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|Using Less Wood in Buildings|
Building construction accounts for nearly one half of the wood consumed in the United States. Efficiency strategies can be implemented and "good" wood and non-wood alternatives can be used. Changes are needed throughout the design and construction process to ensure building sustainability.
by Ann V. Edminster
Nearly everyone in the building industry is concerned with deteriorating lumber quality, increasing prices, and devastation of old-growth forests. Building, especially residential construction, accounts for more than 50 percent of the wood consumed in the United States (U.S. Commerce Dept., 1993). Our per capita wood consumption is far greater than that of any other nation and is incompatible with sustaining forest biodiversity. Although the U.S. is home to only five percent of the global population, it is responsible for over fifteen percent of the world's consumption of wood (Environmental Defense Fund, 1994).
The overarching goal of the Wood Reduction Clearinghouse ( ed. note: the Wood Reduction Clearinhouse is now the Resource Conservation Alliance) is to lessen wood use by promoting five strategies: redesign, reuse, recycle, replace, and reduce. We will discuss the wood shortage debate, sustainable logging, more responsible uses of wood, alternative materials, and future challenges.
The U.S. timber products industry spends millions of dollars each year promoting the idea that building with wood is an environmentally sound choice. Their ads claim that there are more trees in America today than ever before. The subtle trap is that these statistics do not differentiate between young sapwood trees and high-quality heartwood, or between diverse natural forests and single-species tree farms.
In the U.S. today, less than five percent of our original forest cover remains, and the clearcutting of old-growth forests continues. Intact forests support indigenous peoples, shelter wildlife, maintain the quality of fisheries and watersheds, conserve soil, moderate the global climate, and store much of the planet's genetic material. They may be our most important natural resource.
The construction industry uses 46 percent of the softwoods harvested in the U.S., for framing lumber and plywood, most of which comes from the Pacific Northwest and British Columbia. The U.S. Forest Service predicts that harvests from the Pacific Northwest have peaked and will fall steadily over the next ten years (Adams, 1994). Present demand has exceeded our forests' ability to supply lumber, even with the industry's prevailing unsustainable practices. British Columbia, however, now has one of the highest logging rates in the world: an acre of old-growth forest is clearcut every 66 seconds (Rainforest Action Network, 1995). It is imperative that we reverse this trend.
Changing the way we use wood in construction can alter the course of forest destruction, allowing us to save some forests from being turned into tree farms and preserving forest ecosystems for future generations.
There are numerous strategies in building design for reducing demand for new wood. A baseline strategy in the spectrum of sustainable design options is the choice of not designing a new building at all. Reusing an existing structure ensures a net savings in consumption of new resources. Particularly in metropolitan areas, there are often scores of distressed buildings, many of historical or aesthetic value, crying out for renovation. The Audubon Headquarters Building in New York City is such an example. This historic building was saved from demolition and renovated according to an extensive set of resource conservation criteria and is often cited as a successful model for "green" renovation.
In terms of conceptual simplicity, second only to avoiding the construction of a new building is the approach of designing a smaller building, an option that is also often overlooked. This is an area of potentially great opportunity for design professionals. Good design is the surest route to a building that achieves more in less space and with less material waste. This is a persuasive point when lobbying clients to "do the right thing."
A third strategy is to get more use out of a single facility. Schools, community centers, theaters, civic centers, and other similar uses can often share space because they occupy facilities on different schedules but have similar requirements. There is also a potential synergy between this approach and the work-at-home or cottage industry movement.
Reuse and recycling are simply two stages of the same process of matter descending in the entropic scale, towards ever-greater disorganization. Part of our job in promoting the agenda of sustainable building practice is to insert more stages into this progression. Standard practice now is to take wood from its highest state, the forest, put it into a building, and then remove it immediately to its lowest state, the landfill or incinerator. This is an irresponsible use of a precious resource.
