Find out the answers to questions about PEX tubing, finishing an attic in a bungalow house and stucco.
Stucco provides a long-lasting and durable finish, according to Eco-Expert David Johnston. The drawback is the amount of embodied energy it requires to produce.
Introducing the eco-experts
Natural Home is thrilled to introduce a new, active Editorial Advisory Board, a collection of some of the best brains we’ve ever encountered. Natural Home—and its readers—are incredibly fortunate to have attracted the enthusiasm of these pioneers in the healthy building and living industries.
Beginning with this issue, a rotating panel of our board members will answer reader questions in this department. “Eco-Expert” Debra Lynn Dadd, who remains a valued board member, will continue to answer questions and will also begin contributing feature-length articles.
Edith Vanderbilt Cecile is involved in several green interior design and sustainable garden projects. As the director of Concurrent Technologies Corporation’s Washington, D.C., operations she has managed several international environmental projects. She is the founding executive director of the United States Environmental Training Institute (USETI), a nonprofit organization that promotes appropriate environmental technologies and management approaches by working with industry and government organizations in developing countries.
Called “the queen of green” by The New York Times, Debra Lynn Dadd is the author of Home, Safe Home as well as Nontoxic & Natural; The Nontoxic Home; Natural & Earthwise; The Nontoxic Home & Office; and Sustaining the Earth. Debra believes that “a natural home should be about living as nature, in nature, rather than solely using natural materials.” She explains, “We need to learn about our places first, and our homes need to arise from the unique individuality of living in our places. We’re still separate for the most part. This is the next step.”
Brian Dunbar, idec, NCIDQ, Associate AIA, is director of the Institute for the Built Environment and associate professor of construction management and technology at Colorado State University. Brian has participated in green building research with the American Institute of Architects, the U.S. National Park Service, the U.S. Forest Service, and numerous school districts. He is a member of the AIA’s Committee on the Environment and the National Trust for Historic Preservation. His approach to sustainable building is broad, including land developments, embodied energy, pollution prevention, reuse and recycled content of materials, site and landscape design, historic preservation and restoration, indoor air quality, handwork, local art, natural lighting, life-cycle costing, and aesthetics.
David Eisenberg is co-founder and director of the Development Center for Appropriate Technology in Tucson, Arizona, an organization supporting the development and use of sustainable solutions to human and ecological needs. A co-author of the best-selling book The Straw Bale House, he has also built rammed earth and adobe homes, led workshops and consulted on alternative building materials and building codes, and oversaw construction of the spaceframe and glazing systems for Biosphere 2 in Oracle, Arizona. He is leading a broad-based collaborative effort, Building Sustainability into the Codes, with the goal of creating a sustainable context for building regulation. David is a member of the U.S. Green Building Council Board of Directors, where he is co-chair of the Greening the Codes Committee, vice chair of a subcommittee developing standards for earthen building materials, and serves on the Tucson/Pima County, Arizona, Joint Building Code Advisory Committee.
Pliny Fisk and Gail Vittori are the co-directors of the Center for Maximum Potential Building Systems, a green building think tank in Austin, Texas. They are working with the Department of Energy’s Building America program and with the Environmental Protection Agency to develop software that helps builders and homeowners determine the impacts of the building materials they choose. Pliny and Gail are at the cutting edge of adaptable design and understanding our human footprint. “Ideally, a lot of what we’re trying to do is make the invisible visible,” Pliny says. “Because it’s not that we’re bad people; we just don’t understand the full impact of our choices.” Adds Gail, “You as a purchaser, builder, or designer have opportunities to make a big difference.”
Steven Foster is president of Steven Foster Group, specializing in medicinal and aromatic plant photography and information resources. He is also an international consultant and lecturer. Steven is the author of fourteen books, including the award-winning 101 Medicinal Herbs, and three Peterson Field Guides, most recently A Field Guide to Western Medicinal Plants and Herbs (with Christopher Hobbs), released in April 2002.
David Johnston, president of What’s Working, an international environmental design and consulting firm in Boulder, Colorado, that specializes in environmental construction technology, has been advising Natural Home since its inception. “In the early days, it was far ahead of its time,” he says. “Today, green building and natural home-styles are increasingly becoming mainstream. It’s been an honor and pleasure to watch the transition.” Co-author of the Denver Metro Home Builder’s Association Green Builder Certification Program, David also has developed green builder programs for Boulder and Aspen in Colorado, the city of Los Angeles, and the East Bay area of San Francisco. His firm developed a marketing strategy for the U.S. Green Building Council to introduce the nation’s first commercial building environmental rating system, Leadership in Energy and Environmental Design (LEED). He is the author of Building Green in a Black and White World.
