Why Wood? Why Wood?
Why Wood? Sustainable Natural
Workable Plentiful
Renewable
Wood, the world’s greatest renewable resource®
Wood, nature’s sustainable building block, is a renewable resource that has excellent workability in all aspects of construction. Wood functions in harmony with its surroundings, blending seamlessly, yet making a bold statement.
And, instead of harming the Earth by depleting resources like oil and forcing carbon dioxide back into the atmosphere, wood grows plentifully and sequesters or captures carbon throughout its existence.
Wood products have been used for centuries to build businesses and homes, churches and schools, walkways and wagons. Today the use of wood is as relevant as ever. It is not only used to construct buildings but also to carry power and communication throughout the country; to create a safe harbor for both pleasure and work boats; to enhance homeowners’ lives with outdoor living spaces; and so much more.
But does the manufacture of wood products deplete this precious natural resource? What innovations help to extend the life of wood?
Harvesting
Forest land is more abundant today than it has been in the past 30 years. According to the USDA Facts and Trends from 2012, a third of the United States is covered in forests and of those, nearly 60 percent are privately owned, managed forest lands. It is from these managed lands that trees are cut for use in the building industry.
According to data from the USDA*
• there are 766 million acres of forest land in the U.S. today, about the same as 1907.
• overall, forest land in the northern U.S. has increased by almost 30 percent.
“We are creating a harmonized chain of production from tree to pole or pile or lumber.”
— Morgan Wright, Former Owner Wood Preservers, Inc.
Harvestable southern pine trees are planted at the rate of about 400 per acre. A forest thinning process at about 18-20 years helps remove underbrush, hardwoods and smaller pines. All of that material is used –either as compost, mulch for paper mills, furniture, or another wood use. At maturity (30+ years), the trees are harvested, once again using all material removed, and the land is readied for replanting.
As long as trees continue to be planted on managed lands and nurtured during the growth cycle, wood will be a plentiful resource.
Extending the Life of Wood
The forest products industry owns about 15% of all forest land; yet is responsible for 41% of forest replanting —
That’s about 3 million trees every day!
The treating industry has an important role in perpetuating the growth cycle of trees, continually researching ways to increase the longevity of wood while maintaining its natural beauty. Because preserved wood lasts longer, the need for the constant replacement necessary for untreated wood is eliminated; thus allowing for a longer growth period for managed forests. As long as wood is a desirable building material, managed forests will be maintained and harvested and new crops replanted. Therefore, extending the life of wood through preservation helps not only maintain forest land, but allows the growth cycle to continue..
Carbon Benefit of Using Wood
Trees are a natural resource that grow quickly and are completely renewable. Forest land is an asset to the environment because growing trees absorb carbon dioxide, which embodies the tree as carbon in the form of bark and wood. Using wood as a building material continues to be an environmental asset because the wood after being harvested, used as a building material, and even after treatment, continues to store carbon, which reduces wood’s carbon footprint. Older trees do not absorb carbon at the same rate as younger, fast growing trees used by the building industry. These trees, cut at their growth peak, also maintain a level of carbon whereas trees that burn or decay release carbon into the air in the form carbon dioxide. This causes elevated greenhouse gases.
WOOD IS EASY TO USE. It is a familiar building material easily handled by contractors and do-it-yourselfers. An affordable, available labor force can quickly install a project such as a deck. Wood is light weight, can be modified on the job site to adapt to project changes, and can be installed year-round in almost any climate. Wood’s design flexibility allows it to be used for a wide range of construction from buildings to backyard projects. It can be used as a finishing material simply adding natural beauty or as a structural material giving a cost effective way to meet building code safety as well as other requirements. Wood offers exceptional performance. Wood is made up of long chains of fibers that make it exceptionally strong, resisting stress while allowing the weight of the load to be shared over the length of the board. It is resistant to breaks and chipping and scratches can be easily repaired. Wood offers good acoustical properties. It absorbs sound and is not as noisy as steel or concrete structures can be. Acoustical problems arise when sound transmits through a structure that does not have adequate sound insulation or when reverberation occurs via hard reflective surfaces.
Treated Wood vs. Composites
Along with its flexibility, strength characteristics and workability, wood is a building material that is easy to use for contractors and do-it-yourselfers alike. There is no special equipment required to build with wood. Projects can be quickly completed with simple tools such as a hammer or drill and nails or screws. And, unlike composites, if lumber gets scratched or dinged it can be easily repaired by sanding and staining.
