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Healthy House 1997The Project | Features | For Sale | Sponsors | Pollutants | Resources FeaturesThe three keys to a healthy indoor breathing environment are air tightness, mechanical ventilation, and pollutant source control.
When we built Healthy House, we created an air-tight envelope for energy efficiency and complete control of the indoor environment. Then we made sure that every room of the house receives a constant supply of fresh, clean air while the stale air is re- moved. And, as a final step, we took care to make sure that the materials we used to construct the house and finish the interior, as well as the furnishings and products we put in the house, were free of toxins and irritants that might impact health. We also took steps to discourage biological pollutants such as dust mites and molds. We worked from the ground up, starting with the... FOUNDATIONMoisture-proofing the home's foundation was critical to prevent mold growth. The house was situated so that rain water would drain away from the foundation. We also installed a continuous, 6mm polyethylene vapor barrier on the ground and crawl space walls, as well as a perforated footing drain system connected to the storm drain.FRAMINGHealthy House features solid wood joists and I-beams instead of composite boards, which often contain urea-formaldehyde glue binders. We did use an oriented strand board, a type of composite plywood, for the home's sheathing, because it was completely sealed off from the home's interior by our air-barrier insulation system.DUCTWORKSheet metal ductwork throughout the home's interior was sealed at all joints with a non-toxic mastic to prevent dust and pollen from entering the ductwork and circulating throughout the house.Properly sealed ductwork also adds to energy efficiency and helps balance the air flow so that neutral pressure exists within the house (supply air flow equals exhaust air flow). Excess negative or positive air pressures in the house can cause problems. If negative pressure is created, appliances may backdraft, resulting in carbon monoxide poisoning. In areas where soil gasses such as radon are present, negative pressure could result in those gases leaking into the home through the foundation. If a positive pressure is created, moisture generated by normal activities within the house will be driven into the walls. There the moisture can cause mold growth in interior wall cavities and eventually lead to structural degradation. Additional cold air returns were installed in the bedrooms to provide better heat distribution and reduce pressure-induced problems. All floor registers were sealed during construction to prevent dirt and debris from entering the duct system. When construction is complete, all the ductwork will be cleaned to remove any particles. INSULATIONHealthy House features a state-of-the-art, air-barrier and insulation system called Icynene, which instantly expands to completely fill every cavity with a flexible foam. This water-based product contains no toxic compounds such as formaldehyde, chloroflurocarbons, or hydrochloroflurocarbons. Icynene is also resistant to bacteria and fungus.Because it acts as an air barrier, Icynene Insulation creates an air-tight envelope within the home. This minimizes the dust, pollen, and contaminants that can enter from outside and makes indoor air quality more manageable. Icynene helps Healthy House stay comfortable in both winter and summer by controlling air and moisture movement, which also means better energy efficiency. VENTILATIONAdequate ventilation is one of the most critical components to a home's indoor air quality. A whole-house mechanical ventilation system means that every room in Healthy House is supplied with fresh, filtered air on a regular basis, while the stale air is removed.Installed in the garage and ducted to the house and outside, the vanEE Energy Recovery Ventilator provides a fresh air exchange every three hours. It also helps reduce heating costs by recovering 80% of the heat energy from the stale air and transferring it to the incoming fresh air. Dust and pollen is filtered out by the vanEE, and the constant air exchange helps control excessive humidity within the home that can lead to mold and dust mites. WINDOWSOur energy-efficient windows are double-paned, low-E/argon windows. A microscopically thin "low-E" (low emissivity) metallic coating on a window's glass surface provides optimal energy-saving benefits by selectively filtering the sun's energy in the summer and reducing heat loss in the winter. A low-E coating also lets in visible sunlight while blocking the infrared and ultraviolet solar energy that drives up cooling costs and damages curtains, furniture, and carpets. Argon gas fills the space between the double panes to add extra insulation.FIREPLACEThough we all find a fire cozy and inviting, a fireplace can be a significant source of indoor pollution. Wood smoke can trigger asthma episodes as well as irritate healthy lungs. An improperly vented gas fireplace can cause combustion gases to leak into the home. For Healthy House, we chose a sealed-combustion gas fireplace placed on an exterior wall and vented directly to the outside.FURNACE AND WATER HEATERWe placed our gas furnace and gas water heater in a sealed but accessible mechanical room in the garage, outside the home's airtight envelope and vented to the outside. This eliminates any worry about combustion pollutants spilling into the home. Installing a sealed-combustion gas furnace and gas water heater is another alternative.Furnace filters should be changed quarterly and the furnace should be serviced annually to prevent dust and particulate matter from entering the heating system. A four-inch pleated filter is recommended for best control of small particles. CENTRAL VACUUMHealthy House features a central vacuum system with the collection canister located in the garage. Unlike conventional household vacuums, which often emit dust and particles back into the air, the central vacuum system efficiently removes dust and deposits it outside the home's breathing environment. Locating the collection canister in the garage means that dust and allergens remain outside the home even when the bag is changed and the