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Waste Reduction Model (WARM) Material Descriptions and Data Sources

This page provides a summary of the materials included in EPA’s Waste Reduction Model (WARM).

The table below includes a list of materials, a description of the material as defined in each material’s primary data source and citations for primary data sources.

WARM Material WARM Data Source Definition Primary Data Source Data Source Year Title/Notes
Aluminum Cans Aluminum cans represent cans produced out of sheet rolled aluminum ingot. PE Americas 2010 Life Cycle Impact Assessment of Aluminum Beverage Cans
Aluminum Ingot Aluminum ingot is processed from molten aluminum in the form of a sheet ingot suitable for rolling, extruding, or shape casting. Thus, it serves as a pre-cursor to manufacture of aluminum products such as aluminum cans. It can serve as a proxy for certain aluminum materials such as electrical transmission and distribution wires, other electrical conductors, some extruded aluminum products, aluminum product cuttings, joinings and weldings, and consumer durable products such as home appliances, computers, and electronics. Aluminum Association 2011 Copy of Data for ICF-EPA_Nd.xls. Spreadsheet updated by Neil D'Souza, PE International for ICF International and EPA in response to Life Cycle Impact Assessment of Aluminum Beverage Cans
PE Americas 2010 Life Cycle Impact Assessment of Aluminum Beverage Cans
Steel Cans Steel cans represent three-piece welded cans produced from sheet steel which is made in a blast furnace and basic oxygen furnace (for virgin cans) or electric arc furnace (for recycled cans). Franklin Associates 1998 Background Document A: A Life Cycle Inventory of Process and Transportation Energy for Eight Different Materials
Copper Wire Copper wire is used in various applications including power transmission and generation lines, building wiring, telecommunication, and electrical and electronic products. Franklin Associates 2002 Energy and Greenhouse Gas Factors for Personal Computers: Final Report
Glass Glass represents glass containers (e.g., soft drink bottles and wine bottles) EPA 2015 Advancing Sustainable Materials Management: Facts and Figures 2013
HDPE HDPE (high-density polyethylene) is usually labeled plastic code #2 on the bottom of the container, and refers to a plastic often used to make bottles for milk, juice, water and laundry products. It is also used to make plastic grocery bags. Franklin Associates, American Chemistry Council 2010 Cradle-to-Gate Life Cycle Inventory of Nine Plastic Resins and Two Polyurethane Precursors. Revised Final Report
LDPE LDPE (Low-density polyethylene), usually labeled plastic code #4, is often used to manufacture plastic dry cleaning bags. LDPE is also used to manufacture some flexible lids and bottles. Franklin Associates, American Chemistry Council 2010 Cradle-to-Gate Life Cycle Inventory of Nine Plastic Resins and Two Polyurethane Precursors. Revised Final Report
PET PET (Polyethylene terephthalate) is typically labeled plastic code #1 on the bottom of the container. PET is often used for soft drink and disposable water bottles, but can also include other containers or packaging. Franklin Associates, American Chemistry Council 2010 Cradle-to-Gate Life Cycle Inventory of Nine Plastic Resins and Two Polyurethane Precursors. Revised Final Report
LLDPE LLDPE (linear low-density polyethylene) is used in high-strength film applications. Compared to LDPE, LLDPE's chemical structure contains branches that are much straighter and closely aligned, providing it with a higher tensile strength and making it more resistant to puncturing or shearing. Franklin Associates, American Chemistry Council 2010 Cradle-to-Gate Life Cycle Inventory of Nine Plastic Resins and Two Polyurethane Precursors. Revised Final Report
PP PP (Polypropylene) is used in packaging, automotive parts, or made into synthetic fibres. It can be extruded for use in pipe, conduit, wire, and cable applications. PP's advantages are a high impact strength, high softening point, low density, and resistance to scratching and stress cracking. A drawback is its brittleness at low temperatures Franklin Associates, American Chemistry Council. 2010 Cradle-to-Gate Life Cycle Inventory of Nine Plastic Resins and Two Polyurethane Precursors. Revised Final Report
PS (polystyrene) GPPS (general purpose polystyrene) has applications in a range of products, primarily domestic appliances, construction, electronics, toys, and food packaging such as containers, produce baskets, and fast food containers (ICIS, 2011d). Franklin Associates, American Chemistry Council 2010 Cradle-to-Gate Life Cycle Inventory of Nine Plastic Resins and Two Polyurethane Precursors. Revised Final Report
PVC PVC (Polyvinyl Chloride) is produced as both rigid and flexible resins. Rigid PVC is used for pipe, conduit, and roofing tiles, whereas flexible PVC has applications in wire and cable coating, flooring, coated fabrics, and shower curtains. Franklin Associates, American Chemistry Council 2010 Cradle-to-Gate Life Cycle Inventory of Nine Plastic Resins and Two Polyurethane Precursors. Revised Final Report
PLA Polylactic acid or PLA is a thermoplastic biopolymer constructed entirely from annually renewable agricultural products, e.g., corn, and used in manufacturing fresh food packaging and food service ware such as rigid packaging, food containers, disposable plastic cups, cutlery, and plates Natureworks, LLC 2010 Technical data sheets by Application.