David Pearson, riba, is an architect and the author of The Natural House Book, published in 1989, which was one of the first books to introduce mainstream audiences to natural building. A promoter of Gaian thinking (“everything we do affects the health of the whole planet”), David’s work focuses on three touchstones that buildings of the future need to integrate: environmental awareness, healthy, sustainable materials, and a deeper understanding of the spiritual side of the home. He has also written The Natural House Catalog, Earth to Spirit: In Search of Natural Architecture, New Organic Architecture: The Breaking Wave, and The House That Jack Built series for Chelsea Green. He is the founder of the United Kingdom-based Ecological Design Association and a founding member of Gaia International, an informal think tank of European eco-architects. David would like to see Natural Home put “less emphasis on building natural homes on fresh land” and pay more attention to neighborhoods—broadening the concept of the natural home to include community and urban living, including affordable housing and apartment dwelling.
Sarah Susanka, AIA, is a residential architect with more than twenty years’ experience. Her books, The Not So Big House and Creating the Not So Big House, have sold more than 500,000 copies and spawned a major movement toward smaller, but better quality, home design. This fall she will release a third title, Not So Big Solutions for Your Home. Sarah also maintains a vibrant and heavily visited website, www.notsobighouse.com. Her current crusade is to integrate sustainable design strategies into the built environment in a way that everyone can grasp and implement. “There’s a lot of lip service and a lot of good ideas,” she says, “but they are still far from accessible for the average person.”
Carol Venolia has spent thirty years pursuing her fascination with how buildings relate to living things—something she believes most contemporary buildings do poorly. Her Natural Home column, “Design for Life,” explores how we can understand our role in the biosphere by the way we design and inhabit our homes. As an architect, Carol has designed homes of straw, earth, and wood, and consulted on the design of schools, healing centers, and eco-villages. Her book, Healing Environments: Your Guide to Indoor Well-Being, looks at how our personal environments can increase our vitality by bringing us closer to our natural state. “We need to understand that the buildings we inhabit can help us cultivate an understanding of human life as interconnected with the rest of the biosphere—the real point of power for planetary healing,” she says. Past projects include publishing Building with Nature newsletter and co-founding the Natural Building Network.
Questions for the experts
I recently read about the use of PEX tubing (the kind used in radiant floor installations) for supply-line use. The article also mentioned that PEX is currently being certified for this use in many states. What are your views on the health and environmental aspects of this new product?
—Paul, via e-mail
Debra Lynn Dadd replies:
PEX is an acronym for “cross-linked polyethylene” plastic. The “PE” refers to polyethylene, the raw material used to make PEX. The “X” refers to the cross-linking of the polyethylene across its molecular chains.
PEX is used to make coiled tubing for plumbing installations and was first introduced to the European floor heating market in 1972.
Because polyethylene is a thermoset plastic, the molecules are bonded so tightly together that it is difficult for them to separate and vaporize, as do other types of plastic. PEX’s advantages over metal pipes include flexibility (making installation easier), extreme durability within a wide range of temperatures and chemicals, and resistance to corrosion.
There are several types of PEX tubing on the market, each cross-linked using a different method. In the Engel method of manufacturing PEX, polyethylene is chemically cross-linked with peroxide, providing a perfectly uniform product. Two other common methods of cross-linking PEX are the Silane method, which uses a warm bath, then flushes the tubing to remove contaminants, and the Radiation method, which uses electrons that bombard the tubing after it has been extruded.
Polyethylene is considered nontoxic, and because of the tight bonding, it is likely that all PEX plastics would be nontoxic as well. However, studies are under way to determine if PEX can add any pollutants to the water. Environmentally, all plastics are made from nonrenewable petrochemicals. They are polluting in their extraction and manufacture and are also not biodegradable. In contrast, although copper causes pollution in its mining and manufacture, used copper pipes can be melted down and the copper reused indefinitely.
Bundling up the bungalow
I have a 1926 bungalow and want to finish the attic. The original Arts and Crafts influence plus a responsible past owner has ensured that the house was built with good materials and is in good condition, but I would also like to make future choices as green as possible. I want to finish the attic into one large room. First, I need to insulate the roof between the rafters, but because I am in the Midwest, I want to have a relatively high R-value. So far, blow-on polyfoam that hardens is the only option I have found that can utilize the existing two-by-six-inch rafters and still achieve R-30 or higher. The product information says there have been great improvements in eliminating toxic outgassing, but I’m certain it is not biodegradable.... Plus, it's expensive. Can I get a high R-value insulation that fits within the existing rafters and be green, too? If so, can I afford it on a modest income?
