An Introduction to the Waste Reduction Model

An Introduction to the Waste Reduction Model

EPA LogoFor waste management professionals, calculating the full environmental impact of waste is a complex task. Not only are there obvious physical factors to be considered—like what type of waste one is dealing with, how much of it there is, and where it’s going—it’s also important to take into account questions like how much energy different waste management techniques consume and how many greenhouse gas (GHG) emissions they generate.

Fortunately, help in answering these questions is available for individuals and organizations involved in solid waste management. An initiative of the Environmental Protection Agency, the Waste Reduction Model (WARM) is a tool that waste planners can use to track and calculate the GHG emissions arising from their waste management practices. Read on for a basic overview of WARM, how it works, and why it matters.

What is WARM?

Available in the form of a downloadable spreadsheet, WARM is essentially a sophisticated calculator. Users input information related to their waste management practices (such as landfilling, recycling, or composting) and the types of waste they handle, and the model tallies up the resulting GHG emissions, expressed as metric tons of carbon dioxide equivalent, metric tons of carbon equivalent, and energy units. This helps waste management professionals get a more detailed picture of the overall impact their practices are having on climate change and the environment, and also provides information on GHG emission reductions that could arise from adopting alternative waste management techniques.

How does WARM work?

WARM’s main purpose is to provide comparative emission results for the treatment of a particular type of waste material in both a baseline and an alternative management scenario. For example, if a waste management company is trying to decide between sending 10 tons of office paper to the landfill and recycling that same amount of paper, it can use WARM to calculate the GHG emissions implications of each strategy. To perform these calculations, WARM relies on the latest data on factors like the carbon content of fuels (used to transport the waste to its treatment facility), the energy required to recycle a designated quantity of the waste in question, and the GHG yield of a typical landfill. These baseline statistics provide an essential basis for comparison with the specific information input by a waste planner using WARM.

The Environmental Protection Agency regularly updates WARM as new data and statistics, as well as new modeling technologies, become available. At present, WARM recognizes 54 different types of waste materials, including aluminum cans, glass, newspaper, mixed plastics, food waste, and yard trimmings. It also offers available information on the emission factors associated with each one.

Who should use WARM?

WARM can be useful to a wide range of organizations and individuals. Its primary purpose is to help decision-makers—whether from waste management companies, municipalities, or other planning or management institutions—make well-informed, data-driven choices about which waste management practices to adopt. However, it’s also a useful tool for anyone interested in the energy and GHG impacts of managing waste materials. State and local governments, small businesses, and students can all benefit from considering the accurate, comparative scenarios that WARM can generate.

What information do people need to use WARM?

landfillThe more precise and detailed the information that a user inputs into WARM, the more accurate and comprehensive the resulting scenarios will be. At minimum, users need to enter information on the quantity of waste in question, broken down by material type; the waste management practice currently used to handle the waste (at present, WARM has data available for recycling, composting, landfilling, anaerobic digestion, or combustion); and the alternative waste management practice to be used for comparison purposes (this can include source reduction, or diminishing the amount of waste generated in the first place).

Beyond these details, national average default data is available for factors like transportation distances and landfill gas recovery efficiency, but if users can enter site-specific information wherever possible, the results will be more accurate. If they have the information available, users can also enter details on things like particular landfill characteristics, specific characteristics of the waste materials (such as whether they were produced from virgin materials or using recycled components), and the location of the regional electricity grid.

Why is WARM important?

Statisticians know that before you can change something effectively, you must first measure it, and this is also true for waste management practices. In order to determine which waste management techniques and solutions offer the highest chance of lowering GHG emissions, reducing the carbon footprint, and helping improve the environment, waste management planners must understand the impact that their current practices have, and thoroughly analyze which alternatives are most suitable for their situation. Accessible and user-friendly, WARM provides this information to anyone who needs it, and can thus help set individuals and organizations alike along the path to effective, sustainable, and environmentally-friendly waste materials management.

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