This green-built house has rigid foam insulation in the walls an
Building green? Here are the key sustainable building materials you need to do the job right. If you’re a builder who’s new to green building, take heart. Most of the practices are common sense, the materials are becoming readily available, and construction site waste disposal can be almost as simple as using a system of recycling bins at home.
1. Start With Insulation. “Making sure that your envelope is well insulated is your cheapest and best return on investment,” says Tucson, Arizona-based green builder and solar pioneer John Wesley Miller. Miller used polyisocyanurate (closed-cell) foam insulation wrapped around the outside of concrete-filled, masonry block walls and covered the insulation in three layers of stucco in the Vision House® Tucson, shown here,
which he built as part of the Green Builder Media series of demonstration homes. Closed-cell spray foam insulation is also used in Colorado by Boulder, Colorado-based green architect and builder Scott Rodwin, AIA, LEED AP, as well as by Boulder-based sustainable architect Timothy J. Laughlin, AIA. Closed-cell spray foam delivers a high R-value, creates an effective air and vapor barrier and doesn’t settle or sag. On the down side, it’s also denser and more expensive. And according to Austin, Texas-based sustainable architect François Lévy, AIA, closed-cell foam is probably not appropriate for climates like Austin’s because, under certain psychrometric conditions, it can serve as a moisture dam, trapping condensation in the wall and inhibiting the drying process.
Other types of insulation considered green for their energy-saving properties include open-cell spray foam and spray-applied cellulose insulation. Open-cell spray foam provides a good air barrier (but not an effective water vapor barrier), is often used for interior walls, and is less expensive than closed-cell foam. Spray-applied cellulose insulation offers a good R-value, fills in crannies, and is a less expensive option.
2. Install high-performance energy-efficient windows. Rodwin typically uses double-paned, low-E windows with a Cardinal 366 (or equivalent) film. Miller used MI EnergyCore dual-pane, low-E vinyl windows in the Vision House Tucson. According to Lévy, the City of Austin adopted the International Energy Code and non-thermally broken aluminum windows are not allowed. As Laughlin points out, “High-performance energy-efficient windows give us more freedom to provide what clients want, to let the outdoors in, without sacrificing too much in terms of either heat gained or loss, depending on the climate.”
3. Employ the most effective, super-high-efficiency heating and cooling system for your climate. According to Rodwin, in dry climates like Boulder’s, evaporative coolers provide very efficient cooling, and ground source heat pumps can be a good choice for clients that need heating and cooling and can afford the cost. Miller installed Rheem’s net-zero HVAC and solar water heating system in the Vision House Tucson. Radiant heating systems are also worth considering. Laughlin utilizes them, although Miller doesn’t, and Rodwin says that high-efficiency forced air systems can be as efficient at a lower price.
4. Install water-efficient plumbing fixtures and energy-efficient hot water heating systems. Make use of dual-flush low-flow toilets, water-saving sinks and faucet aerators, and energy-saving hot water heating systems, and encourage your clients to choose water-efficient, Energy Star-rated appliances.
5. Utilize LED lighting. “It’s a great thing,” Miller says. “It doesn’t get hot, and we’re installing it in all of our new homes now.” Rodwin agrees. “Typically 95 percent of the lighting in our homes is high-efficiency,” he says. “We are phasing out CFL’s due to the mercury, poor color rendition and poor dimming capability.”
6. Reduce air infiltration and provide fresh air ventilation. When you seal up a house tightly, you need to provide mechanically tempered make-up air, Rodwin says. While Rodwin, Laughlin and Lévy favor using heat recovery ventilators, Miller utilizes a system in which fresh air is introduced into the home as part of the HVAC system.
7. Limit or eliminate VOC materials, paints and coatings. “That new house/paint/carpet smell is the off-gassing of carcinogenic volatile organic compounds (VOCs),” Rodwin says. All of his clients prefer low-VOC products, and some clients require zero-VOC products where possible. “Products that contains formaldehyde (cabinets, nylon carpeting, adhesive, plywood, OSB, vinyl, paint, plastic, sealant, stains, etc.) off-gas VOCs,” he says. Miller adds that new furniture and material drapes can also off-gas VOCs, and his company no longer uses material drapes in its new homes.
8. Utilize local materials. Our experts use as many local materials as possible. “We source most of our stone from local quarries, landscaping is typically xeric or dry (requiring little moisture) or native, and we have been using beetle-kill pine (blue-stained wood) for flooring, trim, siding and cabinets,” Rodwin says.
9. Preserve mature trees. Mature trees can help shade the structure, Laughlin says, and they contribute to the value of a site, Rodwin adds. Miller agrees. “When we buy a lot for a client and lay out the house, we’ll move the house if we have to in order to save a tree,” he says. And some cities have ordinances to protect trees. “The City of Austin vigorously enforces a heritage tree ordinance to protect trees over 19 inches in trunk diameter,” Lévy adds.
10. Use reclaimed wood where appropriate. While reclaimed wood is often not acceptable for structural use in new homes, it can be used for features where structure is not an issue, Miller says. It adds texture and character and can be used for siding, flooring, countertops, mantles and furniture among other things, Laughlin adds.
11. Reduce construction site waste. Reducing construction site waste is good for builders and the environment. Lévy recommends utilizing advanced framing or optimum value engineering (OVE) framing techniques that cut down on lumber usage and waste generation during home construction such as BMC’s Ready-Frame™ framing products, which are delivered to the jobsite pre-cut and pre-built. Jobsite recycling is also important.
Consider setting up separate dumpsters for wood, cardboard, metal, and landfill materials, or hiring a waste disposal company that sorts through the dumpster and separates and recycles the contents. When it comes to building green, Miller believes that the key is to build houses in such a way as to minimize the need for energy in the first place. He also believes it’s possible to make a profit while doing this. “Builders still need to make a profit,” Miller says. “But, we also need to build better housing stock to leave the planet better than we found it."
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