What it is
EPA WARM (Waste Reduction Model) estimates greenhouse gas emissions, energy savings, and economic impacts of different waste management practices for 34 material types. Users input waste quantities and select management scenarios: source reduction, recycling, composting, anaerobic digestion, combustion, and landfilling. WARM calculates total GHG emissions (in MTCO2E) for each scenario, showing the environmental benefit of diverting specific waste streams from landfill.
Why we picked this
WARM is the tool that municipalities and waste professionals use to justify recycling and composting programs to city councils. It provides the hard numbers: how many tonnes of CO2 are avoided by recycling paper versus landfilling it, or by composting food waste versus incinerating it. For household use, WARM shows which materials deliver the most environmental benefit when recycled or composted. The answer is often counterintuitive: recycling aluminum saves more energy per tonne than recycling any other material, while composting food waste prevents more methane than any other diversion strategy.
Key takeaways
- Recycling one tonne of aluminum saves 9 to 10 tonnes of CO2 equivalent, making it the single highest-impact material to recycle by weight.
- Composting food waste prevents 0.5 to 1.0 tonnes of CO2 equivalent per tonne diverted from landfill, primarily by avoiding methane generation.
- Source reduction (not producing the waste in the first place) delivers 2 to 10 times more GHG savings than recycling the same material, confirming 'reduce' as the priority over 'recycle.'