Seeing the Forest for the Trees: Mass Timber and Climate Change

RESEARCH IN PRACTICE Spring 2021 Edition

SEEING THE FOREST FOR THE TREES

MASS TIMBER AND CLIMATE CHANGE

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Published April 2021 | New Orleans Cover Photograph by Alabama Cooperative Extension Office

TABLE OF CONTENTS

1. THE ENVIRONMENTAL PROSPECT OF DESIGNING WITH MASS TIMBER

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2. THE BUILDING SECTOR’S ROLE IN THE CLIMATE CRISIS

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3. USING RENEWABLE CARBON-BASED BUILDING MATERIALS

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4. WHAT IS MASS TIMBER?

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5. AN IMPRESSIVE OPPORTUNITY: MASS TIMBER’S CONTRIBUTION TO CARBON SAVINGS AT SCALE 25 6. HOW IS CARBON TRACKED?

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7. WHAT IS BIOGENIC CARBON IN CARBON ACCOUNTING?

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8. CONSIDERING FOR CARBON LOSSES

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9. SO HOW DO DESIGNERS PROCEED?

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10. CONCLUSION 47 REFERENCES

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Photograph by Government of Canada

1. THE ENVIRONMENTAL PROSPECT OF DESIGNING WITH MASS TIMBER

As new construction continues to meet the demands of an exponentially growing human population, architects and engineers (designers) play a pivotal role in reducing the carbon footprint of tomorrow’s built environment. Our industry remains the single greatest contributor to atmospheric greenhouse gas emissions that perpetuate the ongoing climate crisis. As operational energy consumption becomes increasingly more efficient in the modern building, embodied carbon emissions are a growing concern that stems from every material specified in our designs.

Emerging mass timber and engineered wood products stand as an exceptional, sustainable, structural material for four main reasons:

1. They require significantly less energy to produce than alternative structural materials

2. Their main material, wood, is a renewable resource unlike alternative structural materials

3. Wood sequesters carbon from the atmosphere during tree growth 4. If in high demand, they could accelerate the need for more sustainable forestry practice resulting in profound ecological benefits. Further research is needed to understand the impact of building with wood products at scale and how that can translate to a healthier building of tomorrow.

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Photograph by Think Wood

2. THE BUILDING SECTOR’S ROLE IN THE CLIMATE CRISIS

While irrefutable rises in global temperatures accelerate the intensity of extreme weather, natural disasters, and environmental degradation, all industries must re-evaluate business-as-usual practice in hopes of stemming the tide of the climate crisis. The building sector alone is responsible for generating 39% of annual global GHG emissions; further broken down, 28% attributed to emissions generated by the operation of our buildings and 11% associated with the emissions generated during the processes of extraction, construction, use, and disposal of building materials, known as embodied

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THE BUILDING SECTOR’S ROLE IN THE CLIMATE CRISIS

carbon [29]. Whereas operational emissions are projected to decline over time with building energy efficiency renovations and the use of renewable energy, embodied carbon has a less promising projection. There exists a global dependency on building materials that are fossil fuel intensive in production processes such as concrete and steel.

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THE BUILDING SECTOR’S ROLE IN THE CLIMATE CRISIS

In 2015 nearly every country around the planet pledged their commitment in a response to the threat of climate change in the Paris Agreement, by limiting average global temperature increase in the 21st century to 1.5 degrees Celsius above preindustrial levels. Prior to this international summit, consensus among climatologists was that average temperature increases beyond 2 degrees Celsius would result in irreversible, catastrophic effects in the form of droughts, sea-level rise, and increasingly devastating storms, therefore 1.5 degrees Celsius was established as a conservative unsurpassable benchmark. However, data shows that by 2015 human activity had warmed the planet by 0.87 degrees Celsius (± .12) above pre-industrial times, and if our current rate of warming continues the planet will reach human-induced temperature rise of 1.5 degrees Celsius by 2040 [28]. This staggering rate of warming shows that designers must consider renewable carbon-based materials over conventionally used mineral-based materials where possible.