There are numerous life cycle assessments and studies on the environmental impacts associated with the national production, use, and disposal of treated lumber decking, especially when compared with non-lumber alternatives.
Life Cycle Assessment
According to a Life Cycle Assessment prepared by AquAeTer, Inc., the results for treated wood decking are significant:
• Less Energy & Resource Use: Copper azole-preserved decking requires less total energy, less fossil fuel, and less water to manufacture than wood plastic composite decking.
• Lower Environmental Impacts: Copper azole-preserved decking has lower environmental impacts in comparison to wood plastic composite decking in five critical impact indicator categories: greenhouse gas pollution, acid rain, smog potential, ecotoxicity, and eutrophicationcausing emissions.
• Less Fossil Fuel Use: The fossil fuel footprint of a copper azole-treated wood deck is equivalent to driving a car 40 miles/year. In comparison, the fossil fuel footprint of a typical wood plastic composite deck is equivalent to driving a car 540 miles/year.
• Recoverable Energy: The carbon embodied in wood makes outof-service wood products excellent candidates for energy recovery. Treated wood can be used in cogeneration facilities or synthetic fuel manufacturing facilities as a non-fossil fuel source.
Treated Wood vs Steel and Concrete
Compared to steel and concrete, wood products undergo minimal processing, so the manufacturing phase requires far less energy and results in far less carbon dioxide emissions. Manufacturing steel is energy intensive and uses iron ore, which is extracted using open pit mining. During the process, carbon in the iron is reduced, causing carbon dioxide emissions thus adding to greenhouse gases.
Concrete is made mostly from other manufactured products, but the main ingredient is cement, which has the highest embodied energy as compared to other building products. Cement is made from limestone, which has to be blasted from surface mines, and sand. Mixing the two ingredients together requires heating with coal or natural gas at extremely high temperatures.
When it comes to transportation, wood is significantly lighter in weight as compared to other materials and is often locally produced. This means less transportation impact. Concrete also has the advantage of being produced locally, but it is heavy and has to be transported by truck. Steel is the heaviest building material.
Life Cycle Assessment
A Life Cycle Assessment completed by AquAeTer, Inc., concluded the following results on industrial treated wood:
• Less Energy & Resource Use: Preservative-treated utility poles require less total energy and less fossil fuel than concrete, galvanized steel, and fiber-reinforced composite utility poles. Preservative-treated utility poles require less water than concrete and fiber-reinforced composite utility poles.
• Lower Environmental Impacts: Preservative-treated utility poles have lower environmental impacts in comparison to concrete, steel, and fiber-reinforced composite utility poles for six key impact indicator categories: greenhouse gas pollution, net greenhouse gas, acid rain, smog, ecotoxicity, and eutrophication- causing emissions.
• Decreases Greenhouse Gas Levels: Use of preservative-treated utility poles lowers greenhouse gas levels in the atmosphere whereas concrete, galvanized steel, and fiber-reinforced composite utility poles increase greenhouse gas levels in the atmosphere.
• Offsets Fossil Fuel Use: Reuse of preservative-treated utility poles for energy recovery in permitted facilities with appropriate emission controls will further reduce greenhouse gas levels in the atmosphere, while offsetting the use of fossil fuel energy.
BuzZZZWords
Below are definitions of some common terms used in every day environmental discussions but often misused or misunderstood.
CARBON SEQUESTRATION. Carbon, which contributes to global warming, is pulled out of the atmosphere and put into long-term storage. While the world is looking for high-tech ways to accomplish this, the wood industry already practices this. Growing trees remove carbon dioxide from the atmosphere. Even after they are cut, the wood continues to sequester carbon.
CARBON FOOTPRINT. The release of carbon dioxide (CO2) during a product’s manufacture and use is ometimes referred to as its ‘carbon footprint.’ Coal, oil, natural gas and wood all contain solid carbon that becomes CO2 gas when the material is burned for energy. Because CO2 release contributes to climate change, and because of the need to conserve our energy resources, there is a desire to reduce the footprint of products and to choose products with a smaller carbon footprint.
