Green Building News September 2004
September 29, 2004
Houses constructed with wood framing consume less total energy during their “lifetimes” than similar homes made with steel or concrete, according to a preliminary task force report by researchers from a dozen U.S. universities and U.S. and Canadian research organizations. The researchers analyzed the total energy used to manufacture and transport building materials, build a house, maintain it for a 75-year life-cycle, then demolish or dispose of it.
The analysis, called a life-cycle assessment (LCA), used sophisticated computer software to study four typical houses: a wood-frame and an identical steel-frame house in Minneapolis, and a wood-frame and an identical concrete-frame house in Atlanta. The Minneapolis houses were based on a 2,100-square-feet design with a basement. Both Atlanta houses used a 2,200-square-feet design on a concrete slab. All the houses complied with local building codes.
The researchers also calculated emissions of carbon dioxide, methane and nitrous oxide generated during the life cycles of the houses to determine the potential of different construction materials to impact climate change. Carbon emissions associated with energy use represented one of the more important environmental impacts, the report says.
In the first phase of the ongoing study, the researchers determined that construction of a typical Minneapolis steel-frame house would use 17 percent more energy than building an identical wood-frame home. The study's typical Atlanta concrete-frame house used 16 percent more energy than a matching wood-frame house.
The researchers also estimated the global-warming potential of the steel-frame home to be 26 percent greater than that of the wood-frame home; greenhouse emissions of the concrete-frame home were 31 percent greater than those of the comparable wood-frame home.
Several materials other than wood are common to all the houses, such as glass for windows, gypsum for wall board and sheathing, asphalt roofing and concrete for foundations. Concrete products, for example, account for more than 70 percent of the mass of the hypothetical wood-frame and steel-frame houses. Glass, gypsum, asphalt, steel and concrete are energy-intensive and make up the largest percentage of the energy required for home construction.
Much of the energy needed to produce wood building materials, on the other hand, comes from by-products such as bark, sawdust and trim, thereby reducing the consumption of fossil fuels.
Energy that would be used for heating and cooling during the useful life of the houses was calculated separately.
The study is being conducted by the Consortium for Research on Renewable Industrial Materials, which was formed in 1996 by a number of U.S. universities and several research institutes to update and expand a 1976 study by the National Academy of Science of the energy implications of using renewable building materials. Information from the current study is slated to become part of the Lifecycle Inventory Database Project database for use by architects, engineers and the general public.
The current study was partially funded by the USDA Forest Service Forest Products Laboratory (FPL), which focuses on housing and other wood-utilization research and is home to the Advanced Housing Research Center. Other funders included the U.S. Department of Energy, consortium members and private industry.
Using the least energy-intensive building materials – and recycling and reusing building materials – makes sense in light of the nation's concerns about energy, pollution and climate change, according to consortium president Bruce Lippke, who is professor of forest resources at the University of Washington.
Building 1.7 million houses of wood, steel and concrete consumes roughly 850 million gigajoules of energy annually—comparable to the energy used to heat and cool more than 10 million homes, Lippke said.
"Everything kind of flows from energy consumption," Lippke said. "If you're using energy, you're polluting water, polluting air and kicking out carbon dioxide emissions."
With better material selection and house-construction design the energy use could be reduced substantially. The report suggests other opportunities that could substantially reduce the energy demands of home construction including:
- Redesign houses to use fewer fossil-fuel intensive products
- Change building codes that result in excessive use of wood, steel and concrete
- Recycle demolition wastes
- Increase durability of homes through improved products, construction designs and maintenance practices.
A 12-page summary of the report, published earlier this year in the Forest Products Journal, is available through the consortium’s Web site.
National Solar Tour Puts Buildings on Display
More than 1,800 homes, business and public buildings will be on display during the annual National Solar Tour taking place Saturday, October 2nd. Many forms of renewable energy will be featured, including passive solar design, wind energy, solar hot water and photovoltaics. Last year, the tour attracted about 35,000 tour-takers in nearly 800 communities in 45 states last year.
“The value of these ‘state-of-the-shelf’ buildings is how well they demonstrate the ease with which innovative building technology has gone from the lab into standard practice in so many places in the country” said Brad Collins, Executive Director of the American Solar Energy Society. “This is not tomorrow’s hope; these are actual buildings, housing real people in real communities today. Not pioneer innovators, but folks like you and me who want to see what they can do to lower their personal dependence on foreign sources of energy or cut demand for polluting sources of energy. These building owners have a significant story to tell their neighbors – it’s not as hard as you think and there is great joy in watching the electric meter run backwards!”
Organized locally and promoted nationally, the National Solar Tour is a unique opportunity to learn first hand what works in peoples own home town. The tours are organized by chapters of the American Solar Energy Society, state energy offices and other volunteer groups who want to educate the public to be better energy consumers.
Local tours and contact information are available on the ASES website.