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Photograph by U.S. Fish and Wildlife Service

3. USING RENEWABLE CARBON-BASED BUILDING MATERIALS

The forest is considered one of our planet’s major terrestrial carbon sinks, storing as much as 30% of annual anthropogenic emissions. Through the process of photosynthesis, trees absorb carbon dioxide (CO2) from the atmosphere and release oxygen (O2) while embedding the carbon (C) as complex carbohydrates in the tree biomass and soil. Carbon content accounts for 45-50% of a tree’s biomass of which roughly 70% is found in the aboveground biomass (the carbon in stems, stumps, branches, bark, seeds, and foliage), and 30% is stored in below ground biomass (the root system). Trees sequester carbon as long as they are actively growing but as trees reach maturity, they actively draw less CO2 from the atmosphere than during major periods of growth but remain invaluable for keeping carbon stored away in the tree’s biomass and out of the atmosphere. Carbon content will remain embedded until a tree dies and decays, or encounters natural disturbances such as forest fires, during which the carbon is immediately released back into the atmosphere.

The ongoing carbon exchange of drawing CO2 from the atmosphere to store in tree biomass, with an eventual release back into the atmosphere upon end-of-life, is referred to as the forest carbon cycle. This cycle differs from climate to climate in which warm humid regions promote the decomposition and subsequent carbon release much quicker than in cold, dry regions. For this reason, tropical forests become carbon neutral much quicker than boreal forests. We can prevent the decomposition of those forests by extending the life span of the trees in the form of wood products, where the carbon content remains in the woody matter until the product’s end-of-life stage during which carbon is released back into the atmosphere for eventual reabsorption by newly growing » PAGE 16 11

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USING RENEWABLE CARBON-BASED BUILDING MATERIALS

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forests. This incentivizes the production of longer lasting products to store the carbon for longer.

Reducing atmospheric CO2 levels is an environmental priority and we must shift to maximizing the time in which carbon is embedded in our wood products. This would require the reallocation of our timber harvests from short-lived timber products such as paper and pulp that quickly end up in waste bins, (with an average useful lifespan of 2.5 years), to long-lived wood products such as lumber, plywood, and engineered wood products found in the walls and structure of our built environment that can have a useful life span for 90 years or more [15]. We can further expand the life span of these structural wood products by designing them for disassembly. In 90 years as buildings need to be replaced, we could disassemble them by unfastening floors from girders and girders from columns and lift them out of place with a crane. Those same floors, girders, and columns could then be reused in a new configuration on site or elsewhere, preventing those elements from being incinerated or left to decompose and release their carbon back into the atmosphere.

The best case scenario for the forest carbon cycle is to keep a “closed loop,” meaning that the amount of carbon emitted by a tree or wood product at end-of-life is seamlessly offset by the CO2 absorbed by a newly planted tree growing simultaneously in the forest.

The “closed loop” is opened or breached when tree removals go unreplaced during log harvesting (deforestation) or land use change (forest transitions to agricultural land or is claimed for development) creating a carbon positive scenario in which emissions exceed removals. Inversely, if the life of a wood product exceeds the time in which it takes for a tree to reach merchantable maturity then a carbon negative scenario unfolds where removals exceed emissions. [16]

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USING RENEWABLE CARBON-BASED BUILDING MATERIALS

Photograph by Acton Ostry Architects 17

Mjøstårnet is an 18-storey mixed-use building in Brumunddal, Norway. Photo by Nina Rundsveen

4. WHAT IS MASS TIMBER?

Mass timber is a generalized term defined by a primary load-bearing structure made of either solid sawn or engineered wood products (EWP). The use of solid sawn or heavy timber construction already has an extensive history, but emerging EWPs hold increasing promise as 21st century building materials. These new building materials include an array of composite products made of dimensional lumber, wood strand, veneer, or wood fiber, bonded by high strength, moisture resistant adhesives. Depending on the specific product, contemporary EWPs such as glulam, cross laminated timber (CLT), dowel laminated timber (DLT), mass plywood panels (MPP), laminated veneer lumber (LVL), or » PAGE 22 19

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WHAT IS MASS TIMBER?

