a continued life cycle. It is now realistic that buildings use from seven-and-a-half to fifteen percent post-consumer products, thus reducing the use of virgin material and landfill. Rapidly renewable materials are defined as plants that can be harvested within a ten-year cycle. Certainly, bamboo is one such product, however it is not grown in all areas, whereas straw is more prevalent. Wheat straw and sunflower hulls are being made into doors and hemp stalks are converted into paint finishes locally. Poplar fits into this category and recently has become the preferred wood for trim. Other products include wool carpets, cotton bat insulation, linoleum flooring and bio-based plastics made from corn starch. Products with low emissions of volatile organic compounds are recognized as improving indoor air quality and are therefore also encouraged. That includes all sealers, primers, paints, coatings and adhesives. Solid colored finishes applied on-site off-gas more than light bases, with white being the lowest. Organic binders in composite woods are now available in cabinet materials, doors and trim. Waste Management The LEED Prerequisite here is for the contractor to investigate and document local options for diversion of all waste materials. This includes excavation material, metal straps, plastic and paper wraps, cardboard, beverage containers, scrap steel and wood. It is the general contractor’s responsibility to educate subcontractors in the importance of separation and location of recycling bins. The LEED goal is to divert twenty-five percent or more waste from landfill sites. Durable Building This category encourages the extended life of all products. For example, windows, exterior wall and roof finishes are available with fifty-year warranties, as opposed to the common ten to twenty-five. Equipment such as domestic hot water tanks are available with a twelve-year life expectancy instead of six. So the next time you hire a designer for a home building or renovation project, consider how conventional material sizes can reduce waste by ten percent. Ask your general contractor to incorporate a waste management plan, because a well planned project can divert seventy-five percent of waste from landfills. And, as we’ve seen, recycled content can reduce the use of virgin material. In addition, there are enough suppliers of “rapidly renewable materials” to meet at least five percent of your needs and fifty percent of all wood can be FSC certified. And don’t forget the positive economic implications of supporting local producers, craftspeople and suppliers. In my next and last column, I will be reviewing how indoor air quality contributes to the design and construction of a sustainable home. This is one of a limited number of articles from Natural Life magazine that are available for free. To read all of our current and back issues, subscribe to our online edition. |
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