Setting an Emissions Reduction Target
Following a Greenhouse Gas (GHG) Inventory, the next step is to create a Climate Action Plan (CAP) which specifies an overall GHG reduction target as well as specific targeted GHG reductions that will come from individual, well-defined activities and programs. Even if an inventory is not completed or a formal CAP is not planned, setting GHG emissions reduction targets can be used to prioritize activities based on their GHG reduction potentials.

This section focuses on how to go about setting the emission reduction targets and priorities for materials management policies and programs.

The Link between GHG Inventories and Setting Targets

The approach to setting emissions reduction targets is influenced by whether the jurisdiction responsible for a GHG Inventory and Climate Action Plan makes a decision to only target reductions from the inventory (the "Inventory Purist Approach") or decides to include reductions that may fall outside of the inventory (the "Inventory Pragmatist Approach").

“Inventory Purist Approach”
In this approach, a community GHG inventory dictates what can be counted towards GHG reductions. As a result, the methods used for conducting a GHG inventory will determine which actions will contribute to meeting GHG reduction targets. If, for example, emissions from out-of-state production of goods consumed in a community aren’t part of the inventory, then any reductions in emissions resulting from local consumers purchasing lower-carbon products or participating in waste prevention or reuse activities, won't be included in the targets set or the results reported. Similarly, if a community-based recycling program collects recyclables and sends them to a mill in another community, the resulting GHG reductions (at the mill) won't be counted unless the full life-cycle emissions associated with the materials used and recycled in a community are included in the baseline GHG inventory. For materials management, this "purist" approach requires a much greater effort in ensuring that the baseline GHG inventory reflects emissions associated with materials management. Currently, most inventories do not account for lifecycle emissions from material use and consumption.

This approach may be preferred if a community is just building its inventory and materials management can be included, if the inventory already includes materials management, or if a community is open to revising the existing inventory framework. The benefit of this “purist” approach is that the boundaries of the inventory are clear and consistent and, once incorporated, materials management will be consistently tracked and given equal “billing” in the inventory and throughout the process of planning and tracking climate actions.

The main difficulty of this approach is that changing existing inventory methods can be difficult, depending on the approach that is taken. In addition, the national government is required to report using the IPCC Guidelines for National Greenhouse Gas Inventories which do not take a system or consumption approach. Some communities want to report in a way that is consistent with the national inventory.

If a community decides to take this "purist approach," then they should consult the Inventories page for approaches to incoporate materials management in GHG inventories. As discussed in the Inventories page, one way some communities have approached including materials management in their GHG inventory is to prepare both a conventional inventory and a companion systems-based inventory using one of the approaches described in the Inventory page. In this way, targets for emissions reductions from materials management can still be related to the GHG Inventory.

“Inventory Pragmatist Approach”
In this approach, credit is taken for GHG emission reductions even if the emissions reduced are not included in the baseline GHG inventory. The pragmatic approach recognizes the challenges associated with creating a GHG inventory that includes all the emissions under the control or influence of a community, and it does not limit the actions taken to reduce GHG emissions to only those actions that reduce the inventory inside the boundaries of their jurisdiction. In the pragmatist approach, a community may work on source reduction and recycling projects that have associated GHG reductions in another jurisdiction and yet apply the reductions in GHG as a "credit" against their overall target and/or inventory. This is similar to carbon offset programs where steps are generally taken to first minimize direct emissions, and then "credit" is taken for other emissions reduced elsewhere that, in theory, balance some or all of the remaining direct emissions. In the pragmatist approach, a community looks at their overall emissions inventory and counts emissions reduced “off inventory” (via source reduction, recycling) in a manner similar to offsets, noting that they contributed to emissions reductions, but not from locally inventoried sources.

This approach may be preferred if a community's inventory does not includes materials management and there is no plan to change to the inventory to include it. The benefit of this approach is that it offers maximum flexibility to the community in undertaking materials management types of GHG reducing activities. Activities that yield reductions not already in the inventory can still be undertaken and counted toward the overall target.

