Construction is a waste-heavy industry. In fact, as much as 30% of all landfill content in the U.S. is composed of construction materials, according to NASA. Each and every year, 500 million tons of building materials, often loaded with toxins, find their way into landfills and incinerators.

We’ve talked about green construction, and the push to create buildings more sustainably through reduced C02 emissions, increased energy efficiency and smarter use of water. But some companies are taking it a step further, working to reduce waste at every step, from the building process itself to demolition, re-using construction materials and even creating new kinds of recycled building materials from some unlikely sources.

One way to reduce waste in construction is building them with eventual disassembly in mind, enabling more materials to be salvaged and reused, rather than creating a pile of unusable rubble that ends up in the waste stream. This creates opportunities early in the design process to adapt used building materials for use in future projects. To that end, the Environmental Protection Agency recommends steps like developing a disassembly plan from the outset, using durable materials worth recovering later (like high-quality, strong wood), using mechanical fasteners like bolts, screws and nails (instead of sealants and adhesives), and minimizing the number of different material types used to increase how much can be recovered.

Food waste is a real problem in the U.S., and some engineering firms are turning to food waste as a source of building materials made from sustainable materials. According to GreenMatters, half of all food produced globally ends up in the trash, making this wasted resource a widely available source for repurposing. According to engineering firm Arup’s report, "The Urban Bio Loop," future buildings could be made from materials including potatoes, pineapples, corn, oranges and mushrooms.

In order for the construction industry to play a role in a sustainable future, new methods and models must be developed, including considering new material sources and increasing the prevalence of recycling and building with an eye towards recovery of materials for later reuse.

“The construction industry must reflect this urgency of change–probably more than others. In fact, it is still permeated by a number of detrimental factors such as the use of high impact materials, non-reversible building solutions, low-efficiency processes and manufacturing,” Arup wrote in its report.

It’s not just a far-flung concept, either. The Museum of Modern Art in New York used 10,000 bricks made from mushrooms to build an experimental tower. The bricks were grown by startup Ecovative, which told GreenMatters the bricks can serve as a substitute for particle board or Styrofoam insulation. German company Wood K Plus has been experimenting creating lightweight walls, doors and furniture using a building material made from corn cobs.

The Biocycler is a machine that collects on-site construction waste and uses living organisms (like mushrooms) as a binding agent. The resulting materials are ground up and turned into lightweight but surprisingly strong bricks, which thanks to their bio-organic makeup, serve as formidable heat and sound insulators, according to Archinect News.

But just because a material can be recycled doesn’t automatically make it a good idea. Choosing which materials are incorporated into building materials should be done in a way that ultimately adds value to them by actually improving them, according to Technologist.

A recent seminar held in Copenhagen focused on recycling and reusing resources in construction drove this point home, highlighting the opportunities in recycled building materials but also emphasizing their use should be deliberate. Technical University of Denmark professor Lisbeth M. Ottosen said in her presentation:

“It is important to emphasize that reutilisation is not the same as depositing waste in building materials. We work to transform waste into valuable resources and using the recycled material as components that ultimately make the building materials better and more sustainable”.

Sustainable construction extends beyond how a building operates once completed. Every phase from pre-construction to demolition has room for improvement from an environmental standpoint, and new methods are coming to light all the time.