Many characteristics of timber bamboo make it potentially the most sustainable product for building. First, bamboo’s fast growth rate makes it more renewable than any wood alternative, allowing it to capture and sequester more CO2 per planted area. Second, that same high growth rate makes it substantially more efficient regarding land use needed to provide building products. Third, all bamboo naturally regenerates from the same below ground rhizome (a bamboo’s root) structure after the aboveground portion of the culms has been harvested. Unlike wood forests or plantations, which are harvested every 18-45 years by clear-cutting, timber bamboo is harvested by inter cutting one-quarter to one-third of the mature plants every year and never clear-cut. Fourth, bamboo can grow in many sloped or hillside locations where it will help stabilize the soil and limit erosion. (Source: Quantis LCA Report) And fifth, per comparable area, timber Bamboo generates more oxygen and absorbs more run-off water than wood.
Bamboo grows naturally throughout the tropical and subtropical Western Hemisphere and can grow up to 22 cm per day and reaches its full height of 60’ to 110’ in its first growing season. The culm (pole) walls continue to grow in density until the culm reaches its maximum structural strength between three and four years. (Correal & Arbelaez 2010). The annual yield or rate of growth per acre of Guadua is remarkable. When compared to eucalyptus, a fast-growing structural lumber used in Europe, Guadua is over four times more productive. Even when compared to other timber bamboos, Guadua shows superior yields. The Asian Bamboo Moso used for bamboo veneered flooring is the most heavily exported bamboo in the world. Guadua’s yield per acre is nearly three times that of Moso. “The annual yield of bamboo, in combination with its durable root structure, is its big advantage. Regarding land use, bamboo seems to be one of the promising solutions in the required shift towards renewable source materials.” (Vogtlander, J et al., 2010).
Because timber bamboo is fully grown and harvestable within four to six years in a mature stand, it regenerates far faster than typical lumber used in building framing. Once mature, by harvesting 25% of a plantation or stand every year, timber bamboo has an effective rotation age of four years. In contrast, Douglas fir has a rotation age of 45 years. Over the 45-year period, 2.47 acres (1 hectare) of Douglas fir sequesters 340 MT CO2, while timber bamboo over an equivalent of 45 years sequesters 3400 MT in long term storage. As shown in the figure below, timber bamboo has the potential to yield ten times the merchantable biomass of Douglas fir and thus sequester ten times the CO2. (Quantis, p.32-33)
Land-use is another way to compare the relative sustainability of timber bamboo and wood by normalizing to the amount of land needed per home. The calculation was based on the merchantable volume per hectare per year, and the final amount of wood or bamboo needed in an “average” house. As shown in the figure below, BamCore walls need just 22% of the land area compared to that for a traditional Douglass fir framed walls. This relative land-use efficiency of growing timber bamboo for BamCore wall systems does not include further benefits from floor and roofing system that BamCore has underdevelopment or from the reduction of jobsite waste in a BamCore installation.
Economizing on Land Use – Bamboo is Better
As an example of the large-scale effect of bamboo production, Quantis also considered the hypothetical case where 22% of softwood forests in the US are converted to managed, harvested bamboo forest. If 22% of softwood forests growing timber for building homes were converted to growing bamboo, and the remaining land was left as natural, unharvested forest, there would be an additional carbon benefit of approximately 12,250 kg CO2e/BamCore house.
True sustainability is broader than just fighting climate change. It includes many other types of impact that a product or material can have. Timber bamboo, including Guadua and other species, have a broad range of positive sustainability attributes. The figure below shows carbon sequestration as well as oxygen generation and water retention per area.