It’s Easy Being Green: What Do Cow Dung, Car Tires, and Denim Have in Common?
The building industry could use some sustainable alternatives when it comes to raw materials: It consumes a whopping 3 billion tons worldwide each year. That’s where green building materials come in. They help reduce the environmental impacts attached to everything from extraction and transportation to the installation and disposal of materials.
Materials must meet at least one of the following criteria to be considered green: recycled, renewable, local, durable, low or nontoxic with minimal chemical emissions, and have a resource efficient manufacturing process. In effect, green materials must significantly reduce or eliminate maintenance costs over the building’s lifespan, and should allow for greater design flexibility.
These materials also tend to be a little unusual. Here’s a list of some of the most unexpected, interesting, and just bizarre green home building materials available today.
Methane from decomposing cow dung accounts for 16 percent of global greenhouse gas emissions according to the International Energy Agency. That’s about five tons of CO2 per cow per year. Cow dung that covers land also poses a substantial health risk to local citizens.
But now all that waste can be converted into hygienic homes. EcoFaeBrick, created in 2009 to tackle Indonesia’s massive cow dung overload, processes cattle waste into building bricks that are 20 percent lighter yet 20 percent more compact than clay bricks. Traditional clay excavation also damages cultivatable land on a massive scale, but using dung instead of clay preserves acres of productive land so that local farmers can keep farming without all the pesky waste in the way.
EcoFaeBrick established a partnership with the Indonesian farmers to use the dung on their land and provide them with an additional income of 53 percent. It also uses the methane biogas produced by the dung in the combustion process instead of firewood. This reduces 1,692 tons of CO2 per year and provides a lower production cost than clay bricks, which cost, look, and smell the same as the dung ones.
Concrete isn’t usually considered a green product because of the enormous amount of energy required in its production. But Litracon™, invented by Hungarian architect Áron Losonczi in 2001, is a new building material that mixes small optical fibers with concrete to create light-transmitting solid blocks. Litracon is produced as prefabricated blocks or panels, and it reduces both indoor lighting costs and window-based heat loss.
The fibers, which account for roughly 4 percent of the material, function without any light loss for a thickness of up to 20 meters. And they have no negative effect on the load-bearing compressive strength capabilities of the concrete.
Litracon, unsurprisingly, is expensive. It costs about $1,040 per square yard compared with $70 per cubic yard for regular concrete. But Litracon walls lead to less electricity use because of natural light.
Two hundred eighty-one million scrap tires were made in 2001, weighing about 5.68 million tons according to the Rubber Manufacturers Association. But automobile tires are more than just a leaky, oily staple of every scrap yard. They can serve as sturdy walls, evidenced by the cultish popularity of earthships first created by Michael Reynolds in the 1970s.
Naked tires found at used car dealerships and junkyards are rammed with dirt, concrete, or loose gravel to make rubber bricks, and then laid in an overlapping pattern before they are covered with adobe-style plaster. Because they are sealed, they don’t have that tire smell, and years of exposure to oxygen on the road causes oxidation, which means they do not outgas. Recycling used tires into walls is a labor-intensive and time-consuming process, but it’s a sturdy alternative to more expensive construction where you actually have to pay for your materials.
UltraTouch insulation, developed by Bonded Logic, is primarily comprised of post-industrial recycled natural denim. This means all the scraps left on the factory floor after your favorite jeans are manufactured get cleaned, cut into strips, and covered with a low-toxic boron-based fire retardant that prevents fungus and mold growth and keeps chewing critters away. Sticking 100 percent recyclable UltraTouch into your walls diverts approximately 300 tons of landfill waste each month. And you can breathe easy since UltraTouch has no warning labels and doesn’t use formaldehyde in its construction.
UltraTouch is on average 15 percent more expensive than fiberglass to install, but it insulates just as well if not better, with superior acoustics, and is safe to the touch.
The United States burns or destroys 200 million tons of agricultural “waste straw” every year. Waste-straw-filled walls, however, provide strong, lasting insulation. The bales are compressed into blocks and bound with polypropylene string to serve as nontoxic infill wall material or load-bearing supports that are just as (if not more so) fire safe than a conventional wall.
This renewable resource is available at many local markets, which reduces transportation and production costs associated with traditional walls. But construction can take a little longer, thereby raising installation costs. Straw also doesn’t do well with water, and plumbing shouldn’t run through these walls to avoid mold. As long as moisture is kept to a minimum, however, straw walls will not decompose.
Glass, crystallized ashes, and other junk
Glass is 100 percent recyclable, and the United States recycles nearly 13 million glass bottles daily. ECO™ by Cosentino has developed countertops from salvaged mirrors, bottle and window glass, porcelain toilets, and industrial furnace residuals from factories in the form of crystallized ashes. Production reuses roughly 60 million glass bottles annually so that new resources are not mined and wasted.
The countertops are composed of 75 percent recycled content that would have ended up in an industrial landfill, mixed with 25 percent natural material, including stone scraps from mountains and quarries. The mixture is bonded together with an environmentally sound 22 percent corn oil resin. The company also uses 94 percent recycled water in production, and the durable countertops do not cost more than your average stone.
These green materials may be a little unconventional, but they’re giving the construction industry some needed sustainability while in many cases working just as effectively as their conventional, raw brethren. So look for that old mirror, car tire, or pair of jeans coming soon to a building near you.