Ying Tong Chen

Christina Cogdell

Des 40: S 2&3

November 30, 2016

Tree House Material Research

Living in a tree house, whether for peace and quiet to escape the busy society or simply get close to nature can be a dream for some people. However, not many people would pay attention to the process of building a tree house. The materials that will use, the energy that will consume and the waste that will produce when making a tree house is way more profound than the general idea of buying a lot wood, build it and the finish product. By breaking down the general materials a tree house would use, this will reveal the life cycle of the pressure treated wood, plywood and nails, which can education people to utilize the use of the materials around them.

Pressure treated wood is one of the main material for building a tree house. It’s often use for outdoor project since the chemical and pressure treatment can make the wood last longer and weather proof. It all start with the lumber process. There are two types of wood, hard and softwood. Hardwood is often use for cabinetry, flooring, trim work, paneling and door. On the other hand, softwood is use for studs, planks, decking, beams and more. In a managed forest, appropriate size of trees will be cut down and transport to a lumber mill to cut into different size. Most of the trees that are ready to be cut down are visually inspect by workers. Trees are most likely to be cut and trim with gasoline powered chain saw, or a more advance harvest vehicle which have a harvester head that can do both cutting and trimming at the same time. Tractor or yarder will be use to move the logs on to the truck. Those vehicles are powered by diesel.

Once the logs arrive to the mill, the loader will load the logs on to a conveyor bell to remove the bark, using either rosser head debarker or ring debarker. The rosser head debarker use spinning cutter head that go along the log’s length while the log is rotating. The ring debarker act similar to a pencil sharpener, the logs go pass the rotating ring of knives (Froome, 2004). Once the logs are debarked, the conveyor bell move the logs to the bucking saw to be cut into predetermined lengths. The length of the logs may be different from mill to mill and their customer’s need. The length, diameter and defect of the logs will be scan by the optical sensors. Then a computer map out suggested cutting pattern that would maximize the number of pieces of lumber. The computer operator then decides how the wood will be cut base on the computer information, but mainly on experience. A head rig saw will cut the first piece lengthwise from the log. This piece is called slab, which is the outer part of the log and have the curvature of the tree. The slab usually will be recycled and chipped for other uses like paper pulp. When all the pieces are cut, either small or large, will be trimmed to smooth out the edges.

Now the lumber would be dried to draws the moisture out of the wood in order to prevent decay. This process usually use kiln dried or just air-dried. Industrial kiln is most likely to be powered with natural gas. Using the air-dried method, the lumber would have about 20% moisture left in the wood. For kiln dried, the moisture content can be less than 15%. After the lumber is dried, it will go thought the final trim of the surface and edges. The finished lumber will now be sent to a lumber treatment company to do the last manufacture process. Before the lumber go for the treatment, it will go through the step of incising. Incising is when a sharp teeth wheel press into the lumber to create small gap, this allow the chemical to get better penetration into the wood (Hiziroglu). A load of wood will be put into a pressure treatment tank. When the tank is close, the vacuum will evacuate the air. Later, the tank will be filled with chemical preservatives and the pressure of the tank will also be increase. There is different type of chemical preservatives are used for the treatment. Some oil based wood preservatives are creosote, pentachlorophenol and copper naphthenate. Oil based wood preservatives are usually use for utility poles and railroad ties where there are not many human skin contacts. Water based wood preservatives like Chromated Copper Arsenate (CCA), Ammoniacal Copper Zinc Arsenate (ACZA), Alkaline Copper Quat (ACQ) are commonly used for resident applications since it will have human skin contact most of the time (Livingston, 2005). A lot of the chemicals can pose a risk to human health, in 2004 the Environmental Protection Agency ban CCA treated lumber for residential use, but still can be used for industrial purposes (Morrison, 2016). As long the chemical is absorbed into the wood, there should be no release of toxicity unless someone decide to burn the wood or inhale the particle. After several hours, the preservatives will be drain, and the vacuum will clean the excessive preservatives off the lumber. Finally, the pressure treated wood is finish.

To distribute the lumber to different industrial, residential or hardware stores within the U.S., train and truck are commonly use to distribute the material. Most of the train and truck use diesel as the fuel to powered. Once the wood arrives to the local store, the lumber will be purchase by contractor’s company or residents who need it to build tree house. When using the wood, it’s best to use any scrap as much as possible. Since the pressure treated wood contain chemical in them, to recycle them is actually difficult. It’s recommended not to burn, bury or grind it (“Guidance Document”, 2005). Burning the treated wood waste can impact the air quality and the chemical from the wood can contaminate soil and water. Some of the pressure treated wood can be use as fuel in some co-generation facilities, but most of them have to go to the designated hazardous waste landfill.

