The article, “Will Pure Wooden High-Rise Building Be a Game Changer for Decarbonisation, Obayashi Corporation’s Challenge” by Clark (2023), examines how Obayashi Corporation employs wooden construction to create competitive buildings with a smaller carbon footprint.
The Port Plus Obayashi Yokohama Training Centre uses cross laminated timber (CLT) and laminated veneer lumber (LVL) as key structural elements. Port Plus stands out for its implementation of rigid cross joints, which binds columns and beams using glued in rods (GIR) and a Japanese carpentry technique known as Nuki (Port Plus, n.d.). Nuki involves sliding a pre-cut section of lumber into another section. Another feature of Port Plus is the use of “O Mega Wood” offering fire resistance and earthquake protection comparable to traditional concrete and steel buildings (Obayashi, n.d.). In an earthquake-prone country like Japan, wooden construction can provide as a comparable alternative.
While the article presents a compelling case for wooden construction, it prompts the question of whether wood harvesting for this purpose truly achieves meaningful carbon reduction.
The first point to consider is the environmental impact of wood harvesting. Global wood harvests are projected to contribute 3.5 to 4.2 billion metric tons of greenhouse gases to the atmosphere annually in the foreseeable future, amounting to approximately 10% of recent annual carbon dioxide emissions (World Resources Institute, 2023). This draws attention to the crucial function of trees within the forestry ecosystem, where they absorb carbon dioxide through the process of photosynthesis. When trees are removed, the disruption extends beyond just carbon dioxide removal. Nutrients flow become disrupted, affecting surrounding trees, soil and forest bed (Dyck & Mees, 1990).
The second point to raise is a critical oversight that emerges from overlooking the inefficiency in wood harvesting. Only a quarter of a harvested tree is deemed suitable to be used as building materials, with the remaining three quarters either buried, burnt or left on its own (Peng et al., 2023). This revelation from a study by Peng and his team prompts the need for a thorough examination of wood sustainability where a significant portion of wood harvested remains non-reusable. While the current scale of using wood as a building material is relatively small, the consequences could be detrimental if wood were to replace conventional building materials as the norm (Roston, 2023). It is imperative that more comparison studies be conducted in order to determine whether the use of wood in this manner could still result in lower carbon emissions overall compared to using concrete and steel.
One such study by Ramage et al. (2017), they shared two key areas for future research on wood which are understanding the logistics processes behind timber trade and formulating appropriate policies, both are crucial in assessing the impact of wood harvesting. Firstly, analysing the carbon footprint across the entire supply chain of timber trade from logging, processing to transportation and distribution will provide researchers with a comprehensive understanding of the environmental impact of using wood as building material. Secondly, this new knowledge can then guide policymakers in setting international and regional forest strategies to address the challenges posed by forest harvesting. According to Ramage et al. (2017), effective policy measures include implementing stringent regulations to control wood usage which help strike a balance between wood demand and the time needed for trees to grow. Therefore, conducting studies in these areas will facilitate the search for answers to understand and mitigate the environmental impact of wooden construction.
While the debate of wood environmental friendliness persists, it is undeniably a superior alternative to concrete and steel in terms of carbon emissions produced. In a study by Buchanan & Honey (1994), they conducted a comparison of carbon emissions generated from the various building materials. Wood building materials such as treated timber and glue laminated timber emitted negative carbon emissions overall as carbon is stored in timber products whereas, building materials such as structural steel and reinforced concrete produced 8,117 and 182 kilogram per cubic metric of carbon emissions respectively. Unlike wood, concrete production involves limestone calcination, a process which emits carbon dioxide as a byproduct, contributing to high emission levels (Gustavsson & Sathre, 2006). One positive example illustrating the viability of transitioning from concrete and steel to wooden construction can be observed in New Zealand. The increasing trend towards wooden construction in residential and commercial buildings in New Zealand could result in 20% reduction in carbon emissions. Furthermore, this shift could contribute to a 1.8% decrease in New Zealand's total atmospheric carbon level (Buchanan & Levine, 1999). Hence, such findings present a strong case for wood as building material, aligning with global efforts toward decarbonisation.
In summary, while wood offers significantly lower carbon emission levels compared to concrete and steel, critical considerations regarding efficiency, sustainability, and global wood harvesting impact must be addressed first. Achieving sustainable construction and true carbon reductions necessitates the need for further comprehensive studies and effective policies.
Reference List:
Buchanan, A.H., & Honey, B.G. (1994). Energy and carbon dioxide implications of building construction. Energy and Buildings, 20(3), 205-217. Energy and carbon dioxide implications of building construction - ScienceDirect
Buchanan, A.H., & Levine, S.B. (1999). Wood-based building materials and atmospheric carbon emissions. Environmental Science & Policy, 2(6), 427-437. Wood-based building materials and atmospheric carbon emissions - ScienceDirect
Clarke, A. (2023, November 6). Will pure wooden high-rise buildings be a game changer for decarbonization, obayashi corporation's challenge. Bloomberg. Will pure wooden skyscrapers be a game changer for decarbonization, Obayashi's challenge - Bloomberg
Dyck, W.J., & Mees, C.A. (1990). Nutritional consequences of intensive forest harvesting on site productivity. Biomass, 22 (1-4), 171-186. Nutritional consequences of intensive forest harvesting on site productivity - ScienceDirect
Gustavsson, L., & Sathre, R. (2006). Variability in energy and carbon dioxide balances of wood and concrete building materials. Building and Environment, 41(7), 940-951. Variability in energy and carbon dioxide balances of wood and concrete building materials - ScienceDirect
Obayashi Corporation. (n.d.). Low-cost, long-span fire-resistant wood construction technology: O･Mega Wood (FR). Low-Cost, Long-Span Fire-Resistant Wood Construction Technology: O･Mega Wood (FR) | Appendix | OBAYASHI CHRONICLE 130 English
Port Plus. (n.d.). OY Project. oyproject.com
Peng, L., Searchinger, T.D., Zionts, J., & Waite, R. (2023). The carbon costs of global wood harvests. Nature. The carbon costs of global wood harvests | Nature
Ramage, M.H., Burridge, H., Busse-Wicher, M., Fereday, G., Reynolds, T., Shah, D.U., Wu, G., Yu, Li., Fleming, P., Densley-Tingley, Danielle., Allwood, J., Dupree, P., Linden, P.F., & Scherman, Oren. (2017). The wood from the trees: The use of timber in construction. Renewable and Sustainable Energy Reviews, 68, 333-359. The wood from the trees: The use of timber in construction - ScienceDirect.
Roston, E. (2023, January 27) Just how climate-friendly are timber buildings? It's complicated. Portland Press Herald. Just how climate-friendly are timber buildings? It’s complicated. (pressherald.com)
Searchinger, T.D., Peng, L., Waite, R., & Zionts, J. (2023). Harvesting wood has overlooked carbon costs. World Resources Institute. Harvesting Wood Has Overlooked Carbon Costs | World Resources Institute (wri.org)
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