Reuse can represent one or more additional stages in the lifespan of a piece of wood, depending on a number of factors. Ideally, a building would be designed so that every piece of wood is fully recoverable upon removal from the building, and reusable in the same condition (size, shape, etc.). This would theoretically make it possible for the wood to be reused over and over again, indefinitely. In the indigenous building methods of certain nomadic peoples, poles that support the roof are the only wood features. These are so precious that the family takes them with them when they move. In our reality, this may be a somewhat more difficult objective to achieve; however, careful design of mechanical connection details is a crucial step toward that ultimate goal. If the fastening system is designed such that the framework of a building may be readily dismembered, rather than rent apart by brute force, the odds of a high percentage of the wood being suitable for reuse are much higher.
The Institute for Asian Studies at the University of British Columbia, designed by architect Eva Matsuzaki, is a prime example. The building scheme, originally conceived with a concrete frame, was revisited when a nearby armory on the university campus was slated for demolition. The armory had magnificent timber trusses, which were salvaged to supply 60 percent of the framework for the Asian Studies building. The new building was also thoughtfully designed with its own responsible deconstruction in mind. In addition, the wooden structure is exposed on the interior of the building, both cultivating appreciation for the beauty of the material and decreasing the need for finishing materials.
Wood is a highly desirable building material. Although we need to radically decrease our rate of consumption of new wood products, they will continue to have a place in the palette of material choices. However, the goal of forest stewardship demands that we drastically revise our current patterns of use.
There is a great deal of scope for using the wood we build with more responsibly. Several strategies exist for doing this, including choosing products that use wood in highly efficient ways and that use wood that is already at a lower material state (recycled wood products); and designing frameworks so as to optimize the wood within them, in terms of both technical performance and aesthetics. It is also important to design to protect wood from moisture and pests.
Cultivating a mindfulness that larger dimension solid-sawn lumber generally comes from older trees and richer, more complex forest ecosystems is a fundamental first step toward responsible wood use.
We would do well to conceive of solid lumber as, primarily, a valuable, beautiful material that deserves to be used in ways that highlight its intrinsic qualities. To paraphrase Ianto Evans, 'wood is too precious to be the main building material. Instead, it should be used as a condiment.' This may mean, among other things, striving to use high quality wood, such as large dimension structural members or straight grain fir, where they are seen and appreciated, as in exposed beams and beautifully detailed doors. When wood is hidden, we should specify products that employ wood fibers in the lowest feasible state, such as finger-jointed studs sandwiched between stucco and gypsum board, or finger-jointed trim covered with paint.
Eliminating design complexity, particularly where meaningless in functional or spiritual terms, is another important strategy. Fussy, trendy, anachronistic rooflines, cupolas, and turrets such as array the streetscapes of contemporary subdivisions are palliative attempts at endowing these spiritless developments with aesthetic substance. They succeed only in driving up cost, gratifying consumerist impulses, and devouring lengths of framing lumber, spitting them out into short pieces that, within the current dominant paradigm, have no productive future. The best we can do with them now is to grind them up for garden mulch. Thus, as designers, we have responsibility at both ends of the building lifecycle-- during conception, incorporating reuse as a conscious goal; and during demolition, specifying wood recovery to the greatest extent feasible.
There are a number of approaches to optimizing the wood used in building frameworks. One of these is heavy timber framing, which uses less lumber overall than stick framing, uses it visibly and reverently, and in highly durable construction. When the probable lifespan of a building is measured in centuries, as is typical for a heavy timber frame building, rather than in a meager number of decades, the material and environmental costs of the building are shared by several generations. This may provide a justification for using higher quality lumber.
In other cases, such as the Davis Energy Group's ACT2 Energy House, careful design and construcion of otherwise conventional stick framing has resulted in considerable savings in wood-in this case, 25 percent.
Selecting Efficient Products
Wood can be used in more or less efficient configurations. As architects, we have the potential to exercise substantial influence on demand patterns-for instance, we can make an active decision to use wood trusses rather than larger-dimension rafters. Carrying this logic one step farther, we have the option of specifying products like I-joists and micro-lams instead of dimensional ceiling and floor joists, mini-lams instead of girders, glu-lams and parallel strand lumber instead of solid wood beams. Simply substituting oriented strand board for plywood feeds the demand for a product that is often made of much smaller and lower value wood pieces, such as mill waste, marginal or diseased trees, and urban tree waste.