Plywood can be used for interior or exterior and the roof underlayment of the tree house, it’s easy and inexpensive material to use. Both hardwood and softwood can be used to make plywood, or the combination of both types of wood. There are usually three part of the plywood. The top or the surface that is use to be seen is the face, the middle layer is the cord and the back. To bond all the layer, adhesive is essential. There are two types of glue commonly used for plywood, Water Boiled Proof (WBP) and Moisture Resistant (MR) glue. WBP glue is mostly for exterior plywood and MR glue is for interior plywood (Pan, 2014). Glue are made from animal remain like bones or hides. To begin the process of making plywood, it’s very similar to the beginning of making pressure treated wood, it all started with getting the log. After gathering the logs from a managed forest, the logs will be trim and send to the plywood mill by trucks. Before the debarking, the logs will need to be soften by soak in hot water, steam or hot water spays. While the logs are hot, it will then load on conveyor bell to go through the process of debarking as pressure treated wood manufacture process. Then the logs will be cut into section and become peeler blocks.

The peeler blocks are now move to the peeler lather. The lather would be rotating the block on its long axis, meanwhile a knife mounted parallel on the log’s axis to peel a sheet of veneer. As the block’s diameter get to the size of 3 to 4 inches, the lather will eject the cord of the block and continues on to the next block. As the veneer moving out of the peeler lather, the veneer would be already cut into predetermined widths, standard size is around 4 feet wide. For the cord, it will be cut into the lengths of 4 feet 3 inches. Optical scanner will check for defects pieces and move then to a different pile, the others will be sorted by grade. The sorted veneers will go into a mechanical dryer, powered by electricity, to draw most of the moisture out and left around 10 to 20 percent moisture content, this will help the gluing process later on. Once the veneers are dried, it will emerge from dryer and stack by grade.

The gluing process, can be both manually or semi-automatically to glue the veneers together. The layer of the veneer will be stack crossway on top of the other each time. Let’s use three-ply sheet as the assembly process. First the back-layer veneer would go thought a glue spreader, then the cord layer will be put on top of the glued surface of the back-layer crossway. The whole sheet would go thought the glue spreader again and the top layer veneer will be put on top of the glued core crossway. Each finished piece will be stack to get ready for the press. The assembled plywood sheets will load on a hot press which can handle around 20-40 sheets at a time. As the press squeezes the plywood together, it will also be heated to 230 ºF to 315 ºF to cure the glue properly. This process usually takes around 2-7 minutes. The rough sheets will be unload from the press and move to the saw for trimming the uneven edges and cut into final size. Any defects will go thought the patch line to repair. The plywood then go thought the sanding line and inspection for final process. The finished sheets will be stamped with grade-mark, stacks in pile, and ready to be ship.

Just like pressure treated wood, plywood can be ship using truck and train within the U.S. When plywood arrive to the local store, consumers will purchase the type and number of plywood according to what they need it for. Similar to pressure treated wood, it’s the best to use any scrap plywood as much as you can. Unlike pressure treated wood, plywood can be recycle/reuse for different product or fuel. Scrap of plywood can be chipped and make into recycled plywood. Most of the plywood do not content any hazardous chemical, so is most likely to be safe to burn for fuel. The waste of the plywood should be drop off in any disposal sites in local area since it can be reuse and recycle.

The last important material for build a tree house is nail. Nail is use to secure the connection between wood pieces or bine two piece of wood together. Today’s most nails are made of steel, a material that’s strong and durable. The main raw material of making steel is iron and coal. Both raw materials require mining. Before these two materials combine, coal need to convert into coke. Coke is when coking coal put in a coke oven to force out the impurities, making the coal left with pure carbon ("How Is Steel Produced?"). To make steel, iron and coke will be put in a blast furnace, some fluxes like lime will also be add into the furnace to collect the impurities. Blast furnace is heated with hot air, which uses natural gas. The furnace heated up to 1100 ºC - 1200 ºC, melting the coke as well as the iron. The molten iron then will drain out of from the furnace, so is the impurities. So far the iron has around 4-4.5% carbon. Then the molten iron will go to the basic oxygen furnace, where scrap steel some flux will be added and oxygen is blown into the furnace. The temperature of the furnace can be 1700 ºC. The scrap steel will melt, the impurities oxidized, by then the carbon content is reduce to 0-1.5% (Bell, 2016). This create the molten steel. Sometime another process will be done, secondary steel making, which is to adjust the steel composition like adding or remove certain elements to meet the specification.

The molten steel will then go through the casting process. The liquid steel will transfer to the molds. The cooled mold would cause the steel to have a thin steel shell and solidify, but then guided rolls would withdraw the shell strand and fully cooled/solidified the steel. The strand will then be cut into desired length of billets to make into wire later on. The billets will then be form into wire rods using the hot rolling process which come out in coil of one continuous length. Those metal wires will transfer to nail manufacturers for further process.

To make the wires into nails. First, the coil of wires will pass the wire drawing process. The wire is pull by machine, which go through a series of drawing dies, this will reduce the wire to appropriate size. Then the wire is draw by the nail making machine. As the wire is draw from the coils, a pair of gripper dies hold the wire. The free end of the wire is struck by a mechanical hammer, forming the head of the nail. Meanwhile, a shaped cutter strike and cut the opposite end of the nail, forming the point. The gripper dies then released the nail and hold the upcoming wire and repeat the previous process. Some nails will be serrated or helical twists, depends on the demand of the customers. The nails will then be giving a finishing touch by put into a rolling drum of hot sawdust to polish the surface. The nails are then go to the packaging process, usually a box of nails can pack in 1, 5, 10, 25, and 50 pounds. Those steel nails are ready to be ship.