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parallel strand lumber (PSL) hold greater strength than steel pound-for-pound. Some products (CLT and MPP) have bi-axial spanning capabilities; and with the aid of elaborate formwork, products like glulam, LVL, and PSL can take sophisticated, expressive shape.

Most EWPs are made as an assembly of smaller members and therefore boards are mechanically inspected and easily sorted in terms of structural integrity. These are in turn placed optimally in the cross section of the EWP to achieve greatest strength. With the aid of finger joining technology EWPs can achieve greater length than ever with solid sawn timber.

In pursuit of proving the structural competency of emerging EWPs, rigorous testing by ad hoc committees of various mass timber building systems have proven adequate structural performance and fire resistance, prompting recent provisions to the International Building Code (IBC) 2021. These provisions allow the use of mass timber or noncombustible construction materials as primary structure up to 18 stories tall, creating a series of subsets to Type IV construction [12,13,14]. Advancements in code have allowed architects, engineers, and manufacturers to be confident that the mass timber industry will experience significant growth in years to come. In fact, a recent study claims that the number of buildings of this type will double every two years through the next decade [25]. The development and testing of new EWPs has provided architects with a variety of structural options that can act as both carbon banks and structure.

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WHAT IS MASS TIMBER?

Gul Hasan, Zoya. “Inside Vancouver’s Brock Commons, the World’s Tallest Mass Timber Building.” ArchDaily, 18 Sept. 2017

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Photograph by LEVER Architecture

5. AN IMPRESSIVE OPPORTUNITY: MASS TIMBER’S CONTRIBUTION TO CARBON SAVINGS AT SCALE The reality is that every building material requires a degree of energy consumption in the various stages of production. Designers are ultimately the individuals responsible for deciding which building material we choose; therefore, it is imperative that they are fully cognizant to the implications regarding carbon impact. Furthermore, looking towards renewable resources for building materials will stand integral in meeting the demands of the building sector, as the global population is expected to reach 9.8 billion by 2050, an increase of more than 25% from 2020. Additionally, the UN predicts that 66% of the world’s population will reside in urban areas by 2050, and upwards of 87% in the U.S. This projected densified living will require increased construction of both commercial and multifamily mid to high-rise buildings. Historically built predominantly of concrete and steel, these buildings are prime candidates for mass timber construction. Builders and designers alike have initiated multiple cutting-edge projects that prove this concept to be not only feasible but highly encouraging [8]. Furthermore, wood is distinguished as the only renewable material of the aforementioned structural materials and a considerable asset in the mitigation of GHG emissions due to its ability to sequester carbon.

We have previously discussed two ways that the switch to wood products reduces atmospheric carbon: carbon sequestration in trees and carbon storing in wood products.

A third way however to reduce atmospheric carbon comes from material substitution, or transitioning from mineral-based materials such as steel and concrete which generate more carbon emissions through their production processes than the wood product [25]. A study by CORRIM looked at this process and compared an unharvested forest to the overall impact of short harvest rotations with subsequent carbon banked in

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AN IMPRESSIVE OPPORTUNITY: MASS TIMBER’S CONTRIBUTION TO CARBON SAVINGS AT SCALE

wood products (all wood products from disposable paper plates to structural wood). Their findings showed that even though the resultant wood products and regenerated timber land did not quite sequester as much carbon as the unharvested forest, the benefit to avoided carbon through substitution was significant.

To better understand this impact, a peer-reviewed report analyzed 21 different studies that calculated the displacement factors of wood products substituted in place of mineral-based materials. They found that the average displacement factor was 2.1 tons of Carbon (tC), which means that for each cubic meter in wood products we are avoiding 1.9 tons CO2e. [26] This demonstrates tremendous opportunity for reducing carbon emissions from building materials.