One problem with this approach is that it makes the inventory process a little less precise and bounded. It may also result in the double-counting of emissions reductions if materials not used in one community result in reduced manufacturing emissions in another state or country that are also counted there. Double-counting is a potential problem in national inventories, where national accounts are summed together for a global total. However, this is not typically done with state or local inventories. Double-counting is also a potential problem if emissions (and reductions) are "owned" and have financial value. Again, in the context of state and local inventories, this is not typically the case. When it comes to materials management and state or local GHG inventories, concerns regarding double-counting between jurisdictions are usually unwarranted.


There are a variety of possible methods to estimate the emissions reduction, or reduction potential, associated with materials management. Many of the available tools and methods are mentioned below (with links to further details). In most cases, these tools include some degree of lifecycle approach to assessing materials management related GHGs.

Taking a broad or specific approach to setting targets:
If a community wants to evaluate the GHG reduction potential of changing how materials are purchased or used, then it needs information on the quantities of materials purchased.

If a community wants to evaluate the GHG reduction potential of changing how discards are managed, it needs to have a good grasp on the composition and quantity of material and waste streams.

Some communities set broad goals for their materials management programs such as reducing waste generation 10 percent in the next 20 years or increasing the recycling rate to 50 percent, while some prefer to set more specific goals such as adding food waste to residential curbside composting. Some will do both, having specific programmatic efforts defined to meet a larger goal. Most commonly, communities have data on total waste disposal, and some communities also have data on recovery. Obtaining a good grasp on the composition of materials that make up total waste generation (disposal + recovery) can be tricky because most waste composition studies only look at disposal and leave out recovered materials. Some communities can combine waste composition data with recovery estimates to create a profile of total waste generated.

If a community takes the broad approach, it can use the composition detail to estimate the emissions for a target of an overall 10 percent reduction in waste generation by making forecasts that the waste composition stays the same, or changes in a certain way. If the community takes a specific approach, it will need the composition to estimate quantities of affected materials that will be managed in some other way and the emissions related to changes that are expected.

For an example of a plan that incorporates both broad targets and specific goals, consider the City of Portland Climate Action Plan. Page 13 projects that recycling and waste prevention will contribute 6 percent and 15 percent to the City's overall GHG reduction totals, respectively. The Plan identifies some specific actions (such as adding food waste to residential yard waste composting) but in other areas is less specific. This is somewhat of a punt - but a useful punt. It commits City resources to achieve broad results, without binding staff to a specific approach.

The City of Hayward Climate Action Plan offers an example of very detailed and specific goal setting. A number of specific actions were evaluated for their GHG reduction potential. Certain actions were selected for inclusion in the City's Climate Action Plan. The cumulative GHG reductions from this package of selected actions are then rolled together and incorporated into the City's larger goal for emissions reduction.

Timing of Emissions Reductions:
For some materials management practices in any given year, the resulting emissions reductions may occur in future years. This is essential to keep in mind when working in the context of a larger community inventory, as other emissions are reported in the years in which they actually occur. For the purpose of decision-making, different materials management options need to be compared on a life-cycle basis - not just on the basis of emissions that occur in the year of action. Link to this page for additional details.


EPA’s WAste Reduction Model (WARM) is a tool for assessing the GHG emissions of a baseline and an alternative waste management method for handling any of 26 materials and 8 mixed materials categories. WARM is the most common tool used to predict and estimate GHG emissions reductions from materials management strategies. WARM was created “to help solid waste planners and organizations track and voluntarily report greenhouse gas emissions reductions from several different waste management practices.” (From the WARM website). While WARM was not originally designed to be used as an inventory tool, it is possible to use WARM to estimate the life cycle GHG emissions and emissions reductions associated with a variety of material uses and end-of-life practices in a systems based approach – both projected (future) and actual (current). (WARM is available both as a Web-based calculator and as a Microsoft Excel spreadsheet (355K WinZip archive).)

WARM calculates and totals GHG emissions of baseline and alternative waste management practices—source reduction, recycling, combustion, composting, and landfilling. The model calculates emissions in metric tons of carbon equivalent (MTCE), metric tons of carbon dioxide equivalent (MTCO2E), and energy units (million BTU) across 34 material types commonly found in municipal solid waste (MSW). The emission factors represent the GHG emissions associated with managing 1 short ton of MSW in a specified manner. GHG savings should be calculated by comparing the emissions associated with the alternative scenario with the emissions associated with the baseline scenario, as opposed to simply multiplying the quantity by an emission factor. Without the comparison, part of the emissions savings or cost will be excluded.