Mold Linked to Asthma, But Nothing Else
A new study conducted by Institute of Medicine of the National Academies confirms a link between mold and asthma. It also links mold and other factors related to damp conditions in homes and buildings with coughing, wheezing and upper respiratory tract symptoms in otherwise healthy people. However, no available evidence was found connecting mold and damp conditions with the wide range of other health complaints that have been ascribed to them. Given the frequent occurrence of moisture problems in buildings and their links to respiratory problems, excessive indoor dampness should be addressed through a broad range of public health initiatives and changes in how buildings are designed, constructed, and maintained, said the committee that wrote the report.
"An exhaustive review of the scientific literature made it clear to us that it can be very hard to tease apart the health effects of exposure to mold from all the other factors that may be influencing health in the typical indoor environment," said committee chair Noreen Clark, dean, School of Public Health, University of Michigan, Ann Arbor. "That said, we were able to find sufficient evidence that certain respiratory problems, including symptoms in asthmatics who are sensitive to mold, are associated with exposure to mold and damp conditions. Even though the available evidence does not link mold or other factors associated with building moisture to all the serious health problems that some attribute to them, excessive indoor dampness is a widespread problem that warrants action at the local, state, and national levels."
Excessive dampness influences whether mold as well as bacteria, dust mites, and other such agents are present and thrive indoors. Moreover, wetness may cause chemicals and particles to be released from building materials. Many studies of health effects possibly related to indoor dampness do not distinguish the specific health effects of different biological or chemical agents.
Through its careful review of the available scientific studies, the committee found sufficient evidence to conclude that mold and damp conditions are associated with asthma symptoms in asthmatics who are sensitive to mold, and to coughing, wheezing, and upper respiratory tract symptoms in otherwise healthy people. However, the evidence did not meet the strict scientific standards needed to establish a clear, causal relationship. An uncommon ailment known as hypersensitivity pneumonitis also is associated with indoor mold exposure in genetically susceptible people. Damp conditions and all they entail may be associated with the onset of asthma, as well as shortness of breath and lower respiratory illness in otherwise healthy children, although the evidence is less certain in these circumstances. Likewise, the presence of visible mold indoors may be linked to lower respiratory tract illness in children, but the evidence is not as strong in this case.
The committee found very few studies that have examined whether mold or other factors associated with indoor dampness are linked to fatigue, neuropsychiatric disorders, or other health problems that some people have attributed to fungal infestations of buildings. The little evidence that is available does not support an association, but because of the dearth of well-conducted studies and reliable data, the committee could not rule out the possibility.
Studies on animals and cell cultures in labs have found toxic effects from various microbial agents, raising concerns about whether these same agents growing in buildings can cause illness in people. Molds that are capable of producing toxins do grow indoors, and toxic and inflammatory effects also can be caused by bacteria that flourish in damp conditions, the report noted. Little information exists on the toxic potential of chemicals or particles that may be released when building materials, furniture, and other items degrade because of wetness. The committee recommended that current animal studies of short-term, high-level inhalation exposures to microbial toxins be supplemented with new research that evaluates the effects of long-term exposures at lower concentrations.
Moisture and mold problems stem from building designs, construction and maintenance practices, and building materials in which wetness lingers. Technical information describing how to control dampness already exists, but architects, engineers, building contractors, facility managers, and maintenance staff do not always apply this knowledge, the report says. Training curricula on why dampness problems occur and how to prevent them should be produced and disseminated. Guidelines for preventing indoor dampness also should be developed at the national level to promote widespread adoption and to avoid the potential for conflicting advice from different quarters. In addition, building codes and regulations should be reviewed and modified as necessary to reduce moisture problems.
Research on various means to prevent or eliminate excessive dampness -- including educational initiatives and building renovations or design changes -- should be undertaken to find out which are effective. While there is universal agreement that promptly fixing leaks and cleaning up spills or standing water substantially reduces the potential for mold growth, there is little evidence that shows which forms of moisture control or prevention work best at reducing health problems associated with dampness, the report notes. In addition, materials designed to educate the public about the actual health risks associated with indoor dampness should be developed and evaluated. The effectiveness of economic and other incentives to spur adherence to moisture prevention practices -- such as bonuses for facility managers who meet defined goals for preventing or reducing problems, or fines for failure to correct problems by a specified deadline -- should be evaluated, and successful strategies should be implemented.
The committee had insufficient information to recommend either an appropriate level of dampness reduction, or a safe level of exposure to organisms and chemicals linked to dampness. Better standardized methods for assessing human exposure to these agents are greatly needed, the report says. It calls for studies that compare various ways to limit moisture or eliminate mold and to evaluate whether the interventions improve occupants' health.
Report Cites Flaws in LEED System
A new report by Platts, the energy information division of The McGraw-Hill Companies, identifies flaws with the Leadership in Energy and Environmental Design (LEED™) rating system that it says threaten the long-term viability of the program.
“LEED has successfully created a framework that enables a wide variety of construction industry players to offer green building features as standardized options,” said Jay Stein, a managing director of technology research at Platts and coauthor of the report. “But that success has not come without cost.”
Taryn Holowaka of the U.S. Green Building Council said that they had not seen the report and had no response.
