![\"s1\"](\"http:\/\/141.23.68.248\/wp\/wp-content\/uploads\/2024\/02\/s1.png\")
<\/a><\/p>\nThe energy required for wood harvesting, initial processing, beam production, construction, and beam maintenance will be quantified, as well as the emissions from those lifecycle stages. Due to time constraints and limited data sources, the potential energy reclamation often associated with wood products will be excluded.<\/p>\n
3. Design Options<\/h3>\n
Each beam type has a different configuration of wood components, resulting in various types of cross sections. Cross-Laminated Timber (CLT) is composed of wood studs oriented so that the grain of each layer is perpendicular to that of the neighboring layers. By contrast, the wood grain of each Glue Laminated Timber (GLT) layer faces the same direction throughout the beam. The final beam type, Laminated Veneer Lumber, is composed of many layers of thin wood veneers, typically about 3-5mm thick.\u00a0For our study, we will analyze the following three design options:<\/p>\n
We define the materials as shown in the table below. All beam types are assumed to be hardwood, fully-edge glued, and placed under typical loading patterns for a residential building. The functional unit is a 1 meter long beam span. Assume for the GLT and CLT beams that each layer is \u2155 th of the cross-section width (Balasbaneh, A. Sher, W.), and for the LVL beam that veneers are 3mm layered lengthwise (Lu, H.). The fastener cross sections are calculated as if folded flat, with two plates on either side and one set of fasteners for each end of the beams. Bolts and screw weights are included.<\/p>\n At the end of the beam\u2019s lifetime, we can total the amount of energy and emissions used in the process for each material component. For this report, we will analyze the embodied energy, the amount of \ud835\udc36\ud835\udc422 , and emissions. The wood studs used for both GLT and CLT\u00a0 \ud835\udc41\ud835\udc42\ud835\udc65 \ud835\udc46\ud835\udc422 were deemed comparable (Demirovic, E.), although from one study we find that the overall production of CLT studs use 40% less Energy than GLT, and 22% less \ud835\udc36\ud835\udc422 than GLT (Balasbaneh, A. Sher, W.). The LVL veneers are assumed to be 3mm (Puettmann, M.).<\/p>\n \u00a0<\/a><\/p>\n The lifespan of a typical timber-framed residential building is around 100 years, as confirmed in multiple sources and the Fault-Tree project associated with this report. During this lifetime, there are several maintenance and repair events that a beam system may need to undergo. We assume that GLT and CLT beams are similar enough to require the same frequency of beam-specific maintenance, and that the thicker bolts used in the plate fasteners\u00a0are more durable than the threaded screws in the timber brackets. The interventions are summarized in the following table:<\/p>\n We can now sum the energy and emissions consumed in the processing, machining, construction and maintenance for each beam design option. We use a beam length of 6 meters, for a representative residential housing span. The volume of materials is calculated for all beam and fastener combinations, and a matrix is created of quantities and intervention values for all three options.<\/p>\n From the graphs above, it is obvious that GLT consumes more energy and \ud835\udc36\ud835\udc422 than the other beam options, and that the LVL design option performs the best in most categories besides \ud835\udc46\ud835\udc422 emissions. That being said, it can be difficult to visually compare them in a way that allows a designer to make a confident choice in beam selection. It is therefore imperative that we conduct a multi-criteria decision analysis to select the best design option.<\/p>\n In this criteria analysis, different weights were assigned to the design options – both within the energy and emission categories, and to those larger four categories themselves.\u00a0In general, the lowest value column was favored highly, and equally valued columns were set to equal importance for simplicity. The \ud835\udc36\ud835\udc422 category was given the highest priority, as\u00a0our main goal was to analyze the carbon footprint of each beam. Energy was given the next highest priority. Similar to \ud835\udc36\ud835\udc422 emissions,\u00a0including end-of-life\u00a0would allow for incorporating energy recovery from burning wood waste and other such methods.<\/p>\n However, the values used in this project were from non-renewable sources so we therefore want to minimize the amount of these sources used as much as possible. The final two emissions were given similar importance levels, with \ud835\udc46\ud835\udc422 slightly lower as a larger portion of the contributions may have come from the steel. The overall results are displayed in the pie chart below.<\/p>\n<\/a><\/p>\n<\/a><\/p>\n4. Life Cycle Inventory<\/h3>\n
<\/a><\/p>\n5. Life Cycle Timeline<\/h3>\n
<\/a><\/p>\n6. Life Cycle Analysis<\/h3>\n
<\/a><\/p>\n7.\u00a0MCDM \u2013 Analytic hierarchy process (AHP)<\/h3>\n