The shipping process is no different from the pressure treated wood and the plywood, it’s also using truck, train and ship across the U.S. Once is in the local hardware store, it will be purchase and use for building tree house and many other projects. When extra nails are left after a project, store them in a dry and cool place so that it won’t rust or use it for future project. Since nails are mostly made of steel or other metal, it can be recycled as scrap metal and can be use in different metal product making. Steel can contaminate soil overtime if expose to the soil directly, so collect as many nails as possible and drop it off in local metal recycle center (Sofilić, Bertić, Mežnarić, & Brnardić).

After doing research of the three materials a tree house use, we can see that no materials come by easy. Trees would be cut down and transform into pressure treated wood and plywood. Raw material like iron and coal come from earth will transform into steel and form into nails. Using all those materials, we were able to build beautiful tree house. At the same time, we need to understand that our resources are finite. Recycle and reuse can be an alternate method to save the mother nature, but will it last long?

Bibliography

Bell, Terence. "Modern Steel Manufacturing Process." The Balance. About, Inc., 7 Aug. 2016. Web. 30 Nov. 2016. <https://www.thebalance.com/steel-production-2340173>.

Blue, Jesscia. "How Do I Recycle Wood?" Home Guides | SF Gate. SFGate, n.d. Web. 30 Nov. 2016. <http://homeguides.sfgate.com/recycle-wood-79134.html>.

 Froome, Alan. "Sawmill Process Begins with Bucking, Debarking." TimberLine. Industrial Reporting, Inc., 1 Oct. 2004. Web. 30 Nov. 2016. <http://www.timberlinemag.com/articledatabase/view.asp?articleID=1215>.

Hiziroglu, Salim. "Basics of Pressure Treatment of Wood." Basics of Pressure Treatment of Wood (n.d.): 1-4. Oklahoma State University. Web. <http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2531/NREM-5047web%20color.pdf>.

Kozak, Bruce, and Joseph Dzierzawski. "Continuous Casting of Steel: Basic Principles." Steel Works. American Iron and Steel Institute, n.d. Web. 30 Nov. 2016. <http://www.steel.org/making-steel/how-its-made/processes/processes-info/continuous-casting-of-steel---basic-principles.aspx>.

Livingston, Jean. "What's In That Pressure- Treated Wood?" What's In That Pressure-Treated Wood (2005): 1-3. Forest Products Laboratory, 2005. Web. 30 Nov. 2016. <http://www.fpl.fs.fed.us/documnts/techline/whats-in-that-pressure-treated-wood.pdf>.

Morrison, Daniel S. "The New Pressure-Treated Wood." FineHomeBuilding. Fine Homebuilding, 09 Apr. 2016. Web. 30 Nov. 2016. <http://www.finehomebuilding.com/2004/01/01/the-new-pressure-treated-wood>.

Guidance Document Management and Disposal of Treated Wood Waste in California. (2005): 1-2. Western Wood Preservers Institute, July 2005. Web. 30 Nov. 2016. <http://www.wwpinstitute.org/documents/GuidanceDocumentforDisposalofTreatedWoodWasteinCalifornia.pdf>.

Pan, Mason. "What Is WBP Glue – Which Is Commonly Used for Plywood / Film Faced Plywood." China Wood Agency. China Wood Agency, 03 Aug. 2014. Web. 30 Nov. 2016. <http://www.plywood.cc/2007/10/25/what-is-wbp-glue-which-is-commonly-used-for-plywood-film-faced-plywood/>.

Pan, Mason. "What’s MR Glue-which Is Commonly Used for Plywood / Film Faced Plywood / Blockboard." China Wood Agency. China Wood Agency, 03 Aug. 2014. Web. 30 Nov. 2016. <http://www.plywood.cc/2007/09/25/what-is-mr-glue-which-is-commonly-used-for-plywood-film-faced-plywood-blockboard/>.

Sofilić, Tahir, Blaženka Bertić, Vesna Šimunić Mežnarić, and Ivan Brnardić. "Soil Pollution as a Result of Temporary Steel Scrap Storage at the Melt Shop." ECOLOGIA BALKANICA 5.1 (2013): 21-30. Ecologia Balkanica. Web. 30 Nov. 2016. <http://web.uni-plovdiv.bg/mollov/EB/2013_vol5_iss1/021-030_eb13101.pdf>.

"How Is Steel Produced?" World Coal Association. N.p., n.d. Web. 30 Nov. 2016. <https://www.worldcoal.org/coal/uses-coal/how-steel-produced>.

"Descriptions of Manufacturing Processes." FAO Corporate Document Repository. FAO, n.d. Web. 30 Nov. 2016. <http://www.fao.org/docrep/t0269e/t0269e03.htm>.

"Lumber." How Lumber Is Made. Advameg, Inc., n.d. Web. 30 Nov. 2016. <http://www.madehow.com/Volume-3/Lumber.html>.