U.S. Life Cycle Inventory Database 2010 Data Module Report: NatureWorks Polylactide Biopolymer (Ingeo).
Corrugated Containers Corrugated cardboard boxes made from containerboard (liner and corrugating medium) used in packaging applications. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Magazines/Third-class Mail Third Class Mail is now called Standard Mail by the U.S. Postal Service and includes catalogs and other direct bulk mailings such as magazines, which are made of coated, shiny paper. This category represents coated paper produced from mechanical pulp. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Newspaper Newspaper represents uncoated paper made from 70% mechanical pulp and 30% chemical pulp. For the carbon sequestration portion of the factor, it was assumed that the paper was all mechanical pulp. Franklin Associates 1998 Background Document A: A Life Cycle Inventory of Process and Transportation Energy for Eight Different Materials
Office Paper Office paper represents paper made from uncoated bleached chemical pulp. Franklin Associates 1998 Background Document A, Attachment 1 : Partial LCI for Boxboard and Paper Towels
Phonebooks Phonebooks represent telephone books that are made from paper produced from mechanical pulp. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Textbooks Textbooks represent books made from paper produced from chemical pulp. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Dimensional Lumber Lumber includes wood used for containers, packaging, and building and includes crates, pallets, furniture and dimensional lumber like two by fours. EPA 2015 Advancing Sustainable Materials Management: Facts and Figures 2013
Medium-density Fiberboard Fiberboard is a panel product that consists of wood chips pressed and bonded with a resin. Fiberboard is used primarily to make furniture. EPA 1995 AP 42, Volume I, Fifth Edition (US EPA)
Food Waste (non-meat) Food Waste (non-meat) is a weighted average category representing non-meat food waste in the U.S. waste stream, based on the share of grains, fruits and vegetables, and dairy products in USDA’s loss-adjusted food availability survey. The mix is assumed to be 22 percent dairy products, 61 percent fruits and vegetables, and 16 percent grains. USDA 2012 "Food Availability (per Capita) Data System – 2010". U.S. Department of Agriculture Economic Research Service
Food Waste (meat only) Food Waste (meat only) is a weighted average category representing meat waste in the U.S. waste stream, based on the share of poultry and beef in USDA’s loss-adjusted food availability survey. The mix is assumed to be 46 percent beef and 54 percent poultry. USDA 2012 "Food Availability (per Capita) Data System – 2010". U.S. Department of Agriculture Economic Research Service
Beef Beef includes the upstream emissions and energy associated with the production of beef cattle in the United States, including the energy and emissions associated with feed production. Battagliese et al. 2013 Battagliese, T., Andrade, J., Schulze, I., Uhlman, B., and Barcan, C. (2013). More Sustainable Beef Optimization Project. Phase 1 Final Report, June 2013. Submitted by BASF Corporation.
Poultry Poultry includes the upstream emissions and energy associated with the production of broiler chicken (i.e., domesticated chickens raised specifically for meat production), including the energy and emissions associated with feed production. Pelletier 2008 Pelletier, N. 2008. “Environmental performance in the US broiler poultry sector: Life cycle energy use and greenhouse gas, ozone depleting, acidifying and eutrophying emissions,” Agricultural Systems 98 (2008): 67-73.
Grains The Grains emission factor consists of a weighted average of the relative amounts of grain products in the municipal waste stream, consisting of wheat flour, corn and rice. USDA 2000-2009 LCA Digital Commons
Bread The bread emission factor consists of the upstream emissions and energy associated with wheat flour production, as well as the additional energy used to bake it into bread. USDA 2004-2009 LCA Digital Commons
Espinoza-Orias et al. 2011 Espinoza-Orias, N., H. Stichnothe, and A. Azapagic. 2011. “The Carbon Footprint of Bread”. International Journal of Life Cycle Assessment, (2011) 16:351–365
Fruits and Vegetables Fruits and vegetables represents the average fresh fruits and vegetable components of food waste. It consists of a weighted average of the six most common fruits and vegetables in the municipal waste stream, including apples, bananas, melons, oranges, potatoes, and tomatoes. Ecoinvent Centre 2007 Ecoinvent data v2.0. Ecoinvent reports No.1-25, Swiss Centre for Life Cycle Inventories, Dübendorf, 2007.
