Geek in the Garden: Understanding the nuances of sustainable wood
By Dani J. Winston
Using sustainable materials in a landscape results in a long-term decrease of energy consumption, conserves water, and serves to bolster ecological function by reducing environmental strain. This ultimately contributes to increased environmental services, and healthier, enduring landscapes.
In Designing the Sustainable Site, Heather Venhaus describes a series of benefits supported by sustainable sites. They include ecosystem services, such as regulating temperature and precipitation, sequestering greenhouse gasses, cleansing air and water, providing habitat, maintaining soil health and fertility, retaining and storing fresh water, controlling erosion, and mitigating natural hazards such as flooding, wildfire, and drought. Sustainable sites may also provide social benefits, such as providing recreation, producing food and other raw materials such as timber, medicine, and fuel, providing inspiration and cultural enhancement, and enhancing opportunities for mental respite.
Many factors must be considered when deciding if a material is sustainable. At the minimum, it needs to be long lasting and non-toxic, and created and transported with minimal energy. The material’s entire lifecycle must be considered, from the resources used in production, to the cost of energy and amount of maintenance required, as well as the options for eventually reusing, recycling or discarding. Additionally, consider if a material could improve site health, help repair damaged and disturbed sites, or manage the flow of water.
It is not always evident which products are the most sustainable options for a project and it is important to weigh all the above criteria on a case-by-case basis.
When wood is produced through well-managed, thoughtful, sustainable practices, it could potentially bolster all the aforementioned criteria.
As an example, wood is one of the primary materials in construction and each of these factors must be considered during the decision making process. There are no perfect solutions, but research and planning can help identify the best option.
In the case of wood, there are a number of products types and certifications to consider. The two major certifications for wood are FSC and SFI. FSC is the Forest Stewardship council. FSC’s objectives seek to protect at risk ecosystems, honor native cultures and economies, avert illegal logging, curtail clear cutting and pesticide use and monitor “the chain of custody” in order to ensure that the wood product purchased has actually met all the above criteria.
SFI is the Sustainable Forestry Initiative. SFI’s criteria have become more stringent in recent years and basically mirror those of FSC. Nevertheless, SFI only certifies harvesting operations in the United States and Canada. For wood products sourced outside North America, SFI relies on foreign governments to set the benchmark. Even though SFI benchmarks have become more stringent in recent years, SFI certification practices continue to be less transparent than those of FSC. Hence, it is important to research the sourcing practices of foreign nations before choosing a product.
While certifications are a good starting point, it is important to consider the entire range of relevant factors when trying to determine the most sustainable wood option. For example, it would be better to choose wood derived from locally recycled street trees rather than a certified wood product that was cut and milled in a different state or country. Though the local source might not carry the FSC or SFI certification, the processes and practices related to its production are easier to verify. The energy and resources consumed in transport of a local product are much lower than a product harvested and milled elsewhere.
Thermally treated wood is quickly becoming a viable alternative to exotic hardwoods. Viewed through the lens of sustainability, the choice between thermally treated wood and exotic hardwoods seems obvious. Thermally treated wood is a domestic product that is both durable, beautiful and easier to work with then exotic hardwoods. Surprisingly, thermally treated wood, though sustainably harvested in the United States, is often shipped to Eastern Europe for the thermal process and then shipped back to the U.S., wasting energy and creating pollution through the shipping process. As demand for thermally treated wood increases, it is likely that more domestic processing facilities will be constructed, eventually yielding a viable alternative to exotic hardwoods.
Composite materials are another option fraught with contradiction. Composites are primarily composed of recycled plastics and mill waste, are highly durable, and require minimal maintenance. Unfortunately, there is a downside to most composites. At the end of their lifecycle most readily available composites fall short because in the process of creating a product made from both plastic (which is recyclable), and wood waste (which is compostable), the resulting combination is a product that is neither recyclable nor compostable.
There has been a lot of interest in composite materials lately, and we’re looking forward to seeing where the research and development takes us.
Here are a few products we’ll be keeping an eye on:
Modified wood resources:
Wood certification resources:
Designing The Sustainable Site- Heather Venhaus
Sustainable Landscape Construction-J. William Thompson and Kim Sorvig
Beronio Lumber, San Francisco
Truit and White, Berkeley