"Nail." How Nail Is Made. Advameg, Inc., n.d. Web. 30 Nov. 2016. <http://www.madehow.com/Volume-2/Nail.html>.

"Plywood." How Plywood Is Made, Product, Industry, Machine. Advameg, Inc., n.d. Web. 30 Nov. 2016. <http://www.madehow.com/Volume-4/Plywood.html>.

Alex Lee      

Christina Cogdell

Des40 session2

Nov 30,2016

Treehouse Life-cycle

    Since childhood, I have always been intrigued by the whimsical dream of living in a treehouse. After all, who wouldn’t be enchanted by the fantasy of escaping reality and living high up surrounded by verdurous trees and wooden aroma? Therefore, when given the opportunity to conduct research of an open topic, our group was thrilled to embark the journey in exploring the making process of a tree house. Exciting as it was, our research nevertheless made us learnt that researching the process of manufacturing a treehouse is way more intricate than merely imagining living in a treehouse, for it could not be done without understanding the processes of acquiring raw materials, energy consumptions and wastes productions. Even though it is impractical to scrutinize all varying materials of myriad treehouses with different designs in the world, laying inspections upon the mechanical wood industry will suffice to unlock certain doors regarding what role energy play within treehouses, and hopefully ensues with the beneficial consequence of educating the public in terms of utilizing and choosing materials for construction purpose.

Material acquisition

     Materials of treehouses do not come out of thin air. Wood utilized in these buildings all derived from the mechanical forest industry. Therefore I will put the emphasis of this paper in understanding the process of energy consumed in this specific vast industry. Energy come in many forms, such as kinetic energy to chemical energy to hydraulic energy, and in the case of the mechanical forest industry, energy supplied to it primary comprised of heat and electricity (FAO). There are three general sources to attain electricity, one of them is through purchasement, the other by on-site generation, which is either generated by diesel ( or other gasoline-driven generators ), or by steam driven turbo-generators that are employed in co-generation plants, and lastly gained through the empowerments of electric driven-motors and natural lighting.

Heat is another big source of energy too. It primarily comes from the combustion of fuels such as oil, coal, natural gas and wood residue. These all provide tremendous amount of thermal energy required for process heating and drying of wood. Steam gas, heated water and thermal oil also acted as heating instruments and though steam (saturated) is acknowledged as one of the most efficient means to transmit thermal energy, heated water is generally utilized in small sized mills, especially in developing nations (AROLA). And during these years, direct-firing of veneer drying kilns and particle dryers have also served as good alternative sources of such form of energy.

Material acquisition

     Materials of treehouses do not come out of thin air. Wood utilized in these buildings all derived from the mechanical forest industry. Therefore I will put the emphasis of this paper in understanding the process of energy consumed in this specific vast industry. Energy come in many forms, such as kinetic energy to chemical energy to hydraulic energy, and in the case of the mechanical forest industry, energy supplied to it primary comprised of heat and electricity (FAO). There are three general sources to attain electricity, one of them is through purchasement, the other by on-site generation, which is either generated by diesel ( or other gasoline-driven generators ), or by steam driven turbo-generators that are employed in co-generation plants, and lastly gained through the empowerments of electric driven-motors and natural lighting.

Heat is another big source of energy too. It primarily comes from the combustion of fuels such as oil, coal, natural gas and wood residue. These all provide tremendous amount of thermal energy required for process heating and drying of wood. Steam gas, heated water and thermal oil also acted as heating instruments and though steam (saturated) is acknowledged as one of the most efficient means to transmit thermal energy, heated water is generally utilized in small sized mills, especially in developing nations (AROLA). And during these years, direct-firing of veneer drying kilns and particle dryers have also served as good alternative sources of such form of energy.

Material acquisition

     Materials of treehouses do not come out of thin air. Wood utilized in these buildings all derived from the mechanical forest industry. Therefore I will put the emphasis of this paper in understanding the process of energy consumed in this specific vast industry. Energy come in many forms, such as kinetic energy to chemical energy to hydraulic energy, and in the case of the mechanical forest industry, energy supplied to it primary comprised of heat and electricity (FAO). There are three general sources to attain electricity, one of them is through purchasement, the other by on-site generation, which is either generated by diesel ( or other gasoline-driven generators ), or by steam driven turbo-generators that are employed in co-generation plants, and lastly gained through the empowerments of electric driven-motors and natural lighting.

Heat is another big source of energy too. It primarily comes from the combustion of fuels such as oil, coal, natural gas and wood residue. These all provide tremendous amount of thermal energy required for process heating and drying of wood. Steam gas, heated water and thermal oil also acted as heating instruments and though steam (saturated) is acknowledged as one of the most efficient means to transmit thermal energy, heated water is generally utilized in small sized mills, especially in developing nations (AROLA). And during these years, direct-firing of veneer drying kilns and particle dryers have also served as good alternative sources of such form of energy.