—Lynn Amlie, Iowa City, IA
Pliny Fisk and Gail Vittori reply:
The challenge for this job is fulfilling the energy performance objectives with a green insulating material. Given the existing structure and the R-30 requirement, only polyurethane foam will work. We suggest the following three-phase, whole system strategy.
Weatherization: Because the house is old, leaks and windows are probably your biggest problem. Ask your local weatherization service to check them with a leak-snooping detector, then obtain a caulk that has few or no volatile organic compounds (VOCs) and start fixing the leaks, or have the weatherization service do this.
Weatherizing all of your windows is important, but doing so without destroying the beauty of the bungalow style could be tricky. Weatherizing usually involves installing an extra pane on the outside that you can remove when warm weather arrives. Glass is preferable, but acrylic is the best plastic option if you must have something lightweight. Both options can be locally manufactured into frames to avoid the energy costs associated with transportation. We would suggest a brown anodized aluminum frame—brown will suit your aesthetic needs, and aluminum offers the benefit of high recycled content.
Whether you have air-conditioning or not, grow native plants on the east and west sides of your house to block the sun.
Attic Modifications: If possible, shut your attic off seasonally from the hot air rising in the winter—you will probably get enough heat through the floor (unless it is built very tightly) or any door that might be used to block the stairway. In the summer, encourage the chimney effect through the stairs and out through the highest venting (opposite side) window (you might even consider installing a vented skylight because the chimney effect really works).
Extend the joist depth by screwing two-by-fours into them so that you can use a green, nontoxic, non-petroleum-based insulation. If you use cotton insulation, which now comes in batts with mesh backing, you must increase the depth to equal about nine to ten inches. Then put up a vapor barrier and finish out with some great recycled wood.
Financing: This might be your biggest hurdle if Iowa lacks conservation tax incentives, though your local utility provider may offer something. If they don’t, the next alternative is the bank, which probably has good rates on weatherization and/or home improvement loans. Usually your loan payment will be less than your winter utility payment savings, but you can do the approximate math with your utility or weatherization consultant.
Exterior stucco finishes
We recently bought a home that was built in 1946 of cement block and covered with aluminum siding in the early ’70s. There is no insulation between the cement block walls and the siding. Our home inspector recommended that we look into synthetic stucco finishes that can be applied directly onto rigid insulation. We are considering this as a method of making our home more energy efficient, as well as low maintenance, as it won't require painting. Is this an environmentally sound choice, compared with covering insulation with siding that is wood or cement-based? I can't find information on the toxicity of the product—in manufacture, application, or finished product.
—Shari Lewis, Arlington, VA
David Johnston replies:
First of all, please recycle the aluminum siding. It has a great and illustrious future ahead! As for your question about stucco, there is a difference between real stucco, which is primarily concrete and troweled into place, and synthetic stucco, which is typically sprayed onto a foam substrate.
Either type can be applied over rigid foam. You are fortunate to be in the D.C. metro area, where there are still good craftspeople who know how to do real stucco correctly. The biggest issue in Virginia is moisture—you are changing the fundamental energy and moisture dynamics of your house by insulating the concrete masonry unit (CMU) walls and putting a moisture barrier on the outside. You have several considerations in the design.
• Use closed-cell rigid-foam or extruded polystyrene board (usually used for foundation insulation). It should be at least two inches thick. White Styrofoam, the stuff coffee cups are made from, absorbs moisture. You want to keep the moisture outside the foam. Extruded polystyrene does not absorb moisture and is often molded with a tongue-and-groove edge that also helps keep moisture out.
• Seal the joints between the sheets of insulation with tape used for housewrap. This creates a moisture plane behind the stucco, so any water that gets past the stucco has a place to run down rather than getting into your walls.
• The stucco should be layered onto wire mesh. The mesh can be attached with spacers to hold it one inch away from the foam. This helps with drainage.
• The finished stucco will provide a long-lasting and very durable finish. The only environmental consideration is that cement production is energy intensive at the factory. Eight percent of the carbon dioxide released into the atmosphere worldwide is from cement production. Having said that, I think that when a material is used to provide a long-term solution such as stucco, it has justification as a green material.
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