Basic Information about the Waste Reduction Model
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What is WARM?
WARM is a tool that provides high-level comparative estimates of the potential GHG emissions, energy savings, and economic impacts of materials managed in baseline and alternative materials management practices, including source reduction, recycling, composting, anaerobic digestion, combustion, and landfilling. The model estimates emissions, energy units and economic factors across a wide range of material types commonly found in municipal solid waste and construction and demolition debris in the following categories:
- Metric tons of carbon dioxide equivalent (MTCO2E),
- Energy units (million British Thermal Unit - BTU),
- Labor hours,
- Wages ($), and
- Taxes ($).
WARM is currently available as a downloadable Microsoft Excel spreadsheet.
Potential GHG savings are calculated by comparing the estimated emissions associated with managing materials under an alternative scenario with the estimated emissions associated with the user’s baseline scenario (i.e., current practices), as opposed to simply multiplying the quantity of materials managed by an emission factor. For example, the GHG savings of recycling one (1) short ton (standard U.S. ton) of aluminum cans instead of landfilling them would be calculated as follows:
(1 short ton × -9.13 MTCO2E/short ton) - (1 short ton × 0.02 MTCO2E/short ton) = -9.15 MTCO2E
WARM is periodically updated as new information becomes available and new material types are added. Users may refer to the model history to better understand the differences among various versions of WARM. WARM was last updated in December 2023. WARM was not developed for and should not be used for final site-specific materials management decisions, when other human health and environmental impacts of the different management methods may need to be considered (such as air pollution, water pollution, noise pollution, etc.). WARM is a comparative tool rather than a comprehensive measurement tool. It also should not be used for developing GHG inventories, which need to establish a baseline and measure reductions over time on an annual basis for an entity.
Who Should Use WARM?
WARM provides screening-level comparisons of potential greenhouse gas emissions reductions, energy savings, and economic impacts when considering different materials management practices. Materials management practices include source reduction, recycling, composting, anaerobic digestion, combustion, and landfilling. WARM can be used by individuals and organizations ranging from state and local governments, students, small businesses, and other organizations interested in the comparative potential GHG, energy and economic impacts from materials management scenarios. WARM was not developed for and should not be used for final site-specific materials management decisions, when other human health and environmental impacts of the different management methods may need to be considered (such as air pollution, water pollution, noise pollution, etc.). WARM is a comparative tool rather than a comprehensive measurement tool. It also should not be used for developing GHG inventories, which need to establish a baseline and measure reductions over time on an annual basis for an entity.
What Materials Are in WARM?
WARM now recognizes 61 material types, which are presented in the table below. Their emission, energy and economic factors are available for viewing in units of metric tons of carbon dioxide equivalent (MTCO2E), million BTU, labor hours, wage dollars and tax dollars.
| Material Types Recognized by WARM | ||
|---|---|---|
| Aluminum Cans | Food Waste | Mixed Plastics |
| Aluminum Ingot | Food Waste (meat only) | Mixed Recyclables |
| Asphalt Concrete | Food Waste (non-meat) | Newspaper |
| Asphalt Shingles | Fruits and Vegetables | Office paper |
| Beef | Glass | PET (polyethylene terephthalate) |
| Branches | Grains | Phonebooks |
| Bread | Grass | PLA (polylactic acid) |
| Carpet | Hard-copy Devices | Portable Electronic Devices |
| Clay Bricks | HDPE (high-density polyethylene) | Poultry |
| Concrete | LDPE (low-density polyethylene) | PP (polypropylene) |
| Copper Wire | Leaves | PS (polystyrene) |
| Corrugated Cardboard | LLDPE (linear low-density polyethylene) | PVC (polyvinyl chloride) |
| Cathode Ray Tube (CRT) Displays | Magazines/Third-Class Mail | Steel Cans |
| Dairy Products | Medium Density Fiberboard | Structural Steel |
| Desktop Central Processing Units (CPU)s | Mixed Electronics | Textbooks |
| Dimensional Lumber | Mixed Metals | Tires |
| Drywall | Mixed MSW (municipal solid waste) | Vinyl Flooring |
| Electronic Peripherals | Mixed Organics | Wood Flooring |
| Fiberglass Insulation | Mixed Paper (general) | Yard Trimmings |
| Flat-Panel Displays | Mixed Paper (primarily from offices) | |
| Fly Ash | Mixed Paper (primarily residential) | |