The U.S. waste and recycling industry works continually to find new ways to extract value from America’s waste, including viewing waste as an energy resource. While valuable energy is regularly captured from landfill gas emissions, or through conversion of waste via incineration or biological processes, our country’s recycling infrastructure also factors into the energy discussion – not in terms of energy produced, but in terms of energy saved by minimizing greenhouse gas (GHG) emissions.

Waste companies, municipalities and other organizations involved in hauling and managing waste typically use one of two methods for accounting for relevant GHG emissions, both for voluntary reporting and to determine energy savings. The first of these is an annual greenhouse gas emissions inventory, which estimates emissions for a given year and helps establish baselines and chart reductions for specific organizations, communities, industries and even countries. They are helpful for identifying large-scale GHG emitters and for compliance with reporting requirements.

However, annual GHG inventories, by nature, do not offer a thorough glimpse at recycling’s impact on an environmental footprint, specifically neglecting emissions associated with end-of-life management of specific materials. A more complete method for assessing environmental impact and emissions savings from recycling is by using lifecycle GHG data as an accounting tool.

Lifecycle Analysis

Lifecycle analysis allows the user to take a complete look at the environmental footprint of different management strategies. Instead of just using the greenhouse gas inventory emission data from a particular industrial sector such as, say, paper manufacturing, to assess the environmental implications of managing those materials, lifecycle analysis gives a much deeper perspective.

For instance, the analysis would begin with the emissions associated with extracting a raw material such as wood, processing it into pulp, manufacturing it into an end-product such as a corrugated box, using it as a product and finally the emissions associated with the end-of-life management of the box such as recycling, composting or disposing, including the option of landfill gas recovery or waste from energy.

For most products, their biggest environmental impact is at the extraction phase. That is why recycling can have a lower footprint than the use of virgin materials. The energy used to collect and remanufacture a product can be less than that used to extract a raw material and then make it into an end-product. Transportation emissions throughout these processes are also a key factor in assessing a product’s green footprint. 

The WARM Model

One of the ways to estimate the energy savings from recycling programs is the waste reduction model, also known as “WARM,” which takes advantage of the ability of lifecycle analysis to completely evaluate the environmental footprint of a product. Extraction and transportation emissions are particularly crucial.

In 1998, the U.S. Environmental Protection Agency’s Office of Resource Conservation and Recovery released version 1 of WARM, which was developed to give solid waste managers the ability to track greenhouse gas emissions from the full spectrum of waste management practices, including landfilling, combustion, composting, recycling and source reduction. This groundbreaking tool has proved to be invaluable in assessing the environmental implications of those different options for a wide variety of products.

As EPA notes in its website discussion, WARM “calculates emissions in metric tons of carbon equivalent, metric tons of carbon dioxide equivalent and energy units in million BTU across a wide range of materials types commonly found in municipal solid waste.” The original version of WARM covered 17 material types, including metals, plastics, organics, mixed paper and recyclables. It also included basic options – such as specifying the current mix of virgin materials, the type of landfill gas control system and the transportation distance to the waste management options – which are still available in WARM. 

WARM doesn’t cover every product that can be found in your garbage, but it covers a very high percentage. The newest WARM model – Version 13, released in June 2014 – includes 50 different material types, ranging from aluminum cans to yard trimmings. Among them are nine different paper products, such as corrugated boxes, newspapers and mixed paper; 10 organic materials, including bread, dairy, leaves and grass; nine plastics ranging from HDPE to PVC; personal computers; and other products.

WARM also includes 10 types of construction and demolition debris, such as asphalt, concrete, drywall and wood flooring. At this point, the only materials excluded from the WARM formula are relatively insubstantial parts of the waste stream.

A major benefit of WARM is that it is accessible – it is available in both a web-based calculator and in Excel. The EPA, however, is quick to note that the spreadsheet has more functionality than the calculator. The EPA is careful to remind potential users that WARM results are estimates, not absolute facts. Nonetheless, the WARM model has offered us tremendous insight into the trade-offs involved in deciding the most appropriate way to manage materials. m

Chaz Miller is director of policy/advocacy for the National Waste & Recycling Association. You can reach him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it. .