Planning: Communities can use WARM to analyze possible waste management scenarios and develop optimum scenarios for reducing emissions from waste management. By design, WARM is well suited to identifying material-specific emissions by waste management scenario. Should you target corrugated cardboard for increased recycling vs. incinerating it? Or would you be better off to target personal computers for increased recycling? Which materials will give you the bigger emissions reductions if source reduced? If a community has good data on your solid waste and how it is managed currently, WARM can be used to provide good relative comparisons of emissions reductions potentials of source reducing or recycling various materials versus landfilling or incinerating them. As such, it can be useful in setting programmatic direction. The State of Minnesota Pollution Control Agency, for example, was charged with working with stakeholders to develop a plan for meeting a given emissions reduction target for solid waste management. The stakeholder group used WARM to run several scenarios for possible changes in the system and determine which would reach the target. (Minnesota Pollution Control Agency: Stakeholder Process to Achieve Greenhouse Gas Reduction, Energy Conservation, and Environmental Protection through Integrated Solid Waste Management)

Setting targets: Some communities use WARM to help set their targets as either tons of materials or GHGs. Fort Collins (Colorado), for example, used WARM to determine the anticipated GHG savings from their existing recycling programs (such as curbside recycling) and to set the targets for GHG reduction in 2012 and 2020 from new programs such as enhanced PAYT (pay-as-you-throw) and starting a drop-off site for construction and demolition debris. In these cases, it was first necessary for Fort Collins to estimate the amounts of materials that would be reduced or recycled through these programs and then run those estimates through the WARM model. (See Fort Collins example here.)

In sum, WARM is one of the best tools available for state and local governments to estimate the GHG emissions associated with prevention, recycling, and composting. WARM is not without limitations. More about WARM and its limitations is summarized here.

Environment Canada's GHG Calculator for Waste Management

Environment Canada's GHG Calculator for Waste Management is similar to and based on US EPA's WARM tool, although it uses Canadian GHG emission factors for materials commonly occurring in the Canadian waste stream. It includes anaerobic digestion among the waste management options and includes several new material types such as electronics and large appliances, also known as "white goods". Additionally, it estimates GHG emissions from provincial fuel generation through an analysis of where each step of the manufacturing process happens. The tools is available as an Excel spreadsheet that can be obtained free of charge at the link above.

EPA SMART BET Calculator

SMART BET (Saving Money and Reducing Trash Benefit Evaluation Tool) is designed to help community waste managers decide whether unit-based pricing for solid waste management (also known as Pay-As-You-Throw or PAYT) is the right model for their town or city.

SMART BET allows users to input readily available information, such as tons of waste landfilled and recycled annually, local population, and landfill tip fees. The user may also provide a more detailed breakdown of the disposal and recycling streams, if this information is available. The tool then combines this information with nationwide average waste disposal data, typical PAYT results, and greenhouse gas emission factors originally created for EPA's Waste Reduction Model (WARM) to provide the greenhouse gas and cost savings that your community is likely to see after implementation of SMART.


The Climate and Air Pollution Planning Assistant (CAPPA) is a free Excel-based decision making tool from ICLEI-USA designed to help locals "explore, identify, and analyze potential climate and air pollution emissions reduction opportunities." The advantage of CAPPA is that it allows communities to consider options for GHG reductions over a wide range of sectors, such as electricity and transportation, simultaneously. Opportunities include several for materials and waste:
  • Composting (kitchen and yard waste)
  • Methane flaring at landfills
  • Recycling (expanding commercial, curbside, and construction materials recycling)
  • Waste reduction (Pay-As-You-Throw, reuse facilities)
For each option, CAPPA quantifies two types of avoided GHGs associated with the annual activity: (1) approximation of the annual landfill methane reduction and (2) avoided lifecycle emissions. Both numbers are based on WARM emission factors. Some outstanding concerns for using CAPPA relate to the current lack of methodology to address the timing of emissions (Link to this page for additional details). Specifically, the algorithm for prioritizing options for emissions reductions currently only credits recycling, composting, and source reduction by the avoided annual landfill methane reduction.