According to Stein, the LEED system is simple enough to allow mainstream industry players to participate in green building projects, but much of the critical information that designers and clients need to make informed choices is lost. The report, titled “Ensuring the Sustainability of Sustainable Design,” cites two key problems: Buildings that earn more LEED credits do not necessarily provide more environmental benefits than buildings that earn fewer credits, and some of the techniques LEED encourages are not consistently a superior means of reducing environmental impacts.
Stein notes that the USGBC is concerned about these issues, which threaten the credibility of the LEED rating system, but the process to fix them could take several years. “Designers need techniques they can use now to help ensure the sustainability of the LEED rating system.”
Platts, once known as E Source, was established as a for-profit subsidiary of the Rocky Mountain Institute. The company became independent and was later purchased by McGraw-Hill.
New Report Shows Saving Water Cuts Energy Use
A new report shows the hidden connection between two scarce resources, energy and water. The report's authors say that saving water is an untapped way to also save energy and even to keep the lights on when the electric grid is strained during hot summer months.
"Few people realize how much energy we use when we turn on the tap," said Ronnie Cohen, a policy analyst with Natural Resources Defense Council (NRDC) and co-author of the study, "Energy Down the Drain." "Conserving water and improving efficiency, doesn't just save water, it also saves energy, cuts electricity bills, and reduces pollution from power plants."
California's State Water Project (SWP), which transports water from Northern California to Southern California is the state's largest single energy user, consuming 2 to 3 percent of all electricity. It takes tremendous amounts of energy to pump the water 2,000 feet over the Tehachapi Mountains -- the highest water lift of any water system in the world.
But water pumps aren't the only energy consumer. Every step along the way, from source and conveyance to wastewater treatment, requires energy. Yet the report says policymakers rarely consider the energy costs -- and potential savings -- in water supply planning.
"With power shortages and water scarcity a constant threat across the West, it's time to look at water and energy in a new way," said Dr. Gary Wolff a co-author of the report and principal economist and engineer with the Pacific Institute. "But too often, policy makers and water and energy experts ignore the links. The good news is we can reduce our energy use, cut air pollution and create new energy supplies with cost-effective improvements to water efficiency."
People in San Diego -- and throughout California -- could lower their energy bills by conserving and using water more efficiently. "It takes a lot of energy to heat the water for dish washers, clothes washers and showers," said Cohen. "People who have more efficient appliances are going to save on both their water and energy bills."
Learn to Design High Performance Schools
The High Performance School Design Online Training aims to help architects and engineers design more sustainable, cost-effective, and energy-efficient K-12 school buildings.
The 25-course curriculum covers the following areas: Introduction of High Performance Schools and the Online Curriculum; Design Criteria (CHPS and LEED®); Site Design; Lighting and Electrical Systems; Daylighting and Windows; Energy Efficient Building Shell; Mechanical and Ventilation Systems; Renewable Energy; Water Conservation; Recycling Systems, Waste Management and Construction Management; Transportation; Resource-Efficient Building Products; Health and Productivity; and Commissioning. Three courses on high-performance school operations and maintenance related to building envelope, lighting systems, and HVAC/mechanical equipment are scheduled to be added to the Web site in October 2004.
The courses were developed on behalf of NYSERDA by the Sustainable Buildings Industry Council (SBIC), Building Media, Inc., the New Jersey Institute of Technology, the Architectural Energy Corporation, and the Collaborative for High Performance Schools. The program is based on the U.S. DOE Rebuild America program’s National Best Practices Manual for Building High Performance Schools.
The program offers 25 Learning Units in Health, Safety and Welfare under the American Institute of Architects’ Continuing Education System (1 Learning Unit for each course successfully completed). The online courses have been underwritten through state and federal support and are currently offered free of charge. The program has more than 500 registered users in 40 states.
The training was developed by the New York State Energy Research and Development Authority (NYSERDA), with support from the U.S. Department of Energy (DOE) and the National Association of State Energy Officials, presents.
Construction Waste Resource Available
The U.S. General Services Administration (GSA) has recently updated its online Construction Waste Management Database to assist the building industry in reducing construction and demolition waste. Recyclers of construction and demolition waste may advertise their services free on this site.
The U.S. EPA estimates that each year 136 million tons of construction and demolition waste are generated in the United States. GSA’s Construction Waste Management program promotes the responsible disposal of this waste, including concrete, asphalt, masonry, wood, and other materials, much of which can be recycled or processed for reuse if handled properly.
Created in 2002 by GSA's Environmental Strategies and Safety Division, the Construction Waste Management Database is a free online service for those seeking information on companies that haul, collect and process debris from construction projects. To assist end-users, the database has also been improved to allow searches by state and zip code and by over 15 commonly-recycled construction waste materials.
Journal of Green Building Announces First Call for Papers
An international, peer-reviewed journal focusing on sustainable construction will begin publication in Spring 2005. The Journal of Green Building invites submission of technical papers for its inaugural edition. The aim of the publication is to provide a high-quality, interdisciplinary forum for advancing the state of knowledge about green building and high performance, sustainable facility and infrastructure systems. Submissions are welcome from authors in the fields of engineering, architecture, design, construction, facilities management, and all disciplines relevant to the life cycle of built facilities and infrastructure.
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