It is very frustrating for me to concede, but unfortunately, unlike most other industries, it is very difficult to obtain specific numbers and data of such energy as there exist much variations between one mechanical wood-processing plant and another, and the energy consumed in the production of lumber, plywood or particleboard are in nature site specific and masked. International comparisons of energy consumed per unit of product, leveled on a national average standard, are much difficult to grasp due to deviations in data recording and disclosure. Furthermore, greater discrepancies exist not only because of the mentioned causes, but stemmed from diverging proportions of mills that kiln dry their lumber, variations in wood species, dimensions, fluctuating climatic conditions and so on all could influence the embodied energy. Although one might be by the gloomy outlook, we can look at the equally diverse ranges of energy derived from dissimilarities between mills. Sawntimber (air-dried) is 0.06 to 0.2 GJ/m3. Sawntimber (kiln-dried) is 1.00 to 2.85 GJ/m3. Plywood is 4.00GJ.

Manufacturing, Processing and Formulation

Energy consumption of manufacturing process in the mechanical forest wood industry mostly took place in three primary divisions- Processing and materials handling; raw material and product drying; services like compressed air, space heating and lighting premises. Moreover, the energy requirements of different species of wood are as the following. Sawntimber (air-dried): (Electrical) 30kwh/m3 hardwood and 20kwh/m3 for softwood. Sawntimber (kiln-dried):  (Electrical) 75kwh/m3 for hardwood and 25kwh/m3 for softwood. (Thermal) 2.5 GJ/m3 for hardwood and 1.5 GJ/m3 for softwood. Pywood : (Electrical) 230kwh/m3 for hardwood and 150kwh/m3 for softwood. (Thermal) 6GJ/m3 for hardwood and 4GJ/m3 for softwood. Particleboard: (Electrical) 160kwh/m3 for hardwood and 120kwh/m3 for softwood. (Thermal) 3GJ/m3 for hardwood and 2GJ/m3 for softwood. Additionally, the average energy utilizations in only plywood production could also be found, which are 5.55 GJ/m3 for thermal energy and 0.83GJ/m3 for electricity energy. The numbers are pretty rough according to the source (Costock), but it still it gives us a general idea of energy consumption within the process.

Among all these three product manufacturing processes, thermal energy is so far the greatest user of energy, representing around 82-87 percent of the total energy requirement in the manufacture of sawntimber, plywood and particleboard, with drying accounting for about 87 percent, 61 percent and 62 percent respectively (KOCKUMS).

Log sawing, veneer peeling and particle reduction are the dominant users of power, representing approximately 27 percent, 23 percent and 30 percent of the manufacturing processes' total electrical requirements. In all three processes, materials handling certainly uses an profuse amount of electricity, accounting for 1528 percent. Such services as lighting, space heating, hot water or steam systems, compressed air and workshops facilities do not represent a large power user, yet in collective terms their energy needs are rather tremendous.

Transportation and Distribution:

After arriving upon one mill’s storage yard, logs are distributed and placed in accord to their specific diameter, length and species etcs. Sufficient quantities are piled up to ensure the sawmill’s continuous operation, especially during bad weather conditions in time of log extraction and supply from forest might be detrimentally inflicted.

Transportation and handling of logs differ between individual mills. They greatly depend upon the cap space of sawmill operation and the size of receiving logs as well. Manual and animal power, in form of kinetic energy, usually are employed in throughout the range within small sized sawmill units, from log-carrying front-end loaders to overhead cranes.

Energy consumed in megajoules per ton of plywood shipped in a distance of a mile (Argonne National Lab) is most efficient in the forms of ocean shipping and rail transporting, in which rail transport embodies 0.37MJ/ton-mile while ocean shipping takes up 0.23 MJ/ton-mile.

On a side note, drying and decreasing the moisture content to an acceptable level increase the value of timbers since they become dimensionally stabilized while having their strength in color significantly advanced, but also by decreasing the weight entails the decline in transport costs.

Use/ Reuse/ Maintainence:

There is usually no energy involved in this phase.

Recycle:

The forest wood industries are lucky enough to do recycling, unlike many other industries. In mechanical wood processing the greater part of thermal energy requirement could be reached by available residues. The plywood industry has the ability to create an excess amount of heat and electricity and so could support energy deficient processes in relatively more complicated producing such as lumber, plywood and particle board. In rural area, it could mean supplying extra energy for the needs of surrounding community as well.

Sawmilling and plywood industries each engender between 40 to 55 percent of waste from their incoming wood supply, with heat values around 17 to 23MJ/kg (dry weight), which is more than enough to reach their energy requirement. Sawmilling,veneer, plywood and particleboard production also provide maximum benefit from the usages of residues as raw materials and fuels, in which surplus energy could be exploited to leverage its economic and practical advantage (EKONO OY).

Residues of plywood have their recycle outlets; they could be turned into peeler log cores, core chips, lumber manufacture, pulp manufacture and veneer chipping and chips, all of these could serve as fuelwood and building materials for local inhabitants.

The heating value of wood , again, greatly depends upon its own species and which part of the tree is used. In general, softwoods have higher values than hardwoods with an average of 21 MJ/kg BD for resinous (ability to resist moisture and heat) woods and 19.8MJ/kg BD for other woods being used. It is shown the divergence of resin content within wood, normally with a value of 40 MJ/kg BD that accounts for the differences in values between species, whereas there exist little differences in heating values of the wood substance itself (ESPRING).

