C+S December 2020 Vol. 6 Issue 12 (web)

Construction and demolition (C&D) waste is a major concern, with 569 million tons generated in the United States in 2017 alone. That is more than twice the amount of municipal solid waste generated in the same period, making it an issue that goes far beyond just the construction industry. That said, there are various ways to reduce and divert C&D waste when considering a project’s full lifecycle. To do so, it’s best to examine each stage — planning, construction, and demolition — through the lens of the waste hierarchy: Reduce, Reuse, Recycle, Energy Recovery, Disposal. Doing so alone can be a daunting task, so most construction profession- als opt to use a green building framework for their sustainable waste management. One of the most recognized and widely used is LEED, or Leadership in Energy and Environmental Design, which employs a series of required and optional credits to keep projects sustainable. LEED is applicable to all kinds of construction projects and grouped into five main categories: Building Design and Construction (BD+C), Interior Design and Construction, Operations and Maintenance (O+M), Neighborhood Development, and Homes. Within these categories, projects can earn credits in five main areas: sustainable sites, water efficiency, energy and atmosphere, materials and resources, and indoor environmental quality. Earning non-required credits gives a project points, and these points are tallied to award a LEED Certification. There are four possible lev- els, ranging from LEED Certified (40 and 49 points) to Platinum (80 plus points). Planning Ahead for Sustainable Waste Management Making a construction project more sustainable starts before you’ve even broken ground, with planning being arguably the most important stage in going green. When looking at waste, the focus is on materi- als — what you use, how much, where it comes from, and what can be done end-of-life. Some of the most common materials are potentially the worst choice when looking at the full lifecycle of a building. Concrete, for example, is by far the most widely used construction material in the world, but it has a heavy carbon footprint, with cement accounting for roughly 8% of global CO2 emissions. To make matters worse, it's no better from a waste perspective, with concrete unable to be reused in any meaningful way. It can be recycled LEED, Sustainable Waste Management and Green Construction By Shannon Bergstrom

into products such as aggregates, but much still ends up in landfill, and if looked at through our hierarchy, a reusable product, such as bricks, would be a better choice. Bricks still embody significant emissions but can be reclaimed and reused over many generations. Thinking about end-of-life material reuse also involves thinking about tearing a construction down before you’ve even put it up, which can seem very strange. However, considering how little time many builds stay standing, it’s imperative for any project looking towards more sustainable construction waste management. For example, one study of U.K. residential buildings found that 46 per- cent of those demolished were only 11-32 years old, while a study of office buildings in Japan found the average lifespan to be between 23 and 41 years. When buildings are knocked down in less than a single generation, we have to consider how resources can be reused. Knowing a building may come down in merely a matter of years also means you need to question the source of your materials. Ideally, reusing materials from demolished buildings should go hand-in-hand with the use of less toxic and more sustainable alternatives that we will go into later. This reduces the amount of raw material extracted, processed, and shipped as well as bringing down C&D waste across the entire industry through the use of natural materials that can either If salvaged materials aren’t right for your project, then perhaps consider low-waste alternatives. Instead of concrete, look into the possibility of using hempcrete, a composite of hemp hurds (shives) and lime, sand, or pozzolans, for non-load bearing sections of a building. This material actively reduces waste in other sectors (namely agricul- ture), absorbs CO2 whilst being grown, and at the end of its life is non- toxic. Similarly, some construction materials can’t be easily salvaged and reused, such as fiberglass insulation. Unfortunately, this insulation also can’t be recycled and can lead to build-ups of toxins in landfills, which can then leach into the ground. In situations like this, the best way to avoid a waste disaster is again planning for alternatives such as wool, hemp, or soy-based foams. be reused or recycled/composted. Using Sustainable Materials


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