San Rafael and San Carlos are two examples of cities that use CAPPA to project future potential emissions reductions, including those from materials and waste. (, //

US EPA's MSW Decision Support Tool

The MSW Decision Support Tool (DST) is intended for use by solid waste planners at state and local levels to analyze and compare MSW management strategies with respect to GHGs and also cost, energy consumption, and environmental releases to air, land, and water (more than 30 air- and water-borne pollutants). It models emissions associated with municipal waste activities, including source reduction, waste collection and transportation, materials recovery facilities, transfer stations, compost facilities, combustion and refuse-derived fuel facilities, and landfills. The MSW DST can be used to optimize the system given constraints, for example to determine the most cost-effective strategy for reaching specific policy goals, such as diverting 40 percent landfill waste. Text taken from MSW DST requires detailed input information about the community's waste stream composition and operating information. Currently it is only available via support from Research Triangle Institute (contact Keith Weitz -

Examples where communities have used MSW DST include: California's 2010 Life Cycle Assessment and Economic Analysis of Organic Waste Management and GHG Reduction Options and St. Paul, Washington State, and a composting facility in North Carolina.

EPA has done a comprehensive comparison of the WARM and MSW-DST tools. EPA does not recommend one in lieu of the other, but rather recommends choosing your tool based on the scope of analysis. Great effort has been made to reconcile differences between the two tools, such that given identical assumptions, the tools would yield identical results. The only major methodological difference between the tools is treatment of carbon storage and sequestration. MSW-DST reports carbon storage and sequestration separately. As of early 2011, MSW DST is not available free-of-charge, while WARM is. There are plans to make MSW-DST available at no cost in the future.

Process Life Cycle Analysis (LCA)

Process LCA is what most people think of when they hear of life cycle analysis. Process LCA maps the flows of materials through processes (mining, smelting, refining, extruding, transporting, etc.) and assigns resource flows and pollutant releases to each. EPA's WARM tool and MSW DST, and Environment Canada's GHG Calculator for Waste Management, are all derived from process LCAs of manufacturing products from virgin and recycled feedstocks, and end-of-life processes such as composting, incineration, and landfilling.

In most cases, off-the-shelf tools such as WARM will serve the needs of state and local governments, particularly when it comes to estimating the GHG emissions reductions or reduction potential of many prevention, recycling, and composting activities. Occasionally, however, special questions will arise regarding management methods or materials that have not been documented elsewhere. For example, WARM uses an average for all carpet. A green building program focusing on purchasing guidelines might want to know more about different types of carpet, such as Nylon-6 vs. Nylon-6,6 vs. wool. To answer these types of more detailed questions, process LCAs should be considered.

The greatest limitation of process LCAs is that they tend to be expensive and time consuming. However, the information gained from process LCAs is often very valuable. A few examples of process LCAs that have been commissioned by state and local governments, with a focus on materials management, are provided here.


EIO-LCA (Economic Input Output Life Cycle Assessment) is an input/output life cycle analysis tool produced by the Green Design Institute at Carnegie Mellon University. Certain EIO-LCA models (including a 2002 model of the US economy) are available free of charge via the Internet.

While EIO-LCA is a life cycle analysis tool, it operates very differently than "traditional" process LCAs (described above). While process LCAs are typically denominated in terms of mass, following the flows of materials through a supply chain and associated industrial processes, input-output LCAs are denominated in terms of dollars, following the flow of money through the economy.

EIO-LCA only evaluates life-cycle emissions upstream, associated with manufacturing, resource extraction and supply chains. It does not evaluate the full life cycle emissions (including use and end-of-life) for any given product or material. As such, its applicability for informing recycling programs is limited. In contrast, EIO-LCA can offer some rough estimates of the GHG impacts associated with producing a variety of commodities, and by extension, the GHG benefits of not producing those commodities (resulting from waste prevention, reuse, or other "sustainable consumption" efforts).

More information about EIO-LCA is provided here.