Waste Management:

It was said that it was technically reachable to use wood waste as fuel for power generation. Yet sadly economics probes to be one great hindering border in many circumstances. Even though there are conspicuous profits to be exploited in the outcome of burning wood residue to decrease one manufacturer’s fuel and electricity bill, they are drowned by high capital costs, low plant efficiencies and manning levels (FAO ). As the mechanics of wood waste energy becomes more attractive as fuel price increases, the investment and operating cost of the plant are needed to take into account of transforming into other useable energy before making further assumptions. Despite their the ability to serve its own power with its own fuel, it is thought to be economically unjustified for one plywood plant less than 150000M3/A log input capacity to make their own source of power, unless they’re interrelated with other industries such as particleboard production or individual sawmills. (Lengel)

References:

Pan, Mason. "What’s MR Glue-which Is Commonly Used for Plywood / Film Faced Plywood / Blockboard." China Wood Agency. China Wood Agency, 03 Aug. 2014. Web. 30 Nov. 2016. <http://www.plywood.cc/2007/09/25/what-is-mr-glue-which-is-commonly-used-for-plywood-film-faced-plywood-blockboard/>.

LENGEL, D.E. 1976. How to Reduce Energy Requirements in New and Old Installations. Wood Residue as an Energy Source. Madison, Wisconsin, Forest Products Research Society

AROLA, R.A. 1996. Wood Fuels - How do they stack up? Energy and the Wood Products Industry. Madison, Wisconsin, Forest Products Research Society.

"Plywood." How Plywood Is Made, Product, Industry, Machine. Advameg, Inc., n.d. Web. 30 Nov. 2016. <http://www.madehow.com/Volume-4/Plywood.html>.

EKONO OY. 1980. Power and Heat Plants. (Study prepared for the FAO portfolio of small-scale forest industries for developing countries.) Helsinki, Finland.

ESPING, B. 1992. Energy Saving in Timber Drying. (Paper presented at seminar on Energy Conservation and Self-Sufficiency in the Sawmilling Industry. Bonn, United Nations Economic Commission for Europe.)

PINGREY, D.W. 1986. Forest Products Energy Overview. Energy and the Wood Products Industry. Madison, Wisconsin, Forest Products Research Society.

COMSTOCK, G.L. 1976. Energy Requirements for Drying of Wood Products. Wood Residue as an Energy Source. Madison, Wisconsin, Forest Products Research Society.

Natalie Li

DES 40A – A02

Professor Cogdell

11/29/2016

Waste and Emission – Commercial Type Tree House

Since the mid-1990s, the popularity of building a tree house has increased in the U.S.  The increase of disposable income, and the rise of interest in the environmental affair, which included sustainable living, are two of the main reasons that risen popularity of tree house building (Henderson). As the popularity of tree house is growing among the world, there are more commercial organizations building their business based upon this idea, such as a tree house hotel, a restaurant, or a museum, in order to raises the customer’s interest and maximize the profit earning of an organization. There are three materials that are commonly use in the construction of a commercial type tree house: plywood that could be used for both interior and exterior of a tree house; and pressure treated wood is mainly for building a treehouse’s structure; also, the nails for tighten wood blocks. To have a general idea on the waste and emission that could be produced by these three types of material is useful for preventing people to harm the environment while building a commercial type tree house. Since people would always underestimate the amount of pollution that we would potentially contributed to the whole life cycle of making a tree house, it is significant for us to have a comprehensive examination on the aspect of its waste and emission.

Plywood:

Among all the materials used in constructing a tree house, plywood is one of the most common and widely used materials as it is much cheaper than solid wood and is in some way stronger than solid wood. Plywood is manufactured by gluing several thin layers of hardwood trees’ wood together using phenol-formaldehyde glue. According to an article in Nature, plywood has become one of the most common construction materials in the Indian construction industry. Despite the lack of case studies showing tree houses that are made by plywood, numbers of studies had suggested the possibility of plywood taking over other wood-ly materials in terms of constructing a house or buildings (The Coming of Plywood - A Revolution in the Utilization of Timber). Plywood can be used either on the exterior or interior of a tree house. Although plywood was made by using formaldehyde-formulated glue, which can cause allergic problems to a specific group of people, studies have proved that using plywood for a roof deck or for sheathing under siding will seldom cause any damage to one’s health as long as the house is very widely-constructed and the plywood is separated far enough from the living space. When plywood is used for subfloor, an aluminum-foil diffusion retarder will usually be placed between a plywood subfloor and a hardwood finish floor so to block the potential problem that can be caused by the formaldehyde. Besides subfloors and root deck, plywood can also be used as the materials for furniture, cabinetry, and wall paneling (Bower).