Luske, B. 2010 Luske, B. 2010. Comprehensive Carbon Footprint Assessment Dole Bananas. Soil and More International.
UC Davis 2009 UC Davis Cost and Return Studies.
Dairy Products Dairy products consists of a weighted average of the emissions associated with nearly the entire dairy product waste stream, including milk, cheese, ice cream, and yogurt. Innovation Center for U.S. Dairy 2010 Thoma, G., et al. 2010. “Global Warming Potential of Fluid Milk Consumed in the US: A Life Cycle Assessment.” Innovation Center for U.S. Dairy and University of Arkansas.
Yard Trimmings Yard trimmings are assumed to be 50% grass, 25% leaves, and 25% tree and brush trimmings from residential, institutional, and commercial sources. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Grass Grass consists of grass clippings from residential, institutional and commercial sources. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Leaves Leaves consist of fallen leaves from deciduous trees recovered from residential, institutional and commercial sources. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Branches Branches are assumed to be the woody clippings from trees and brush from residential, intuitional and commercial sources. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Mixed Paper Broad Definition Mixed paper is assumed to be 24% newspaper, 48% corrugated cardboard, 8% magazines, and 20% office paper. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Residential Definition Residential mixed paper is assumed to be 23% newspaper, 53% corrugated cardboard, 10% magazines, and 14% office paper. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Office Paper Definition Office mixed paper is assumed to be 21% newspaper, 5% corrugated cardboard, 36% magazines, and 38% office paper. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Mixed Metals Mixed metals are made up of 35% aluminum cans and 65% steel cans. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Mixed Plastics Mixed plastics are made up of 39% HDPE and 61% PET plastic. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Mixed Recyclables Mixed Recyclables are made up of approximately 1% aluminum cans, 3% steel cans, 6% glass, 1% HDPE, 2% PET, 54% corrugated cardboard, 7% magazines/third-class mail, 11% newspaper, 8% office papers, <1% phonebooks, <1% textbooks, and 5% dimensional lumber. See those definitions for details. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Food Waste Food waste consists of uneaten food and wasted, prepared food from residences, commercial establishments such as grocery stores and restaurants, institutional sources such as school cafeterias, and industrial sources such as factory lunchrooms. This emission factor contains a weighted average of all food types in the waste stream currently modeled in WARM, including beef, poultry, grains, fruits and vegetables, and dairy products. The mix is assumed to be 9% beef, 11% poultry, 13% grains, 49% fruits and vegetables, and 18% dairy products. USDA 2012 "Food Availability (per Capita) Data System – 2010". U.S. Department of Agriculture Economic Research Service
Mixed Organics Mixed organics are made up of 52% food waste and 48% yard trimmings. See those definitions for details. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Mixed MSW Mixed MSW (municipal solid waste) comprises the waste materials typically discarded by households and collected by curbside collection vehicles; it does not include white goods (e.g., refrigerators, toasters) or industrial waste. EPA 2006 Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks
Carpet Carpet represents broadloom residential carpet containing a mix of nylon, PET and PP components within the face fiber, primary and secondary backing, and latex used for attaching the backings. Plastics Europe 2005 Life-Cycle Inventory of Solid Strip Hardwood Flooring in the Eastern United States
Realff, M. 2011 Personal communication between Dr. Matthew Realff, Georgia Tech. and Adam Brundage and Nikita Pavlenko, ICF International
Personal Computers PCs are made up of a central processing unit (CPU) and a cathode ray tube (CRT) monitor. The components of the CPU and monitor include steel housing, internal electric components, the CRT, plastic casing, and circuit boards. In addition to these valuable components, PCs contain lead, brominated flame retardants and other potentially hazardous chemicals. Franklin Associates 2002 Energy and Greenhouse Gas Factors for Personal Computers: Final Report
