Achieving MRc Construction and Demolition Waste Management in LEED v4.1
Green Building Team on March 28, 2020
Option 1: Diversion
The July 2019 LEED BD+C v4.1 Addenda included positive changes to Option 1: Diversion which adjusted the requirements to make this option more achievable. Project teams can now earn one point using Path 1, by diverting 50% of total construction and demolition material through at least two material streams, rather than three. Two points are earned using Path 3 by diverting 75% of total construction and demolition material through at least three material streams, rather than four. The October 2018 LEED Technical Bulletin outlined how to define a material stream. Remember that a material stream is defined by where the material ends up. For example, wood can be diverted for fuel at a power generation facility, and 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.
New paths 2 and 4 have been added for projects to demonstrate compliance using commingled recycling; however, these paths require the use of an offsite sorting facility certified by the Recycling Certification Institute or approved equivalent. As there are currently no certified recycling facilities in Canada, these new paths are not yet achievable for Canadian projects.
Under LEED v4 and v4.1, commingled recycling can only count as a single material stream unless the project team provides documentation confirming the project specific diversion rates (by material). Note that if the sorting facility provides project specific totals, the materials must be sorted and weighed to determine the weights for each material stream. Visual inspection is not an acceptable method for documenting the diversion rate. Alternatively, the commingled recycling may count as a single material stream using the facility’s average diversion rate, which must be regulated by the local or state authority and must exclude alternative daily cover (ADC). (See the October 2018 LEED Technical Bulletin for more details.)
Option 2: Reduction of total waste material
LEED v4.1 also adjusted the threshold for Option 2 to use more achievable thresholds. All BD+C project types (except Warehouse and Distribution projects) only need to reduce waste generation to less than 36.6 kilograms of waste per square meter, rather than the previous stricter threshold of 12.2 kg/m2. Additionally, this threshold now only includes construction waste; renovation and demolition waste has been separated to a distinct requirement, to divert 75%. Based on the last two years of data collected from recently certified LEED Canada 2009 projects, it is estimated that at least 10% of New Construction projects should be able to achieve the new threshold and over 35% of Core & Shell projects.
Remember, though, when using this option, project teams must provide a narrative to describe strategies in design and construction to prevent or reduce waste from being generated on the jobsite, as well as documentation supporting the total waste per area. Ideas for source reduction can be found in the LEED BD+C v4 Reference Guide under Further Explanation, and include prefabrication, modular design, and designing for standard material lengths.