This article was originally published in the November/December 1993 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.



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Home Energy Magazine Online November/December 1993



Conservation Clips is compiled by Cathlene Casebolt of the National Center for Appropriate Technology, a non-profit organization working in sustainable energy, agriculture, affordable housing, and environmental protection. Conservation Clips contains brief summaries of useful research reports and articles in related magazines, and other publications collected by the NCAT staff. Contact NCAT, P.O. Box 4000, Butte, MT 59702. Tel: (800) 428-2525; Fax: (406)494-2905.



Air Handlers and Carpet Discoloration. When homeowners in a new subdivision in Pleasanton, California noticed carpet discoloration along the baseboards of their homes, Building Science Corporation (BSC) set out to find out why. The detached, two-story, single-family homes were wood-framed, with stucco and hardboard siding, built over concrete slab-on-grade foundations or crawlspaces. Each home was served by two gas furnaces/air-conditioners, one for each floor, which were located in the garage, with atmospherically vented chimneys and draft hoods. Supply ductwork for the first-floor air handlers was placed in the crawlspace or in the concrete slab; second-floor ductwork was placed in the vented attics. Both air handlers have a single return duct located in each floor's hallway. During its investigation, BSC found gaps in the supply ductwork, which cause negative pressure within the house. Air pressure testing indicated neutral pressure (+/-1 Pascal) when neither air handler was operating, but the houses became depressurized (4 to 8 Pascals negative pressure) when both air handlers were operating. When its door was closed the master bedroom became slightly positively pressured (less than 1 Pascal positive pressure), but the home's main living area became further depressurized. BSC's Joe Lstiburek concluded that when the air handlers depressurized the house, dust and other matter was drawn into the house from outside at the baseboard openings. The carpet served as a filter for this matter, resulting in the discoloration. Lstiburek noted that the stucco homes and those homes with slab-on-grade foundations showed less discoloration, because they had fewer leakage openings. To remedy the problem, he recommended identifying and sealing duct leaks; installing return duct in master bedroom; installing transfer grilles between other rooms and hallway; and installing fresh air supply duct from exterior to return side of primary air handler. EEBA Excellence, Volume VIII, 1993, Energy Efficient Building Assoc. Inc., Northcentral Technical College, 1000 Campus Drive, Wausau, WI 54401. Tel: (715)675-6331; Fax: (715)675-9776.

The Inefficiency of Ventilation Systems. While mechanical ventilation equipment is sometimes necessary to maintain indoor air quality, today's systems have absolute efficiencies of only 1%-10%, and often last only several years due to poor quality, according to Jim White, in his article Why Ventilation Equipment is SO Inefficient. The inefficiency is caused by the fact that when several devices operate in series to perform a task, the inefficiencies of each step will feed on the others in the chain. Losses feed on losses until the results are ludicrous. While some well-designed and well-built fans can be 50%-85% efficient, the worst ones available may be only 30% efficient, and then actually operate at about 10% efficiency because of a poor match between the fan performance and the load. Because systems are often oversized, they operate at less than peak efficiency; this can only be solved with designs that reduce input as the output is reduced (currently available systems typically have a steady input). Even some of today's better motors still use 300% more energy than they deliver; however, an improved design would allow efficiencies of as much as 90%, consuming about 111%-125% of the energy they deliver. White says the best way to reduce energy consumption of inefficient equipment is to switch from 1% air exchange efficiency to 10%, and from 5% to 20% for forced-air systems. When selecting a new unit, be sure that the motor and fan are properly matched to the load, and ask the supplier to provide information on power input versus flow and pressure, and use the information to calculate its energy efficiency. Indoor Air Review, February '93, IAQ Publications, Inc., 4520 East-West Highway, Suite 610, Bethesda, MD 20814. Tel: (301)913-0115; Fax: (301)913-0119.

Showerheads Wash Out. While low-flow showerheads have vastly improved in recent years, a recent study conducted by Pacific Northwest Laboratories shows disappointing results. PNL found that the water and energy savings from low-flow showerheads are 70% less than anticipated because conventional showerheads do not actually deliver as much water as analysts commonly assume. Some analysts assume that conventional showerheads use 5 gallons per minute as a baseline from which to determine savings, but in a study of 98 homes PNL found that conventional showerheads average only 3.2 gallons per minute, fully 36% lower than expected. The Energy Newsbrief, Volume 7 #41, May 31, '93. IRT Environment, PO Box 10990, Aspen CO 81612-9689. Tel: (303)927-3155; Fax: (303)927-9428.

Self-Healing Concrete. A new type of concrete that can repair its own cracks is being developed at the University of Illinois by Dr. Carolyn Dry. The product uses a cement which, under stress, develops a large number of very small cracks, rather than several large cracks, as do conventional products. In turn, the tiny cracks cause imbedded fibers to release an adhesive compound, which fills in the cracks. Because the cracks are self-healing, the process prevents water from settling in them, which can cause further damage. The product is still in the experimental stages. Journal of Light Construction, April 1993., Builderburg Partners, Ltd., 1025 Vermont Ave. NW, Washington, DC 20005. Tel: (802)434-4747; Fax: (802)434-4467.

Weatherization and Education. Even though hardware and weatherization measures improve the energy efficiency of a home, consumer behavior is still an important factor governing home energy consumption. Recognizing this fact, more and more low-income weatherization programs include an education component. About 4% to 20% more energy is saved when consumers are educated in the efficient operation of their home and its systems, compared to weatherization alone. A 1992 study of three Oregon counties revealed that energy education saved about 2,200 kWh per household annually, and that it had a long-term impact (at least two years) on energy consumption. Blue Mountain Action Council in southeastern Washington documented that its education component has increased energy savings by 8%. There are other benefits as well. For example, Pacific Power & Light found that consumers participating in its low-income weatherization program have improved their bill-paying habits after education. One drawback, though, is that consumers aren't always open to behavior modification, and may simply disregard it. Conservation Monitor, April/May '93, News Data Corp., Box 900928 Queen Anne Station, Seattle, WA 98109. Tel: (206)285-4848; Fax: (206)281-8035.

Microwave Clothes Dryer. Microwave dryers could be commercially available in about three years. An Oregon-based company, American Micro-Tech, has developed a prototype, which Southern California Edison has determined consumes 10% and 28% less energy than electric and natural gas units, respectively. In addition, the new unit can dry a load of laundry about 35% faster than conventional units. The Electric Power Research Institute is also testing customer satisfaction with the dryer's performance; researchers continue to work through potential technical problems. Additional tests are being conducted by two major manufacturers. Energy and Housing Report, March 1993, 9124 Bradford Road, Silver Spring, MD 20901. Tel: (301)565-2532; Fax: (301)565-3298.


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