The ReCRAFT 90 House in Missoula, Montana, by Steve Loken, which was recently featured on the cover of Parade magazine in newspapers across the country, incorporates many of these types of products.
There are unanswered questions about this class of materials, called engineered wood products. Among them are toxicity, both within the production processes and outgassing from the final materials. Another issue is whether they do, in fact, utilize the types of waste wood that they purport to use; there is not now a credible way of factually ascertaining this.
Depending on your location, your lumber may come from more or less poorly managed forests. Investigating how each brand and variety of lumber on the market was harvested would require extensive, time-consuming research. But since most lumber is produced unsustainably, the likelihood is that the wood you buy comes from a decimated forest. The most powerful tool for changing logging practices is to demand a better product.
Specifying and purchasing certified sustainably harvested wood is the only way to be sure that the new lumber you are using for a project has been harvested without endangering forest and planetary ecosystems. In brief, certification means that a company's harvesting procedures have been audited and deemed ecologically sound. This certification may come in a variety of forms but should include all of the following factors: involvement of indigenous and local peoples, long-term forest health, minimal environmental impact, and maintenance of biodiversity and primary forests.
In order for the certification to be credible, it must be performed by an independent third party. If not, there is no guarantee that the approval is not just industry "green washing." The Forest Stewardship Council (FSC), an international nonprofit organization, is the premier organization for accrediting groups that certify timber operations. All FSC members must abide by global and comprehensive standards and are audited annually. Currently, making sure that the wood you purchase is certified by an FSC-accredited organization is the only guarantee that it was harvested in an ecologically sustainable manner.
Reducing demand on wood can also be achieved by using materials other than wood. We are now in the midst of an alternative building boom. There has been a resurgence in rammed earth, straw bale, and cob construction, among other systems, largely thanks to the persistence of some visionary individuals, such as David Easton, Matts Myhrman and Judy Knox, and central Oregon's own Ianto Evans of Cob Cottage Company. Their efforts of many years are just now coming to fruition as the exponential impacts of patient, dedicated education-not isolated, back-woods endeavors-are becoming visible to a wider public. And now, as practitioners of these various methods increasingly come together to share ideas in forums such as this Eco-Design Arts Conference, we are starting to see some real momentum toward more sustainable building systems. It is important to remember that the best solutions arise from creative struggle and collaboration, not from rigid, zealous adherence to singular solutions.
A case study of a mix of techniques and materials is the Ecological Design Institute's design for the Real Goods Sustainable Living Center in Hopland, California, now approaching completion. The roof members are made of local sustainably harvested lumber. The design team had considered site-building glued-laminated beams but ultimately rejected that option because it would have entailed milling beautiful old, vertical-grain fir into small pieces, then laminating the larger faces of the pieces to one another where their beauty would not be seen-in other words, they would have unnecessarily degraded the wood. In addition, the building utilizes a hybrid straw bale and soil-cement shell wall, rather than a wood-framed wall system.
Straw bales and earthen building methods, along with more conventional materials like steel and concrete, all have the potential to lessen wood demand, particularly with the continued creative efforts of innovative designers and builders such as those present at this conference.
It is worth emphasizing that the impacts of choices about materials used in a building vary from place to place, and these choices, like other design decisions, should be made in a context of bioregional appropriateness. Using less wood in buildings often means using more of some other material or materials. These are choices not without cost implications, environmental as well as monetary. Many negative environmental impacts arise from building activity, ranging from sound pollution and damaging air and water emissions, to environmental illness and global warming. How is it possible to evaluate the relative environmental benefits and liabilities of different building materials?
Although there are few, if any, hard and fast answers to this question, one of the keys is to think in terms of systems. A recent exchange on the Internet illustrates this point. A self-affirmed "green" architect posted a message citing the embodied energies of steel, concrete, and wood, in terms of megaJoules per kilogram of material. Pointing to the value given for concrete as the lowest of the three, he hypothesized that concrete was therefore the most environmentally benign of these materials.