To understand the potential environmental impact of using mass timber in lieu of concrete and steel, it’s worth assessing at a larger scale. Let’s look at a radical scenario where all urban construction for the next thirty years is built out of mass timber. According to the UN and U.S. Census Bureau, 89% of the U.S. population will live in urban areas by 2050, so we considered 89% of expected construction, set by the Energy Information Administration to be anywhere from three to four billion square feet annually, for this scenario. A series of existing mass timber projects were analyzed to determine an average volume of wood (.75 ft3/ ft2), carbon sequestered (46 lbs CO2/ft3), and carbon avoided (57 lbs CO2/ft3). The average volume of wood, multiplied by yearly square foot construction estimates

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and a timber waste factor, results in 4.7 billion cubic feet of wood annually required to account for all residential and commercial construction in urban areas moving forward.

An analysis of domestic timber stocks was performed to determine whether the supply could meet this demand. Based on USDA forestry data, findings showed that the current rate of annual increases in mature sawlogs, sizeable enough for producing mass timber, could supply up to 75% of all commercial projects, 91% of residential, and a combined 41% of commercial and residential projects in the urban setting (in terms of net volume needed, after waste from milling taken into consideration). It is worth noting that this is specifying an excess supply of timber, leftover after our current rate of domestic 28

AN IMPRESSIVE OPPORTUNITY: MASS TIMBER’S CONTRIBUTION TO CARBON SAVINGS AT SCALE

consumption, where there is significant opportunity to leverage that number if forestry practices were to move in a more sustainable direction. If that timber were allocated for use in construction, we could see as much as 1.4 gigatons of CO2 stored in our buildings’ structure and 1.8 gigatons avoided by using less concrete and steel every ten years. This equates to 691 million cars taken off the road for a year, or 58% of the current annual CO2 emission levels in the U.S.

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Photo by Marty Matheny

6. HOW IS CARBON TRACKED?

It is clear then that mass timber as a structural material can have a major impact on the carbon emissions related to the construction industry. Even as we know this can be true, architects still need a way to understand the emission implications during the early design phase of projects. Every material used in the construction of a building has a carbon footprint as they each require energy and resources to produce. Tracking these material inputs, outputs, and the amount of energy used can be applied in the form of an environmental performance report called a Life Cycle Analysis (LCA).

The analysis provides insight to a list of environmental impacts such as acidification, eutrophication, and global-warming potential (GWP.) Design software like Revit allows users to seamlessly imbue their Building Information Model (BIM) through the aid of LCA plugins like Tally, and quickly generate a highly informative report on the environmental impact of materials and products contained in their designs.

Architects can conduct whole building LCAs in various design phases to compare material options and identify areas for reducing the environmental impact of a building design.

Whole building LCAs will consider material procurement, construction, operation, and decommissioning (cradle-to-grave) as the system boundary.

Narrowing the focus, the life-cycle inventory (LCI) is the cradle-to-gate. This common accounting approach for various construction products ultimately informs the whole building LCA. For mass timber products, this LCI cradle-to gate system boundary includes forest operations and lumber milling (commonly accounted for in stage A1), transportation of all resources and materials (commonly accounted for in stage A2), and

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end-product manufacturing (commonly accounted for in stage A3). As most LCI software is highly nuanced and requires an in-depth level of data processing, LCIs are conducted by experienced practitioners typically at the request of product manufacturers. After collecting data relevant to resources consumed and emissions generated in all stages of production, practitioners will use a preferred LCI software for generating a performative analysis. The LCI is then used to create a concise, standardized, independently-verified report on the environmental performance of that product, known as an Environmental Product Declaration (EPD), useful on the consumer-end for comparing products within a category. EPDs are useful not only for architects and designers to compare the environmental impact of material options but allow manufacturers to identify and address major sources of CO2 emissions within their scope. Current EPDs work well for now, but we are perpetually learning and developing more accurate ways to track carbon in different systems. For wood this can be particularly challenging, because we have to account not just for emissions due to extraction and harvesting like mineral-based materials, but also for the positive effect of biogenic carbon through sequestration.

