Roughly a quarter of this C&D waste was sent to landfills, which takes up valuable space as well as allowing for the possibility of environmental contamination. Moreover, a linear approach to construction materials (take-make-dispose) results in more raw materials having to be extracted, processed, and transported – representing a significant environmental and economic cost.
Sustainable management of C&D waste negates these negative impacts, leading to a reduction in the amount sent to landfill, the preservation of natural resources, a lower carbon footprint, and potentially considerable cost benefits. Setting out on the journey to sustainable waste management can seem daunting at first, but there are guidelines and frameworks to help steer construction professionals in the right direction. Of the frameworks out there, LEED is the most widely used and well recognized.
- Building Design and Construction (BD+C)
- Interior Design and Construction
- Operations and Maintenance (O+M)
- Neighborhood Development
When looking for more sustainable C&D waste management, the focus is going to be on the first of these categories, BD+C. Within each category, there are mandatory credits and optional credits. Optional credits are worth varying numbers of points, which a project pursues for the level of LEED certification desired:
- Platinum: 80+ points earned
- Gold: 60-79 points earned
- Silver: 50-59 points earned
- LEED Certified: 40-49 points earned
There are two relevant LEED credits to help guide construction projects towards sustainable C&D waste management. The first is Construction and Demolition Waste Management Planning, a prerequisite (aka mandatory) credit for BD+C: New Construction. The second, Construction and Demolition Waste Management, is worth a potential two points and involves actually implementing the plans put forth in the first credit to reduce the amount of construction and demolition waste sent to landfills and incineration facilities through prevention (reuse and reduction) and diversion (recovery and recycling), following the waste hierarchy.
Early-stage planning is the best way to reduce, beginning with the overarching design of a project. Construction professionals should try to use standard sizes and quantities of materials to avoid offcuts and excess waste. Further, these materials should be delivered as and when they are needed to avoid them being stored on-site. This will also reduce the need for heavy packaging, which while often an oversight, does contribute to the overall waste output of a site. Effectively training staff and the use of skilled workers can also have a significant impact on C&D waste, since there will be fewer errors and less waste resulting from them.
The types of materials a project uses should also be considered. Many products and materials can be sourced used or from previously recycled waste. This reuse of materials and products again helps reduce the natural resources that must be extracted. Sometimes, this reuse can actually happen on-site, especially in the case of buildings that must be demolished before a new one is erected.
This process is called deconstruction, which involves taking a building apart rather than simply knocking it down. Through this process, any number of useful materials can be reused, from plaster moldings to bricks. That said, any construction site is likely to have waste materials that can be reused, such as wood offcuts being utilized before cutting into fresh timber.
The average life of a building is far lower than most would expect, with a study of UK residential buildings finding 46 percent of those demolished were only 11 to 32 years old, and a study of office buildings in Japan finding a typical life span of just 23 to 41 years. Therefore, it is imperative to not only consider where materials are coming from but also where they will go – how materials can be used once a construction project comes to the end of its life should inform the choices a construction professional makes.
More than 74 percent of C&D waste is successfully diverted from landfills, with the vast majority of this (52 percent) going to aggregates. The next largest diversion (22 percent) is to manufactured products. This can include common C&D waste such as metals, which can be turned into numerous products; wood, which can be chipped for landscaping or pulped for paper; and plasterboard, which can have the gypsum recovered. There is also some level of energy recovery from waste such as wood, which can be sent to incinerators that are used to generate power. This is the least desirable option before simple disposal of waste in a landfill, but all paths should be considered for the most comprehensive waste management plan.
Through the use of frameworks such as LEED, and the careful consideration of the waste hierarchy, the sustainable management of construction waste is possible. This will reduce the negative environmental impact of a construction project as well as potentially providing short- and long-term economic benefits for both contractors and the industry as a whole.
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. Bergstrom consults with clients across industries on sustainable waste practices.