Hi All, do you know which information model in TRACI the carbon impact of construction waste management and diversion factors in? I believe the hauling is captured in A5 but what about the recycling or disposal of the materials? Does this require a different tool perhaps using the EPA’s WARM tool?
Thanks!
Hi Kai,
Are you asking about reporting A5 emissions for LEED v5? If so, a new LEED v5 tool for North America will be launching soon. This tool will let you report A5 emissions under the ‘construction site operations’ tab, similar to the existing carbon tools for North America.
How A5 emissions are captured really depends on your calculation method. We offer a few options:
- You can accurately report project-level construction waste numbers if you have those specific quantities. This would include the waste generated, the transport emissions would then be generated based on the weight of the amount of waste, often transported in dump trucks.
- Another option, though not currently in our LEED tool, is to use a waste percentage assigned to materials. This is a common method and is present in about 90% of other tools.
- We also offer A5 construction scenarios, some of which are proprietary and others based on regulatory or certification guidance.
How this looks in e.g. our BREEAM tool (it will likely look similar for our LEED v5 tool):
Inputs:
Outputs:
I’m not very familiar with the EPA WARM tool, but if it provides the necessary quantities, you should be able to include them in your assessment.
I hope this clarifies things! Let me know if you have any other questions.
Hi, I’m asking about LEED v4.1 though that’s interesting about v5 calculations. In the screenshot below, does A5d Construction Site Material Wastage account for the site construction waste management like if we had a 75% recycling rate?
Kai Starn
Senior Sustainability Consultant
203.857.0200 x3240
Steven Winter Associates
Hi Kai,
Thanks for the update.
Regarding your query, our v4.1 framework doesn’t mandate reporting on A5, so we haven’t included these emissions. Globally, the most prevalent methodology is to account for all waste-related emissions within the A5 category, covering wastage, transport, recycling and disposal.
In the example of my screenshots, A5d and A5d-leg2 address waste transportation. We calculate this based on the wastage percentage (e.g., 2% of ready-mix concrete waste that’s downcycled to aggregate), with the recycling process itself falling under A5e.
Presently, we assume 100% of construction site waste follows a single end-of-life process (e.g., all concrete is downcycled). While you can define separate end-of-life processes (C1-C4) for your included construction materials, this level of granularity isn’t yet common for A5.
Is this an area you’re looking to optimize for your clients, perhaps by tracking more specific end-of-life pathways for A5 waste? We’re very interested to hear your insights on this.
Thanks Steven! I work mainly with LEED projects, with over 30 certified to date, and projects often target higher rates of construction waste diversion (for our area) up to 90%+ recycling of construction waste. I guess I’m curious what the impacts of diverting from the landfill are compared to typical waste disposal <50% diversion. Even a rule of thumb to use for consulting would be useful as projects aim to decarbonize, e.g., every pound of steel/concrete/drywall/insulation diverted from the landfill and recycled avoids 100 kg/CO2e. I’m sure it gets complex because we’re using more energy to recycle it, but avoiding virgin material impacts.
Hi Kai,
Thanks for elaborating. You’re right, understanding the avoided impact of recycling is crucial. While recycling processes do require energy, the consensus is that the benefits of avoiding virgin material production and landfill emissions significantly outweigh those energy costs.
While we don’t have our own “rules of thumb,” I’ve pulled some indicative ranges from the EPA WARM tool that might be helpful for your consulting:
- Steel: Very high savings (e.g., 1.5-2.5 tCO2e avoided per tonne)
- Concrete: Moderate savings, mainly from avoiding virgin aggregate (e.g., 0.01-0.05 tCO2e avoided per tonne)
- Drywall: Good savings, partly due to avoided landfill methane (e.g., 0.05-0.15 tCO2e avoided per tonne)
- Insulation (depends on the type): High savings (e.g., 1.0-2.0 tCO2e avoided per tonne)
Keep in mind, these are general guidelines. For precise figures, it’s best to use the EPA WARM tool directly, as it accounts for various factors. You can access the Excel version here: https://www.epa.gov/system/files/documents/2023-12/warm_v16.xls.
You can also calculate these comparative impacts directly in One Click LCA, which requires a bit of work, though:
- Input Waste Quantity: Enter the total quantity of material that would become waste (e.g., 1000 kg).
- Compare End-of-Life Scenarios: Duplicate this entry. For one, set the end-of-life process to landfill. For the other, set it to recycling.
- Analyze C3/C4 Emissions: Compare the emissions for the C3 (waste processing) and C4 (disposal) stages. For example, 1000 kg of concrete:
- Downcycling to aggregates: ~0.35 kg CO2e
- Disposing to landfill: ~2.6 kg CO2e
- For a basic RMC the material distribution would be similar to the below:
The emissions we’d save from recycling concrete are primarily related to the aggregates, which account for about 5% of a ready-mix concrete’s emissions. This is why the EPA tool shows moderate savings for concrete recycling.
You might find that for some materials, the emissions from the recycling process itself are ‘technically’ higher than landfilling in a direct C3/C4 comparison due to energy use. However, the overarching benefit comes from avoiding virgin material production. For materials like steel and insulation, the positive impact of recycling is much more significant, as I’m sure you’re well aware.
Hope this helps!
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