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HOW IS CARBON TRACKED?

Environmental Product Declaration: Table 2: LCIA Results Summary for Cradle-to-Gate production of 1 m3 of CLT

https://www.structurlam.com/wp-content/uploads/2021/02/StructurlamEnvironmental-Product-Declaration-CLT.pdf 33

Photograph by MSU Extension Service/Kevin Hudson

7. WHAT IS BIOGENIC CARBON IN CARBON ACCOUNTING?

Biogenic carbon is the natural cycle of sequestered carbon during photosynthesis and the eventual release of carbon at the end of a tree’s life. Current biogenic accounting standards for wood products state that all virgin or recycled wood, in addition to biofuel, enters the LCA system as having a global warming factor of -1 kg CO2e/kg CO2, and leaves the system (upon end-of-life scenario: combustion, biofuel, release during landfill decay, etc.) as +1kg CO2e/kg CO2. In other words, CO2 is counted as a negative number when drawn from the atmosphere but balanced by a positive equivalent in the form of

Bruce King’s A New Carbon Architecture; Arup / Bruce King 35

WHAT IS BIOGENIC CARBON IN CARBON ACCOUNTING?

CO2 emissions traced back to various stages of product manufacturing and its end-of-life fate; this balance of carbon sequestered equal to carbon released implies carbon neutrality.

Bruce King’s 2018 A New Carbon Architecture provides a theoretical framework that illustrates the environmental performance gap bet we en wo od produc t s sourced from sustainably managed forests versus unsustainably managed forests, insinuating significantly different carbon impacts. Up until recently, the difference between the two was viewed as simply as third party certifications being sustainable and state mandated regulations as unsustainable; however, not all certifications are equal, and each certification is not even equal in different regions of the United States.

Recent efforts by forestry data and analytics group Ecotrust have attempted to prove the performance gap between forestry practices through methods of utilizing remote-sensing datasets to conduct time-sensitive simulations.

Their study looked at 64 different forestland properties across Washington and Oregon to compare under a mix of “business as usual” compliance with state practice rules and FSC management. The study focused only on two performance standards of FSC certification

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Diaz, David D., et al. “Tradeoffs in Timber, Carbon, and Cash Flow under Alternative Management Systems for DouglasFir in the Pacific Northwest.”

MDPI, Multidisciplinary Digital Publishing Institute, 25 July 2018, www.mdpi.com/19994907/9/8/447.

critical to carbon impact: larger and more protective buffer zones around streams and leaving more live trees standing following harvests. Different rotation periods, (the time between the planting of a stand of trees and its final harvest), was a tested variable in the study which applied long rotations (75 years) and short rotations (40 years) to both forests operating under state practice and the more stringent FSC managed forest.

Results of the study showed that FSC management produced carbon storage ranging from 13-69% greater than business as usual under state practice [27].

After yielding these results, architecture firm Miller Hull Partnership teamed with Ecotrust Director David Diaz to further understand how this carbon storage study could telegraph into the wood products used in building designs. Ecotrust’s original research provided “upstream” carbon factors that were used to post process the LCA data from a Miller Hull design project to simulate the carbon impact of timber products sourced from forests under different management scenarios. This proved that a range of forest practices traditionally treated with the same blanket assumption of carbon neutrality can have wildly different outcomes if forestry practices are actually tracked. More research is needed to better understand and track these practices at an individual level to better incorporate into LCA tools.