The carbon footprint of a product can be calculated by measuring and categorizing all of the energy inputs. Calculating the carbon footprint of wood products requires special consideration. Woodmanufacturing uses a lot of bio-energy, the products store carbon, and wood products manufacturing is energy efficient. For these reasons, most wood products have negative carbon footprints – their use actually results in net carbon storage.
MANAGED FORESTS. A third of the U.S. is covered in forests and about 60% of those are privately owned, managed lands. Managed forests are part of a sustainable system that supplies the nation’s wood products while continually replenishing with new growth. During that 30+ year growth period, forestry professionals balance forest health including water and soil quality with the wildlife and fish that call the forest home and the community that surrounds the forest. Trees are harvested for many different purposes, but the responsible forestry and building industries use managed forest lands, replacing trees faster than they are removed.
SUSTAINABLE. A sustainable resource is one that can be replenished so that an ecological balance is maintained.
RENEWABLE. A renewable resource is one that is widely available, naturally replenished and has a low environmental impact.
RECYCLABLE. A recyclable object is one that, after its initial use, can be repurposed for another use. For example, treated railroad ties can be used for landscaping timbers. (might need a better example)
LIFE CYCLE ASSESSMENTS. Studies completed to assess environmental impacts associated with all the stages of a product’s life from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance, and disposal or recycling.
“Because of our vested interest in the land, we consider ourselves custodians of the forests.”
— Brad Croxton, 25-year forestry veteran and member of the treated wood industry
GREENHOUSE GASES. Any of various gaseous compounds (such as carbon dioxide) that absorb infrared radiation, trap heat in the atmosphere, and contribute to the greenhouse effect. The primary greenhouse gases in Earth’s atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone.
GREENHOUSE EFFECT. The greenhouse effect is the process by which radiation from a planet’s atmosphere warms the planet’s surface to a temperature above what it would be without its atmosphere.
EMBODIED ENERGY. The energy consumed by all of the processes associated with the production of a building, from the mining and processing of natural resources to manufacturing, transport and installation of products used in construction, makes up embodied energy. It can be useful in determining the effectiveness of energy-producing and energy-saving devices, or the “real” replacement cost of a building. And, because energy inputs usually entail greenhouse gas emissions, evaluating embodied energy is also useful in deciding whether a building contributes to or mitigates global warming. One fundamental purpose for measuring this quantity is to compare the amount of energy produced or saved by the product in question to the amount of energy consumed in producing it.
*Excerpt from chart on www.yourhome.gov.au/materials/embodied-energy
Some Frequently Asked Questions
What is a renewable natural resource?
A natural resource is renewable if it can be replaced at the rate at which it is consumed.
What building materials are considered renewable?
Trees are considered renewable as they are harvested for use in the building industry while new trees are being planted at the rate of about three trees for every one that is cut. The growth cycle lasts 30+ years during which the managed forest land is overseen and cared for by forestry professionals. Concrete ingredients - sand and gravel – are mined but not naturally replenished in a reasonable time period. With steel, the primary ingredient is iron ore and it cannot be replenished in a timely manner.
What is the difference between clear cutting and thinning?
Thinning removes underbrush and smaller trees to give more opportunity for the remaining forest to be nourished by the sun. The thinning process usually takes place when a tract of managed forest is about 18 to 20 years old. Once thinned, the trees continue to grow for at least 10 to 20 years before they are harvested and the land is prepared for new saplings to be planted. Clear cutting is removal of all trees and underbrush from a forested area. In managed forest lands, the trees are harvested at the peak of their life cycle in small tracts of land at a time. The soil is prepared and the land is replanted with a new crop of trees that will thrive over the 30+ year growth cycle.
What happens to by-products from tree thinning and harvesting?
Nothing is wasted. The underbrush or “unmerchantable” growth is cut and used as a compost bed to protect and nourish the soil while it is awaiting new plantings. Other by-products from the cutting and trimming of trees include mulch and building products. This mulch is sent to paper mills or used in animal bedding. Pine bark is bagged or sold in bulk as garden mulch. Sawdust is used as a fuel product.
What percentage of carbon is wood?
As trees grow the storage of carbon increases to about 50% of the tree’s weight. At peak, trees are cut and become dry wood that stores the carbon. As the tree ages beyond its peak it stores less and less carbon. If the tree burns or decomposes it releases the carbon back into the atmosphere as carbon dioxide.