Clay Bricks Bricks are produced by firing materials such as clay, kaolin, fire clay, bentonite, or common clay and shale. The majority of the bricks produced in the US are clay. In WARM, clay brick source reduction is considered to be the reuse of full bricks rather than the grinding and reusing of broken or damaged brick. EPA 2003 Background Document for Life-Cycle Greenhouse Gas Emission Factors for Clay Brick Reuse and Concrete Recycling
Concrete Concrete is a high-volume building material produced by mixing cement, water, and coarse and fine aggregates. In WARM, concrete is assumed to be recycled into aggregate, so the GHG benefits are associated with the avoided emissions associated with mining and processing aggregate. EPA 2003 Background Document for Life-Cycle Greenhouse Gas Emission Factors for Clay Brick Reuse and Concrete Recycling
Fly Ash Fly ash is a byproduct of coal combustion that is used as a cement replacement in concrete. EPA 2003 Background Document for Life-Cycle Greenhouse Gas Emission Factors for Fly Ash Used as a Cement Replacement in Concrete
Tires Tires represent scrap tires that have been disposed of by consumers and have several end uses in the U.S. market including as a fuel, in civil engineering, and in various ground rubber applications such as running tracks and molded products. Atech Group 2001 A National Approach to Waste Tyres
EIA 2009 2006 Manufacturing Energy Consumption Survey, Table 3.2: Fuel Consumption, 2006 for Synthetic Rubber
Corti, A. and Lombardi, L. 2004 End life tyres: Alternative final disposal processes compared by LCA
Athena Institute 2000 Life Cycle Analysis of Residential Roofing Products
Asphalt Concrete Asphalt concrete is composed primarily of aggregate, which consists of hard, graduated fragments of sand, gravel, crushed stone, slag, rock dust, or powder. Census Bureau 2001 Fuels and Electric Energy Report. U.S. Economic Census
Census Bureau 1997 Mining-Subject Series, Product Summary, U.S. Economic Census
Athena Sustainable Materials Institute 2001 Life Cycle Inventory for Road and Roofing Asphalt
National Renewable Energy Laboratory (NREL) 2009 U.S. Life-Cycle Inventory Database
Natural Resources Canada 2005 Canadian Industry Program for Energy Conservation c/o Natural Resources Canada
Levis, J.W. 2008 A Life-Cycle Analysis of Alternatives for the Management of Waste Hot-Mix Asphalt, Commercial Food Waste, and Construction and Demolition Waste
Asphalt Shingles Asphalt shingles are typically made of a felt mat saturated with asphalt. Fiberglass shingles are composed of asphalt cement (36 percent by weight), a mineral stabilizer like limestone or dolomite (40 percent), sand-sized mineral granules (38 percent), in addition to the organic or fiberglass felt backing (15 percent). Athena Sustainable Materials Institute 2000 Life Cycle Analysis of Residential Roofing Products
Cochran, K. 2006 Construction and Demolition Debris Recycling: Methods, Markets, and Policy
Construction Materials Recycling Association (CMRA) 2007 Recycling Tear-Off Asphalt Shingles: Best Practices Guide
Drywall Drywall, also known as wallboard, gypsum board, or plaster board, is manufactured from gypsum plaster and a paper covering. Venta, G. 1997 Life Cycle Analysis of Gypsum Board and Associated Finishing Products
Fiberglass Insulation Fiberglass insulation is produced from a blend of sand, limestone, soda ash, and recycled glass cullet, which accounts for about 40 percent of the raw material inputs. Lippiatt, B. 2007 Building for Environmental and Economic Sustainability (BEES)
Enviros Consulting 2003 Glass Recycling — Life Cycle Carbon Dioxide Emissions
Vinyl Flooring All vinyl flooring is comprised of polyvinyl chloride (PVC) resin along with additives such as plasticizers, stabilizers, pigments, and fillers. Lippiatt, B. 2007 Building for Environmental and Economic Sustainability (BEES)
European Council of Plasticisers and Intermediates (ECPI) 2001 Eco-profile of high volume commodity phthalate esters (DEHP/DINP/DIDP)
Franklin Associates 2007 Revised Final Report: Cradle to Gate Life Cycle Inventory of Nine Plastics Resins Polyurethane Precursors
ecoinvent Centre 2008 ecoinvent Database v2.1. Swiss Centre for Life Cycle Inventories
Wood Flooring Virgin hardwood flooring is produced from lumber. Coatings and sealants can be applied to wood flooring in “pre-finishing” that occurs at the manufacturing facility, or on-site. Bergman, R. and Bowe, S.A. 2008 Environmental impact of producing hardwood lumber using life-cycle inventory
Hubbard, S.S. and Bowe, S.A. 2008 Life-Cycle Inventory of Solid Strip Hardwood Flooring in the Eastern United States
Bergman, R. 2010 Personal communication between Richard Bergman, USDA Forest Service and Robert Renz and Christopher Evans, ICF International

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