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Keansburg, N.J., Aug. 19, 2013 -- Workers pile debris for pickup at a demolition site of a home damaged by Hurricane Sandy. The Keansburg demolition project, partially funded by the Federal Emergency Management Agency, expects to knock down 43 other condemned homes in area. Photograph by Rosanna Arias/FEMA

8. CONSIDERING FOR CARBON LOSSES

When considering other generalizations in accounting for biogenic carbon in LCAs, the national average for end-of-life scenarios may overlook multiple complexities in the disposal of timber products. The common fate for wood products at the end-of-life stage occurs either in the landfill (63.5% of the time based on national averages) where left for slow decay with potential for permanently storing as much as 50% of carbon for fossilization; the incinerator where wood is burned to generate energy (bioenergy) (22% of the time based on national averages), or recovered for reuse, recycling, or down-cycling (14.5% of the time based on national averages) [17,18,19,20]. The rate and amount of CO2 emitted by wood in the landfill depends on a litany of factors from waste management of the individual landfill, the composition of the wood products in the landfill, moisture content in the environment, compaction of landfill waste, and many more. [10]. It is also critical to note that in any anaerobic decomposition process the organic material generates methane (CH4) in addition to CO2, which if not captured and burned for energy (emitting CO2 in the process), is far more potent a GHG. Whether these landfill gases are contained or extracted also plays a major role in the carbon released during wood decomposition in landfills. [9,10].

Throughout the life-cycle of a timber product additional carbon losses occur. According to common logging practices, roughly 60% of the tree is extracted and transported to the mill during harvests, while 40% above and belowground biomass remains in the forest as dead organic matter (branches, stumps, roots, leaves) [1]. The leftover debris, or “slash is argued to provide a nutritive feedstock for future growth by enriching soils or a sustainable exchange of aerobic decay and carbon uptake [2].” The counter argument to

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CONSIDERING FOR CARBON LOSSES

the regenerative nature of slash is that it simply emits CO2 and CH4 upon decaying, just like if it were decaying in a landfill.

Alternatively, slash can be collected by loggers and brought to mills as a source of biofuel to supplement energy use in mill operations, offsetting fossil fuel/natural gas consumption. Mill owners often find this scenario impractical due to the costs associated with transporting the forest residuals. If the interest in reducing GHG emissions were translated into a monetary value fossil fuel emissions in form of carbon credits, however, this could be seen as a more viable option. This option would theoretically pay for the collection of forest residuals and demolition wood as replacements for existing fossil fuel use [3]. There is no one size fits all option for dealing with slash. Arguments side either with controlling the rate that carbon is released back into the atmosphere, (up to 20 years if left to decay vs. immediately upon burning for bioenergy), or weighing the benefits if left for decay vs. offsetting fossil fuel consumption with bioenergy [4]. It is important to call out that burning for bioenergy does stand heavily criticized by environmentalists for the high levels of particulate matter (PM) emitted when burning and the threat this poses to the public health of nearby communities. Studies show that compressed wood manufactured into pellets burns cleaner and reduces PM emissions [5,7].

An additional pathway for slash that is gaining notoriety among carbon researchers is biochar. This byproduct is produced when the wood is burned in the absence of oxygen, a process known as pyrolysis, resulting in a fine-grained, highly porous charcoal that help soils retain nutrients and moisture. Biochar also decreases the risk of wildfire, helps with insect and disease outbreak, and stores its carbon content from hundreds to thousands of years [6]. With increasing interest from the agricultural community, biochar is sold for as much as $1,500 per ton, an amount that if produced at scale could provide a substantial supplementary revenue stream for forest owners with a high carbon benefit [21]. One study suggests that as much as 12 percent of GHG emissions could be offset through biochar production [22].

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CONSIDERING FOR CARBON LOSSES

Plaven, George. “Machine Converts Forest Debris into Biochar.” Capital Press, 4 Feb. 2019, www.capitalpress.com/nation_world/science_and_tech/ machine-converts-forest-debris-into-biochar/article_cd95da56-24e8-11e9ad88-a361ce6d5a57.html.

