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Reuse and recycle C&D waste for LEED certification to combat waste materials and protect the environment

C&D waste sits in a pile
The construction and demolition industry generates a substantial amount of waste in the form of concrete, soil, lumber, glass, plastic, drywall, and more.

Each year, the construction and demolition (C&D) industry generates a substantial amount of waste in the form of concrete, soil, lumber, glass, plastic, drywall, and more. Processing these materials has already proven to be a challenge for contractors, something that will only be compounded as C&D waste is set to continue to grow to reach 2.2 billion tons globally by 2025, according to a report by Transparency Market Research. 

While the waste produced from new construction is usually clean and uncontaminated, demolition waste is often mixed with other materials which creates numerous challenges when it comes to waste reduction. To combat the large amounts of waste materials and protect the environment, the Leadership in Energy and Environmental Design (LEED) certification was developed to help create buildings that incorporate sustainability into every aspect of their development and construction. And since C&D waste is a part of the construction process, LEED certification must now address how to recycle these materials or add them to the circular economy

To become LEED certified, a project must follow specific criteria that address factors such as carbon, energy, water, waste, transportation, and materials before going through a verification process. Part of this criteria includes having a plan in place for the recovery, reuse, and recycling of the resulting materials.

Reusing waste through proper handling

As more construction sites pop up, they generate more waste. Even if engineers and contractors aren't working toward LEED certification, it's important to make eco-friendly choices about the waste they create. For those looking to earn LEED credits, they must handle their construction and demolition waste thoughtfully. 

The latest rules for LEED certification have more of a focus on earning credit for properly handling C&D waste. This type of credit falls under the Materials and Resources (MR) category. 

Architects pursuing LEED certification for their newest projects can use the rules in the LEED v4.1 in addition to the latest rules that make it easier to earn points. The newest rules focus on reducing the amount of C&D materials sent to landfills and incinerators; the U.S. Green Building Council instead aims to have the materials recovered, reused, or recycled.

Sorting and salvaging materials

Earning LEED credits for C&D materials involves weighing the waste or determining the volume. Regardless of their choice, contractors need to be consistent throughout the project. Before measuring the waste, workers should remove excavated soil and land-clearing debris from the waste. 

Contractors should calculate materials added to the alternative daily cover as waste, not as diversion. They should not include waste-to-energy materials except for wood waste converted into biofuel. International projects that cannot reuse or recycle enough to earn credits can turn to waste-to-energy to divert their C&D materials.

Standards for earning credits

Projects can earn one point toward LEED certification if they can divert 50 percent of the materials and create three material streams for the resulting waste at the end of the project. Another option is to divert 50 percent of the waste to a certified commingled recycling facility and an additional material stream. Commingled recycling facilities sort items, which is why they can satisfy two material streams. 

Project engineers can divert 75 percent of the waste into four material streams to earn two points. If contractors choose to divert 75 percent of the waste to a certified commingled recycled facility, they only need to divert two more streams to earn two points. 

The final option is to earn two points by reducing the total C&D waste material at the site. Contractors must salvage or recycle the debris using waste-minimizing strategies. The standards include the following:

  • Salvaging or recycling a minimum of 75 percent of renovation and demolition waste.
  • Reducing new-construction waste to less than 7.5 pounds per square foot, except at warehouses.
  • Reducing new-construction waste to less than 2.5 pounds per square foot at warehouse projects.

What are waste streams?

Different communities have various waste streams to collect and recycle. In most communities, the streams include paper, cardboard, glass, and plastic. Communities focused on renewable energy also have streams for bio-waste, wood, or textiles. 

More complex waste streams collect electronic, vehicle, and construction waste. These waste streams can be complex because the larger items have more parts that need sorting. The complexity forces small communities moving toward zero waste to turn to third-party service providers.

Each waste stream properly handles the unique items that flow through it. Without proper handling, the waste can cause environmental damage and potential injuries to the employees working at the facilities. Proper handling removes chemicals and toxins so other components can be recycled or reused. 

When contractors create their waste streams, they must ensure that the streams remain pure. This is because the wrong items in a stream could contaminate the dedicated stream. When a stream is contaminated, it becomes devalued, and the effort to help the environment becomes a strain on it instead. 

The circular economy and waste streams

To become LEED certified, construction sites can take steps to reuse their materials. Considering that the construction industry creates significant waste, a plan to recover and reclaim materials should be incorporated into the project. For example, some engineers use excavated earth to make compressed earth blocks and clay plasters. Since excavated earth does not count toward LEED certification, engineers should look for ways to reuse construction materials. 

Plastics also often end up in waste streams, but much of it can be reused or upcycled. For example, some companies reuse plastics from jars and soda bottles to make insulators, removing some of the millions of tons of plastics from waste streams. 

Construction engineers can also turn to eco-friendly, sustainable practices to remove waste from their projects. With so many people moving to cities, engineers are beginning to look toward modular construction to remove the waste and energy used in new construction. 

Overall, reducing waste from construction and demolition can be achieved by using alternative construction ideas. Otherwise, contractors must divert their waste materials into dedicated streams where they can be handled appropriately to reduce landfill and incinerated waste.

Nicolle Portilla is the social media manager for RTS.

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