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How LEED Certification Works

More LEED Categories

Recycled Carpets
What is recycled carpeting? According to, recycled or PET (polyethylene terephthalate) carpet is "manufactured with yarn created from reclaimed polyester resins of two-liter soda bottles and ketchup containers."

Materials and resources
Using recycled materials in a home requires some investigation, requiring you to ask about products you might not be familiar with. While many people feel comfortable researching refrigerators, deciding whether to use plastic or real lumber can be a little more daunting. LEED notes that many of these products -- like linoleum flooring -- were once considered inferior, but they've made aesthetic strides in the past few years.

  1. Use less lumber and try modular framing and materials.
  2. Use salvaged, reused or wood-alternative flooring and walls, and products with low VOC (volatile organic compound) emissions. Avoid tropical rainforest wood products. Try synthetic materials like linoleum flooring and composite decking, renewable resources like bamboo and jute, and recycled carpet -- either PET (see sidebar) or carpet with reused backing.
  3. By using products manufactured within the region, you'll further cut down on pollution from transportation.
  4. Reduce job-site waste to no more than 2.5 pounds per square foot of floor area by recycling or reusing wood, drywall, metal and cardboard.

Indoor Environmental Quality
There are a number of culprits that increase indoor air pollution, including poor ventilation and high temperature and humidity levels. The exposure to poor air quality can increase long-term health problems like respiratory and heart disease.

  1. Using a moisture-control, heating, cooling and ventilation system -- like Energy Star's Indoor Air Package -- can prevent mold, pests and airborne pollutants.
  2. Ventilators for fireplaces and stoves remove toxic gases from the interior of the home. And you can install carbon monoxide detectors, which start around $20.
  3. Install a humidity control system -- use a humidifier in dry climates and a dehumidifier in wet climates.
  4. Use an outdoor air system to ventilate indoor air. You can purchase specific devices to filter the air as it's entering your home, or you can open a few windows.
  5. Install exhaust fans in kitchen and bathrooms to reduce pollutants and moisture.
  6. Design your air-duct system so air flow is evenly distributed among rooms.
  7. Install air filters. Mechanical, electrical and ionic air purifiers are available, with a wide range of prices.
  8. You can protect indoor air quality from outside contaminants with permanent walk-off mats (which are larger and more durable than traditional door mats) and central vacuum systems. If you're in the design stage of building a home, LEED recommends including a space at the entrance for removing and storing shoes to prevent bringing outside contaminants into the home. Flush the house of construction contaminants by running the HVAC system fan for one week while the windows are open.
  9. Seal the foundation of the home and install a radon detector. Every state has a regional EPA office, which can help you find a qualified radon testing company.
  10. Seal an attached garage (and the carbon monoxide emissions from cars) from the home by painting the garage walls (carbon monoxide can penetrate unfinished drywall) and installing weather stripping around the doors.

Innovation and Design Process
This group has to do with educating the consumer and design innovation --it's really for new homeowners who want to make a long-term investment and get LEED certification.

  1. Use a team of architects, energy engineers and land planners and implement performance testing. An energy engineer, an architect and a land planner, for example, can work together on how to place solar panels on a house without making it unattractive.
  2. Use high-quality, durable materials according to your specific area's needs for the foundation, exterior walls, roof, air sealing and mechanical systems.
  3. Get creative and go above and beyond LEED standards for bonus points. (You'll need to contact LEED to see if your ideas qualify.)

Finally, your builder should provide you with a LEED for Homes rating certificate, the completed checklist and general guidance for equipment and appliances, as well as a walk-through before completion.

" class="ListParagraphCxSpLast">To learn more about LEED certification, check out the links on the next page.

Related HowStuffWorks Articles

More Great Links


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  • Gunther, Marc. "Who's The Greenest Bank Of All?" Fortune, Sept. 17, 2007.
  • Home Energy Magazine.
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  • Kamenetz, Anya. "The Green Standard? LEED buildings get lots of buzz, but the point is getting lost.", October 2007.
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  • Living Homes architectural firm.
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  • "The Greenest House on the Planet." Business Week, Sept. 11, 2006.
  • Tibbitts, Tim. "Advocates say green buildings cut costs, improve work environment." Crain's Cleveland Business, October 16, 2006.
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  • United Nations Environment Programme.
  • U.S. Department of Energy.
  • U.S. Environmental Protection Agency.
  • U.S. Green Building Council.
  • Whole Building Design Guide.