tank is cleaned.FLOORINGWe chose exterior-grade plywood for the subflooring in Healthy House because it does not contain the urea-formaldehyde found in particleboard or interior-grade plywood, which are typically used. Exterior-grade plywood does a contain phenol-formaldehyde binder, but it is a low-emitting formaldehyde.Healthy House features mostly hardwood floors and tile throughout the home. Smooth-surface flooring such as wood, tile, vinyl, marble, or cork is easy to clean with water, which is important when it comes to battling dust mites. Use a non-toxic, water-based adhesive to install vinyl flooring. Our hardwood floors have a waterborne finish that won't off-gas irritating chemicals or toxins. A harder finish flooring (which may contain more VOCs) that has been sanded, stained, finished and allowed to off-gas in the factory before it is installed is another alternative. CARPETBecause it can harbor dust mites, mold, bacteria, and irritating particles, we used a minimum of wall-to-wall carpeting in Healthy House. Also, some carpeting contains a variety of synthetic chemicals added to improve certain characteristics, such as stain resistance. Other carpet treatments include fire retardants, fungicides, and pesticides, all of which can off-gas in the home and affect sensitive individuals.Because some people do want carpet, we chose a 100% nylon, low-nap carpet for Healthy House that is low-VOC and contains no urea-formaldehyde. Nylon carpet is a less hospitable environment for dust mites than some natural fibers. We used a low- VOC carpet pad, avoiding the rebond composite foam material that contains toxins. If wall-to-wall carpeting that is treated with chemicals is installed, ask the carpet dealer if it is possible to unroll the carpeting and allow it to off-gas in the warehouse for at least 48 hours prior to installation. When choosing area rugs, stick to washable, natural fibers with natural backing instead of latex, which can cause allergic reactions in some people. PAINTMost paints contain volatile organic compounds (VOCs), organic chemicals that readily evaporate into gases at room temperature even after the paint is dry. For Healthy House, we chose low-VOC primers and paints for both the interior and exterior of the house. Low-VOC paints emit virtually no odor during or after application.We also applied a vapor barrier primer to the interior wallboard first to prevent moisture generated by normal household activities from seeping into the walls, where it can cause mold growth and structural damage. If using paints or finishes that are not labeled low-VOC, be sure to ventilate the area well while painting and allow the products to dry and off-gas thoroughly before using the area. CABINETRYThe kitchen and bathroom cabinets in Healthy House are made with solid wood doors and non-toxic plywood boxes, not the commonly used particleboard that contains urea-formaldehyde. The plywood boxes are then sealed with a solid wood veneer. Hardwood cabinetry should be finished with a low-VOC sealer.TILECeramic tile is another smooth surface that is easy to clean and does not harbor dust. We used tile flooring in the kitchen, utility room, and bathrooms and sealed the grout to prevent mold growth.COUNTERTOPSWe used a formaldehyde-free underlayment for the countertops and a water-based mastic to apply laminates. Where tile is used, a sealer is applied to the grout to prevent mold growth.CAULKS, ADHESIVES, JOINT COMPOUNDSWe used non-toxic or low-VOC caulks, adhesives, and joint compounds throughout Healthy House.TRIM AND MOLDINGWood trim and molding made of composite materials or plastic may contain formaldehyde or other irritants. Choose solid wood instead and use a low-VOC primer, paint, or sealer.APPLIANCESProper ventilation of fuel-burning appliances is an important consideration in Healthy House because it is so tightly sealed. We chose an electric range for our kitchen, but sealed combustion gas stoves are available. A gas range should have a mechanical exhaust hood located directly above the cooking surface to exhaust combustion by- products and moisture directly to the outside. An improperly vented or inadequately sealed gas range can produce harmful combustion pollutants such as carbon monoxide and nitrogen dioxide.Our gas furnace and gas water heater are located in a separate mechanical room in the garage, outside the home's airtight envelope, to avoid exposure to any combustion pollutants in the home. FURNISHINGSIKEA Home Furnishings furnished Healthy House with sleek, attractive furniture that is easy to keep clean. We chose smooth, flat-weave upholstery fabrics, avoiding the deep-nap or fleecy fabrics that can harbor dust mites. People sensitive to synthetics that may contain formaldehyde or irritating dyes and chemical treatments will want to investigate IKEA's line of untreated, natural fiber upholstery fabric.Solid wood furniture is preferred to particleboard, which contains formaldehyde. Learn more about IKEA's efforts to minimize the use of formaldehyde in its products. Again, we looked for clean lines that won't catch a lot of dust and particles. Though we kept accessories to a minimum to provide fewer safe harbors for dust mites, Healthy House provides an attractive and welcoming indoor environment. WINDOW TREATMENTSEasy to keep clean and dust-free is the key to window treatments. If you choose blinds, the vertical style is easiest to keep dust-free: horizontal blinds can be wiped with a damp cloth or vacuumed with a special attachment.Select curtain fabrics that can be taken down and laundered regularly. Keep in mind that formaldehyde is used in the finishing of all permanent press material. LANDSCAPINGIn order to avoid the use of pesticides and to keep watering and fertilizing to a minimum, we chose native Northwest plants for the yard at Healthy House. Taking allergies and pollens into consideration when selecting landscaping plants is an obvious choice for some homeowners, but the plant you are most sensitive to may be only a yard away! That's why a ventilation system that filters dust and pollens from the outside air before it is introduced to the indoor breathing environment is important.
This document was published on 04/01/98. |
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