By Shannon Bergstrom
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 professionals 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 levels, 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 materials — 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 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 percent 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 be reused or recycled/composted.
Using Sustainable Materials
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 agriculture), 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.
In addition to exploring what you’ll build with and where it comes from, it’s also important to pay close attention to how much you need. Ordering excess material for a project can lead to direct waste through it simply sitting on a site, increased energy and transportation waste by shipping unnecessary goods, and financial waste because you’re buying stuff you don’t need. As well as quantity, also plan for variants of any material—don’t get 12ft planks when 10ft will do.
LEED can help with this planning stage through its extensive framework. One such credit designed for this is “Construction and Demolition Waste Management Planning,” which is required for BD+C: New Construction. Additionally, there are five points available for the “Building Life-Cycle Impact Reduction” credit, which is focused around planning, specifically “by reusing existing building resources or demonstrating a reduction in materials use through life-cycle assessment.”
On-Site Waste Management for Sustainable Construction
Once the planning stage is complete and you’re actually on-site, there are many areas for potential waste generation. A first general step is the creation of a designated waste management area with a waste management partner. All waste from a site can be funneled here, where trained operatives are able to follow the waste hierarchy, separating out reusable materials that can go back to the site, recyclable materials that can be sent for processing, and anything that goes to landfill.
However, before anything ends up at the designated waste management area, we should look to the top of our waste reduction hierarchy: reduce. And one way to reduce the wastage of materials is through the improvement of skills. There will always be some slip-ups, of course, but ensuring you work with a skilled and reliable team can mean a reduction in the amount of materials and items being wasted from miscuts, mismeasurement, drops, and more.
Additionally, while you should avoid excess material in your planning stage, there will often be some surplus during construction. Explore the opportunities for returning excess or even waste material to suppliers. Offcuts can sometimes be sent back and resold for use in other projects, while take back services could mean far less usable waste being sent to the landfill.
Finally, packaging can be a real issue, and while many consumers are trying to reduce this type of waste while grocery shopping, the same is not true in the construction industry. Take the time to look for materials and products that come with less packaging — this can help on-site waste and its associated management costs.
Like with the planning stage, you can use the LEED framework to help stay on track. Specifically, there is the two-point credit “Construction and Demolition Waste Management,” which outlines strict measures for diverting waste streams or reducing your total waste.
Waste Management at End-of-life: Demolition & Deconstruction
As mentioned earlier, you should plan for any project’s end-of-life, but it is also worth considering how to reduce waste when you are bringing that end. Around 90 percent of all C&D waste comes from demolition, so reducing it at this point can have a massive impact, whether you’re clearing space for a new construction or just bringing a building down.
To do so, look towards deconstruction rather than demolition. This involves stripping a building to salvage its usable materials. It is especially applicable for wood-framed buildings, those with high-value elements, those that are structurally sound, and those with good bricks but bad mortar.
Deconstruction not only reduces the amount of waste generated at the end of a building’s life but also creates materials that are redirected into new construction projects (either your own or others) to reduce the amount of raw materials needed, bringing us full circle.
Like with the on-site LEED framework, the Construction and Demolition Waste Management credit can help implement the required waste diversion and reuse needed to achieve sustainable construction waste management when bringing down a building.
Construction and demolition waste is a major issue, but it can be tackled by addressing waste points throughout the lifecycle of a building. Planning ahead, good site management, and better demolition techniques through the lens of the waste hierarchy can lead to significant reductions and greener, more sustainable construction.
Shannon Bergstrom is a LEED Green Associate, TRUE waste advisor. She currently works at RTS, a tech-driven waste and recycling management company, as a sustainability operations manager. Shannon consults with clients across industries on sustainable waste practices.