According to Widarmana’s research (in 1984), waste produced via plywood industry is contributing to 57% of the whole waste produced by wood processing (Widarmana). It is very hard to isolate a certain step out from the whole plywood manufacturing process and said that it is solely contribute to the production of waste during the plywood production, as almost all the steps involved in the process are contributing to production of both solid and liquid wastes (Mintarsih). Solid wastes produced by plywood manufacturing include but not limit to log salvage, sander dust, glue solids, glue spills, and polyester coating. While water wastes produced include but not limit to the adhesive type of urea formaldehyde, kaolin, catcher, and bassilium. Both of the solid and liquid wastes are hugely influenced by the amount of workers used in the industry, as the plywood industry generally uses a large number of human resources. Therefore, besides the well-known chemical solid and liquid wastes, we cannot exclude the domestic solid and liquid wastes produced by the labor force, such as paper, plastic, and water waste due to the cleaning process, and so on (Darni Subari).

With all the wastes produced during the manufacturing of plywood and also all the potential waste produced during the construction of a tree house using plywood, it is not hard for the public to try to discover the possibility of recycling all those plywood wastes and re-using them. Getting into the 21st century, recycling acts on wood wastes have been developed tremendously. Recovered wood can be re-processed into some other products like medium density fiberboard and particleboard. They can also be ground for fuels or mulch. In addition, the Environmental Protection Agency (EPA) had proposed a policy to re-manufacture the chemical treated wood wastes and use them on some residential applications like play structures and picnic tables (Falk and McKeever). Considering that formaldehyde is not a very adhesive chemical, the process of removing the chemical out from the plywood and re-using them on the recreational project maybe a good way to reduce waste damage.

Pressure-Treated Wood:

Pressure treated wood has been widely used for the construction of a tree house structure due to the allowance of increasing resistance to rot and insect attack (Fulton). Most untreated wood will decompose by having insect attacks and decays due to four following conditions: high moisture, a favorable temperature, oxygen, and wood fiber as a food source for the insects. To use pressure-treated wood products to eliminate the wood fiber is a practical way to prevent insect attacks; if wood can be treated with a proper method, it expected to be last for decades (Guide to Pressure Treated Wood). Basically, there are three types of preservatives that are broadly used for the pressure treatment of wood: firstly, waterborne preservatives; secondly, oil-type preservatives; and thirdly, the creosote preservatives. The waterborne preservatives are generally used for most residential and commercial building applications. By forcing the chemical preservatives into the wood’s cells within a closed pressure-cylinder, this pressure-treating process is viewed as a highly-controlled process. During the treating cycle, it consists of chemical reaction within the wood’s fiber; the time for maximizing fixation of the preservatives could take several hours to a few days, and it depends on humidity, temperatures, and seasonal conditions. This chemical reaction makes the treated wood to have ability to resist the attack of insects, decay, fungus, and marine borers (Guide to Pressure Treated Wood). 

Furthermore, researching the chemical emission of pressure-treated wood is a crucial consideration when we planning to build a commercial tree house due to its impacts on both human’s health and the environment. In the article, “Glossary of Treehouse Terms,” written by TheTreeHouseGuide, the pressure-treated wood used to contain arsenic compounds which could be transferred to skin on contact; if using this preservative in large quantities, it could harm people’s health. One of the most common types of treated lumber is impregnated with chromated copper arsenate (also known as CCA). The CCA lumber is popular due to its inexpensive cost, and its effective resistance. Even though the producer claims that it is safe to use CCA lumber for construction, the wood is treated with chromium, copper, and arsenic, that these three chemicals are all toxic (Lamp'l). Moreover, besides the chemical compounds that emits from the material during the treatment process, the treated wood debris that produced by trimming is considered to be a solid waste. Although it is illegal that individually burning the CCA treated wood in construction sites, people use the treated wood debris as scrap firewood. This illegal action causes a highly release of toxic chemicals into the air, and the inflamed ashes contain a huge amount of arsenic that could be easily inhaled (Lamp'l).   

Additionally, there is a narrow circle of evidence that shows about the reuse of the pressure treated wood because of the preservatives that use for wood pressure treatment consists of toxic chemical compounds. Only a few types of pressure-treated wood could be reused as fuels under specific approval that acknowledged by the co-generation facilities (Management and Disposal of Treated Wood Waste in California). Besides, the article “the Reuse of Treated Wood,” the author, Smith shows that there are barriers to recycle the treated wood as the contractors are disposing the treated wood waste in the landfills due to its convenience and inexpensive cost, and they have a low awareness on the harmfulness that the treated wood could cost to the environment (Smith, Bailey and Alderman). As for the waste management aspect, the correct way of disposing treated wood waste is an important view that we should examine on. Instead of discarding the material on the land or burn it through an illegal way, it should be delivered to a permitted landfill [wwp guidance]. Currently, the most proper and eco-friendly way to dispose treated wood waste is the delivery on a landfill that has protective liners. The liners could decrease the possibility of seeping of contaminants into ground water. Compared to the disposal into unlined landfills, this method is a much safer disposal. Otherwise, disposing the CCA treated wood incorrectly will result in a serious environmental problem. However, the arsenic compound has been phasing out in the consumer market in the U.S. Alternatively, people use the heat treatment, which is a form of wood protection that is not involving any extra chemical (Guide to Pressure Treated Wood). 