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Rendering by LEVER Architecture

9. SO HOW DO DESIGNERS PROCEED?

The effects of climate conscious design by way of mass timber will only make a difference at an industry wide scale, but action starts with the individual architect. Here are several concepts that can fold into any design process with little effort:

CHANGE OUR DEFAULT MATERIAL SELECTIONS: Consult with engineers early on to see if timber is a viable option for meeting project code requirements. If so, prioritize FSC certified wood if possible as it currently shows demonstrated benefits in promoting climate-smart forests. If no, use less energy intensive building materials wherever possible. Reducing the building sector’s dependency on concrete and steel is the first step towards collective action in mitigation of the climate crisis.

DESIGN FOR LONGEVITY: When designing a new project, always consider how your building might serve another purpose 50-100 years from now. Will it house an entirely different programmatic function? If so, consider highly flexible and modular structural layouts that may be adapted and reused. Or is this design so program specific that it cannot be reappropriated for another function?

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SO HOW DO DESIGNERS PROCEED?

DESIGN FOR DISASSEMBLY: Also consider how the building can be reused, even as far as how elements could be taken apart easier. Work with fabricators and contractors to ensure that the building can be disassembled in the most simple means possible, where all wood can be recycled into future building projects. Part of this process will take intentional detailing and decision-making such as not pouring concrete directly on top of the wood platform or avoiding spray foam which is notoriously time consuming and difficult to remove in demo. These extra steps ensure a healthier building and greatly contribute to extending how long carbon is stored in each wood member.

ESTABLISH RELATIONSHIPS WITH MASS TIMBER PRODUCT SUPPLIERS: Reach out to product suppliers and ask as many questions as possible pertaining to the environmental performance and supply chain of all materials used in a design. This is the only way for suppliers to know the depth of client concerns. Product suppliers will not have all the information we hope to gain immediately, and that’s ok. A multitude of layers across multiple professions need to be peeled back to gain the information we are looking for. If designers consistently demand transparency for the forestry practices used, we can begin to uncover the carbon impact of forests at a much smaller scale.

ESTABLISH RELATIONSHIPS WITH CONTRACTORS AND BUILDERS: Encourage early communication and relationships with contractors to ensure that everyone understands the rational to using wood products over mineral-based materials. As EWPs continue to grow, particularly mass timber, more education will be needed for both designers and contractors. Designers have the ability to share robust documentation and solutions to typical concerns such as fire and acoustics and contractors will be able to confirm the feasibility of those solutions and share design solutions from past projects. Early communication will enable a better project overall.

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Rendering by LEVER Architecture

10. CONCLUSION

Endless research remains to fully understand the impact of using timber in a large-scale application, but upon examination of current proof points and reliable carbon emissions data, wood is demonstrably the better option than steel and concrete. Our industry contributes to greenhouse gas emissions unlike any other; and therefore, we have the ability to make a substantial impact through design. A path toward a healthier planet, one that is a better place for future generations, is in sight. It is up to designers to take a stance on the materials they use and the sustainability of those materials in hopes of reposing buildings from being the problem to becoming a solution in the climate crisis.

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REFERENCES

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Franklin, Jerry F., et al. Ecological Forest Management. Waveland Press. Long Grove, Ill. 2018

2

Bernheimer, Andrew. Organschi, Alan. Timber in the City. ORO Editions. 2014

3

https://corrim.org/wp-content/uploads/2017/12/CORRIM_Factsheet_ December_2013.pdf

4

Wagener, Willis W., Offord, Harold R. Logging Slash: its breakdown and decay at two forests in northern California. Forest Service & U.S. Department of Agriculture. https://www.fs.fed.us/psw/publications/documents/psw_rp083/psw_rp083.pdf

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Aurell, J., B.K. Gullett, D. Tabor, and N. Yonker. “Emissions from Prescribed Burning of Timber Slash Piles in Oregon.” Atmospheric Environment 150 (2017): 395–406. https://doi.org/10.1016/j.atmosenv.2016.11.034.