This incident spotlights the pitfalls of environmental impact assessment. Embodied energy is not the sole nor even, necessarily, the most important index of environmental evil or virtue. It happens to be both a significant one-as energy is closely correlated to carbon dioxide emissions, which, in turn, are a principal contributor to global warming-and a quantifiable one. Many environmental impacts are not readily measurable, and it is therefore difficult to get a firm grasp of their import. To arrive at a sound environmental evaluation, however, it is necessary to look at the whole spectrum, or system, of impacts, not just a single index such as embodied energy.
The second failure to take a systems perspective, in this instance, is even more glaring: namely, that one doesn't simply substitute a kilogram of concrete or a kilogram of steel for a kilogram of wood in a building application. When we choose to design with a given material, that material resides within a whole building system, the features of which are project-specific, from the fastening method to the cladding to the configuration of the building's structural armature. It would be a rare situation, indeed, where a choice of materials, particularly structural materials, had no effect on other design decisions.
There are a number of methods of assessing the environmental impacts of building systems. Without getting into the details of those methods, they can be summarized by noting that they represent a spectrum in terms of the impacts evaluated, the importance given to those impacts, and the degree of objectivity or subjectivity entailed in the assessment. Among the quantifiable impacts are embodied energy, air and water emissions, waste byproducts, and indices of toxicity. No less important, but not easily measured, are impacts such as forest ecosystem destruction. From a planetary perspective, this is one of the most urgent. However, we have no universally accessible, convenient, definitive instrument for measuring this impact.
Rethinking the Design Process
We need to begin to make a number of changes in our own processes before we will achieve effectiveness as change agents. We can't come up with a better "product" using the same old flawed methods. Initially, responsible designers will look to their bioregion to supply as much of their building resources, both human and material, as possible, as well as to discern the indicators of the pressing environmental resource issues of their place. If we begin to live responsibly within our own places, we will ultimately learn to be more effective in making wider-reaching design decisions.
The reach of our actions is almost incomprehensible. Among other things, accepting this reality means beginning to think in terms of longer life spans for our buildings. A building's longevity hinges on two primary factors: durability and adaptability. The design and construction must be fundamentally sound in order to continue to serve people for successive generations. Equally important is that our buildings be designed to respond to change. Households shrink and grow, patterns of living change, and building uses often change over time. If we design our building systems and spaces to accommodate these changes, we improve the odds that our architecture will withstand the tests of time.
It is also imperative that we cease to think of "green" design as carrying a premium price tag-as representing either a ten percent cost increase or an equivalent sacrifice of floor space. Instead, designing with sustainable, healthy materials and systems needs to be established as a fundamental value, right alongside utility, comfort, and beauty; to become simply another influence in the budget allocation process, not a cost item unto itself. While we can't control our clients' value systems, we can make a concerted attempt to educate them about the consequences of their choices. How many of our clients donate to environmental organizations, but have no awareness of the environmental import of their decisions about their homes? There is an opportunity to redirect people's existing desires to do the right thing, through education.
The paths to sustainable building practices are largely uncharted, and they are undoubtedly as numerous as there are innovators and trailblazers among us. Among the few certainties is that challenges aplenty lie ahead. Several tasks have already been identified.
Adams, Cassandra, "The Impacts of Architects & Builders on Forest Sustainability,"Earthword, Laguna Beach, 1994.
Environmental Defense Fund, Draft Report, Washington, DC, 1994.
Rainforest Action Network, Briefing Paper for Clayoquot Rainforest Campaign, San Francisco, 1995.
U.S. Department of Commerce, Statistical Abstract, Washington, DC, 1993.
This paper was written for the Wood Reduction Clearinghouse, which has now become the Resource Conservation Alliance. The author, Ann Edminster, received a Master of Architecture from U.C. Berkeley, specializing in environmental issues in architecture. She now works with the Natural Resources Defense Council writing about alternatives to conventional wood construction and strengthening alternative building initiatives throughout the country. Former Clearinghouse director Dana Harmon and associate Darren Korn also contributed to this paper.