Sustainable building owes a lot to good design and taking advantage of the natural resources available at the site, but it also comes down to a “green” choice of materials. The availability of sustainable materials is continually on the rise, with new innovations creating and sourcing materials that aren’t detrimental to the environment and are designed to enhance the energy efficiency of buildings.
While some sustainable materials may require greater up front costs, they bring with them long-term savings due to reduced energy and transportation costs, as well as being beneficial for the environment in the long term.
Recycled and Reused Building Materials
Recycled materials are sustainable because they don’t require the destruction of virgin resources and use less energy and chemicals in their production. Recycled plastic that is ground up to create a concrete-like building material is just one example, utilizing what would otherwise be a waste product clogging up landfill.
When considering recycled materials for building, it’s important to take into account their physical properties, such as strength and stiffness and whether their performance can live up to the structure’s demands. Suppliers of recycled materials should have this information readily available, allowing you to make decisions about your design based on the material’s properties.
Reused materials, such as reclaimed timber, can be even more sustainable, as they require far less manufacturing that recycled building materials. In some cases, buildings can also be designed for easy disassembly, allowing the materials to be reused again in the future for other purposes.
Sustainably Harvested and Rapidly Renewable Materials
When it comes to timber, sustainably harvested or rapidly renewable materials are the most sustainable option. They allow forests to regenerate over time and ensure their resources aren’t entirely depleted or the surrounding ecosystem damaged when the timber is harvested.
The Forest Stewardship Council (FSC) is an international, non-profit organization that promotes the responsible management of the world’s forests by providing sustainable forestry certification. They identify wood products that have been grown or harvested sustainably, allowing builders to make informed decisions. Keep in mind that some tropical hardwoods grow at such a slow rate and within fragile ecosystems that their sustainability as a building material is controversial and extra care should be taken when sourcing them.
On the other end of the spectrum are materials such as bamboo that grow at such a rapid rate that they can be harvested frequently without being detrimental to the plant’s survival. Bamboo is lightweight and has a high tensile strength that makes it ideal for structural elements or interior finishings and furnishings. It can provide a useful alternative to concrete and reinforcement steel in disaster relief shelters and has been used for centuries in housing across Asia.
Cork trees are another example of a rapidly renewable material, with the layers of its bark harvested, rather than the entire tree being cut down. It is naturally fire retardant and has elastic properties that make it ideal for flooring, insulation, wall coverings and countertops.
Non-toxic Building Materials
Sustainable materials in building construction should also be non-toxic, meaning they don’t have a detrimental impact on the indoor air quality or carry a toxicity risk to construction and manufacturing workers. Volatile Organic Compounds (VOCs) that are present as fire retardants, adhesives or refrigerant gases can cause toxicity or leach toxins into the groundwater during heavy rains. Substances to avoid include asbestos, mercury, lead, chlorofluorocarbons and wood treatments with creosote, arsenic or pentachlorophenol.
Locally Sourced Materials
The transportation of building materials long distances can also have a detrimental impact on the environment, so supporting local manufacturers and economies is preferable wherever possible. The impact of transportation is usually less than that of the resource extraction emissions to create the materials, so it’s important to weigh up how they are produced and where they are coming from when making decisions.
Sustainable Materials to Look Out For
The good news for those wanting to build sustainably is that new sustainable materials are constantly being created, while long-established building techniques are seeing a new lease on life as part of the “green” building movement.
Straw bale construction is one such example, having been used to construct dwellings for centuries and providing a high level of insulation. Straw bales are a natural, rapidly renewable and locally-sourced alternative to replace the need for energy-intensive concrete, wood, gypsum or fiberglass.
Rammed earth construction is another ancient building technique that is seeing a modern resurgence, utilizing dirt that is tamped down tightly into wooden forms. It takes advantage of locally sourced earth to create a highly durable structure, with rammed earth homes that were built hundreds of years ago still standing today.
More recent sustainable building innovations include HempCrete, a concrete-like material that is created from the woody inner fibers of the hemp plant bound with lime. HempCrete is made from a rapidly renewable resource to create a material that is strong and super lightweight, helping to reduce the energy requirements of transport. AshCrete is another innovative concrete alternative that utilizes fly ash, a by-product from burning coal, to replace the energy-intensive manufactured components of concrete.
TimberCrete is made using sawdust and concrete mixed together, creating a lighter material when compared to regular concrete to help reduce transportation emissions. Sawdust is otherwise considered a waste product, but in this application, it can replace some of the energy-intensive materials usually used to make concrete. It can also be formed into a whole range of different shapes, including bricks, blocks and pavers, resulting in widespread application.
Ferrock also uses recycled materials to create a concrete-like building material, this time using steel dust that is a waste product from the steel industry. Ferrock has the unique property of actually being able to absorb carbon dioxide as it dries and hardens, making it carbon neutral, while being stronger than regular concrete.
One of the most unique sustainable products currently being researched as a building material is mycelium, which uses the root structure of fungi. It can be encouraged to grow around ground up straw to create a durable composite material or molded into forms and air-dried into strong and lightweight bricks.