Construction and Demolition Waste Management
Green Building Team on October 28, 2018
Under LEED v4 for both the Building Design and Construction (BD+C) and Interior Design and Construction (ID+C) rating systems, the Materials and Resources (MR) credit Construction and Demolition Waste Management has evolved to recognize stronger material diversion. Under Option 1, project teams must not only divert a minimum amount construction and demolition waste (50% for Path 1, 75% for Path 2), they are also required to divert at least three material streams for Path 1 or four materials streams for Path 2. But, what is a material stream?
The LEED v4 BD+C Reference Guide defines a material stream as “a flow of materials coming from a job site into markets for building materials”. Ultimately, a material stream is defined by where the material ends up. In the simplest example, a single material would be diverted in a singular manner; therefore it would be considered a single stream. The reality is that any given material can be diverted many different ways, creating multiple streams. For example, wood can be diverted for fuel at a power generation facility, and also diverted for reuse by a building supply store; both count as separate material streams if tracked separately. Conversely, multiple materials can be diverted in a singular manner, creating a single stream. For example, collecting asphalt, concrete and masonry which is crushed together for fill or aggregate is considered a single stream: on-site waste diversion.
Looking for additional material streams? Consider these waste diversion tactics: deconstructed materials for reuse markets; reuse of deconstructed materials on-site; and manufacturer take back programs, all of which contribute as material streams if tracked separately for your project.
A common method of construction and demolition waste management is commingling materials, with off-site sorting. Commingled waste sent to a mixed waste recycling facility counts as a single material stream regardless of the number of different materials included. However, if the recycling facility can track and document project specific material diversion measured by weight or volume, they may contribute as multiple material streams. It is critical that the documents are project specific and measured by weight or volume, and are consistent throughout. A key change from the previous versions of LEED is that visual inspections are no longer acceptable. Documenting project specific diversion rates for comingled waste may be done through itemized haul tickets or letters from the sorting facility that confirm the process for determining individual material weights. The documentation must be clear that the sorted materials have been separately weighed or measured, not estimated through visual inspection.
Alternatively, commingled waste may contribute by providing the recycling facility’s average annual diversion rates, if they are regulated by local or provincial authority. If using the facility’s annual diversion rate, project teams must provide information about how the facility handles the waste, in addition to confirmation of the facility’s annual diversion rate. Note that projects which only use comingled waste sent to one facility, and use that facility’s annual diversion rate, will only achieve one material stream, and therefore not meet the minimum credit requirements of three material streams.
Documenting overall project diversion rates for the purposes of this credit must include all waste diverted and all waste sent to the landfill. If the project team used more than one waste hauler, enter all of the information into one single document, such as the LEED v4 MR Construction and Demolition Waste Calculator.
So, what’s the best strategy to achieve MRc Construction and Demolition Waste Management? Source separation is the most effective means of achieving high diversion rates and multiple materials streams, as each material type is considered a different material stream.