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Dave Levitan. December 9, et al. “Refilling the Carbon Sink: Biochar’s Potential and Pitfalls.” Yale E360, e360.yale.edu/features/refilling_the_carbon_sink_biochars_ potential_and_pitfalls.

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Ghafghazi, S., et al. “Particulate Matter Emissions from Combustion of Wood in District Heating Applications.” Renewable and Sustainable Energy Reviews, Pergamon, 5 May 2011, www.sciencedirect.com/science/article/ pii/S1364032111001365?casa_token=gY36i0-f48UAAAAA%3AguAc05t1uSU034e6TEXe48EMG4_Nokyn9lK-CJjSiEkF_Q2yUuIo_IeInToBbntuz68NP-LLg.

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Organschi, Alan et al. Timber City: Growing an Urban Carbon Sink with https:// www.researchgate.net/profile/Andrew_Ruff/publication/319109608_Timber_ City_Growing_an_Urban_Carbon_Sink_with_Glue_Screws_and_Cellulose_Fiber/ links/5991bcdca6fdcc53b79b072e/Timber-City-Growing-an-Urban-Carbon-Sinkwith-Glue-Screws-and-Cellulose-Fiber.pdf i

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NOAA Global Monitoring Laboratory. The Methane Cycle. https://www.esrl.noaa. gov/gmd/education/info_activities/pdfs/CTA_the_methane_cycle.pdf Micales, J.A., Skog, K.E. The Decomposition of Forest Products in Landfills.

International Biodeterioration & Biodegradation. Vol. 39. 1997. https://www.fpl. fs.fed.us/documnts/pdf1997/mical97a.pdf

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Beneš, Jaromír & Vondrovský, Václav & Ptáková, Michaela. (2014). NEOLITHIC LONGHOUSE PHENOMENON ORIGINS, MEANINGS, INHABITANTS AND SUCCESSORS. https://www.researchgate.net/publication/267024533_NEOLITHIC_ LONGHOUSE_PHENOMENON_ORIGINS_MEANINGS_INHABITANTS_AND_ SUCCESSORS

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Breneman, Scott et all. Tall Wood Buildings in the 2021 IBC Up to 18 Stories of Mass Timber. Woodworks – Wood Products Council. 2019. https://www.woodworks.org/ wp-content/uploads/wood_solution_paper-TALL-WOOD.pdf

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Zelinka, Samuel L. et al. Compartment Fire Testing of a Two-Story Mass Timber Building. United States Department of Agriculture. 2017. https://www.awc.org/pdf/ codes-standards/fire/WCTE-2018_Fire-Tests.pdf

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Osborne, Lindsay et al. Preliminary CLT Fire Testing Report. FPInnovations. 2013. https://www.awc.org/pdf/codeofficials/2012/Preliminary-CLT-Fire-Test-Report-FINALJuly2012.pdf

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Peterson St-Laurent, G.P. and Hoberg, G. (2016). Climate change mitigation options in British Columbia’s forests: A primer. Pacific Institute for Climate Solutions, UBC Faculty of Forestry, 1-26. http://carbon.sites.olt.ubc.ca/files/2012/01/Primer_ClimateChange-Mitigation-Options-in-BC_.pdf

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Kirschbaum, Miko U.F. et al. Towards a more complete quantification of the global carbon cycle. Biogeosciences, 16 (3), 831-846. https://bg.copernicus.org/ articles/16/831/2019/

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Micales, J. A., & Skog, K. E. (1997). The decomposition of forest products in landfills.

International Biodeterioration and Biodegradation, 39(2–3), 145–158. https://doi. org/10.1016/S0964-8305(97)83389-6

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Wang, X., Padgett, J. M., Powell, J. S., & Barlaz, M. A. (2013). Decomposition of forest products buried in landfills. Waste Management, 33(11), 2267–2276. https:// doi.org/10.1016/j.wasman.2013.07.009

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