THE NEW GREEN HOME
Rehabbed, recycled and resourceful
Cotman's future green home stands on Appleton Street in Cambridge, right in the heart of an oldcity neighborhood. (Easy walking distance to downtown will make the occupants less dependenton cars.) A three-story, drafty wood-frame, the house was a poorly insulated energy hog withsome hazardous lead-paint-covered walls.
The overall conception is to rehab the 1928 structure for the future, but with off-the-shelfmaterials. The architects' plan also reinforces the neighborhood's historic identity, preserving theArts and Crafts style of the house.
With regard to structure, the Cambridge House designers discovered that many of the 1920s-eramaterials in place were actually less toxic than their modern counterparts. Thus they preserved suchmajor features as the foundation, side walls, hardwood floors and roof and wall shingles.
The following checklist gives advice from professionals and examples from the Cambridge andother houses on how to start drawing up your own green blueprint.
CHECKLIST:How to Get Started
Healthy House Checkup
Start by identifying such pollutants as: emissions from improperly vented gas or oil appliances; mildew and mold; VOCs from plywood, adhesives, wallboard, cabinetry, carpeting, flooring, foam and upholstery. (Older materials are safer - after five years most VOCs will have outgassed completely.) Test for asbestos, radon, and lead from old wall paint.
If you are building from scratch, you want to start with a north-south orientation, with many south-facing windows to capture solar energy. Take a cue from your surroundings: use native stone or wood and you'll save shipping costs and energy while staying faithful to your landscape. Make sure your floor plan follows the local topography and preserves trees and wildlife habitat.
Check your site's proximity to potential problem areas: for example, chemical leaks from underground gasoline tanks or landfills; facilities likely to be sprayed with pesticides, such as golf courses; and sources of electromagnetic radiation, such as high-voltage lines.
Foundation and Moisture Protection
If you can, reuse an existing foundation. If not, look into a more environmentally sound, lighter-weight, aerated concrete, such as Faswall. Conventional foundation waterproofing sealants emit VOCs; have your builder use safer alternatives, such as Dynoseal (for the exterior; subterranean foundation) and Penetrating Water Stop (for the interior face).
Insulation poses a multitude of environmental dilemmas, whether it's an ozone-depleting foam or a fiberglass that outgasses formaldehydes and releases particulates. The Cambridge House will be insulated with blown-in recycled newspaper. Paul Novak of Environmental Construction Outfitters recommends recycled cotton insulation or low-E radiant barrier made of microcell polyethylene core sandwiched between sheets of reinforced aluminum foil. Because the cotton is treated with fire retardant chemicals, you might want to use a non-VOC sealant on the walls.
Check your house for leaks. The Cambridge House will be tightened up to require less energy. The architects decided to "pop out" the attic, building the house higher to capture more solar energy. Photovoltaic panels store electricity. Solar hot water heaters are retailing now for as low as $2,000 with installation. At Cambridge House, a ground-source heat pump will tap into a geothermal well beneath the house, providing energy for winter heat, cooling in the summer, and hot water year-round. It costs $5,000 - about 20 to 25 percent more than conventional energy but it will pay for itself through savings in five to six years, Cotman says.
Ceilings and Flooring Plywood - used both in interior walls and in sub-floors and particle board contain toxic binders and glues. If you can't find affordable all-natural, untreated wood, seal in those VOCs (ECO recommends Safeseal). Avoid veneers made of tropical forest species. The safest floorings are natural (not vinyl) linoleum and cork, untreated hardwood, ceramic tile, marble and slate. Big City Forest, in New York, makes flooring from reclaimed wood.
Framing lumber conventionally comes from such old-growth species as Douglas fir and white pine, which are dwindling rapidly. Turn to cheaper spruce, especially local, domestic species, and use lumber from woods deemed "sustainable" by reputable certification groups, such as Scientific Certifications Systems. If you're worried about termites, have your lumber treated with Timbor; a low-toxicity boric acid product.
The safest roofs are probably cedar shingle or metal, according to ECO. You can also use aluminum made from recycled beverage cans; slate shingles; or galvanized steel molded to look like tiles. Recycled asphalt shingles may outgas petrochemicals downwards (as well as up).
Low-flush toilets use half the water of conventional ones. To conserve "drinking water that for the most part gets flushed down the toilet," Cotman is installing composting toilets (a good brand is the Clivus Multrum) and low-flow faucets and showerheads.
The Cambridge House will also have an innovative "greywater" system, in which wash water goes to gardens or is recirculated to the house's indoor plants, which oxygenate and filter impurities from the air. Cotman is working with Home Depot and the plumbers' union to cut the costs of greywater systems for future consumers.
Another new option: with a revolutionary rainwater collection system, the updated-traditional Florida "Cracker" House in Sarasota draws 40 to 60 percent less from the public water supply than the conventional home does.
A good "solid block" carbon filter can be attached to your sink's plumbing and will remove chlorine, most bacteria, parasites, chemicals and most heavy metals.
One of the most important air-quality steps for the Cambridge house will be a built-in heating, ventilation and air conditioning (HVAC) system. But remember: no ventilation system can replace such simple details as windows that can readily be opened and closed. Whole-house ventilators cost about $700; $3,000 with duct work and labor, according to Your Natural Home.
Look for energy-efficient (R-5 or R-6 rating; most windows have R1) and low-emissivity windows with a coating that reflects heat but lets in light (ask for low-E, or heat-mirror windows). Don't use polyvinyl chloride (PVC) window frames. Dioxins are released during the production and incineration of PVC.
Floor, Wall and Other Surface Finishes Use low-VOC and low-toxic finishes, such as water-based Skanvahr, on drywall and flooring. If you're not allergic to them, natural resins and beeswax products, natural shellac and linseed oils or Tung oil are additional less-toxic, if more expensive, alternatives.
Pipes and Plumbing
Replace lead pipes and soldering. For new pipes, use copper pipes and intakes, not PVC.
Written by: Francesca Lyman
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