Nails:

It is not hard to imagine how tough building a house will be without using a nail. Nails can be found in almost everywhere and are able to be used in any process during construction. For example, nails are used to pin two separated wood-made boards together; nails are used to create a point for holding a certain project; nails are used to hold a certain project in place by pining it onto an unmovable object. It is not hard to see how much we are relying on nails in our construction works. However, the nails-making process can be a serious problem toward the environment and the society if it is not being controlled well. One of the biggest pollutions from nail-manufacturing is the air pollution. In order to make a steel complex for nail modelling, steel core will have to be heated up with carbon (coal mostly). This heating process will produce a lot of different greenhouse gases like sulfur dioxide, nitrogen oxide, and carbon dioxide. All these greenhouse gases are found to be responsible for the global warming problem (Climate Change 2014: Synthesis Report. Summary for Policymakers). Besides the global warming problem, numbers of biological studies had also shown that all the greenhouse gases emitted from the nail-manufacturing process will lead to different kinds of health problem, such as cardiovascular diseases, lung problems, and more serious brain damage.

In addition to air pollution, nail production can also lead to the formation of a lot of solid wastes. As the steel is being made and cut into a nail-shape, small pieces of steel will be cut off and trashed. Those steel, as after combustion with coal, can release a lot of toxic chemicals to the environment. For example, nickel (one of the most common metals found in nail-manufacturing industry waste) was found to be able to adhere onto vegetables if the wastes are dumped into areas closed to farmland. Human who eats vegetables that contain nickel can lead to serious corrosion process within their digestion system (Grandjean). Another common toxic metal aluminium can be easily spread into soil and water if the metal wastes from the nail-producing process are not treated carefully. This can result in an increase in aluminium level in those vegetables and fishes that are living in the polluted areas. Human eating those aluminium-polluted vegetables/fishes was found to have a certain level of DNA damage (Mihaljevic, Ternjej and Stankovic). Despite the possible pollution from making nails, the government has proposed a series of policies which forcing the industries to recycle the solid wastes that are produced during the nail-manufacturing process and hope that this can help to minimize the pollution caused by producing nails.

As the commercial type tree house is being more popular, examining on the waste and emission of materials for building a tree house has considered to be a significant step for people as a reference when they are deciding to have a tree house construction. The waste examination of a tree house could be effectively alleviated the burden on our environment. Through researching on the waste and emission aspects of a commercial tree house with the guidance of the Product Life- Cycle Diagram, it is easily for us to see that from raw materials acquisition, to the waste management, almost each of the process shown that there are certain forms of waste and emission that could cause a damage to the environment or even to human’s health. Unfortunately, there is a lack of research showing of the waste and emission of the distributing and transporting process for a tree house building. To say it simply, this type of architecture is not as eco-friendly and sustainable as people think when we get to the depth of the research on waste and emission of the materials for tree house building.

References

Bower, John. Plywood. 5 April 2010. 27 11 2016.

"Climate Change 2014: Synthesis Report. Summary for Policymakers." 2015.

Darni Subari, Dr. Ir. Hj. "Effectiveness of Liquid Waste Management in Plywood Industry in South Kalimantan." Journal of Environmental Science. Toxicology and Food Technology (2014): 28-33.

Falk, Robert H. and David B. McKeever. "Recovering Wood for Reuse and Recycling - A United States Perspective." Thessaloniki (2004): 22-24.

Fulton, Patrick. Glossary of Treehouse Terms. 2015. <http://www.thetreehouseguide.com/glossary.htm#heatpreservation>.

Grandjean, P. "Human exposure to nickel." Europe PMC (1984): 469-485.

Guide to Pressure Treated Wood. Vancouver, WA: Western Wood Preservers Institute, 2011.

Henderson, Paula. "Adam Mornement." Treehouses (2005): 7.

Lamp'l, Joe. Dispose of Pressure Treated Lumber Properly. 23 7 2010. <http://www.growingagreenerworld.com/dispose-of-pressure-treated-lumber-properly/>.

Management and Disposal of Treated Wood Waste in California. Vancouver, WA: Western Wood Preservers Institute, 2005.

Mihaljevic, Zlatko, et al. "Application of the comet assay and detection of DNA damage in haemocytes of medicinal leech affected by aluminium pollution: A case study." Environmental Pollution (2009): 1565-1572.

Mintarsih, Tuti Hendrawati. "Panduan praktis pengelolaan lingkungan industri plywood." Asdep Bidang Pengendalian Pencemaran Agro Industri Kementrian Negara Lingkungan Hidup (2006).

Smith, Robert, et al. "The Reuse of Treated Wood." Townsend, Timothy G. and Helena Solo-Gabriele. Environmental Impacts of Treated Wood. New York: Taylor and Francis Group, 2006. 349-366.

"The Coming of Plywood - A Revolution in the Utiliztion of Timber." Nature (1943): 651-653.

Widarmana, S. Kini menanam esok memanen. Bogor: Lokakarya Pembangunan Timber Estate. Dakultas Kehutanan Institut Pertanian Bogor, 1984.