Emissions Sources | Pounds of CO2 You Can Save Each Year
Emissions Sources
Transportation
Pounds of carbon dioxide equivalent are calculated with a simple algorithm derived from the U.S. EPA/Department of Energy Fuel Economy calculator at http://www.fueleconomy.gov/. Using that calculator, we specified low and high values for gas mileage. Using the results, we developed a linear equation expressing CO2 emissions as a function of gas mileage and miles driven. CO2 emissions take into account the full fuel cycle i.e., not only emissions at the tailpipe, but also emissions associated with production and refining of fuels.
"Typical" annual CO2 emissions of 17,000 pounds per vehicle based on 200 miles per week and a car that gets 22 miles per gallon. Source for typical values: Federal Highway Administration, 1999. Summary of Travel Trends, 1995 Nationwide Personal Transportation Survey.
Electricity
National average emissions factor for electricity is 1.64 pounds CO2 per kilowatt-hour. Source: The Cadmus Group, 1998. Regional Electricity Emission Factors Final Report.
"Typical" annual CO2 emissions of 20,000 pounds per household based on 1,000 kWh/month, which is the average used in most utility rate cases.
Natural Gas
Carbon coefficient for natural gas: 117 pounds of CO2 per million BTU, or 0.12 pounds per cubic foot of gas. Source: U.S. Environmental Protection Agency, 1999. U.S. Inventory of Greenhouse Gas Emissions and Sinks: 1990-1997.
"Typical" annual CO2 emissions of 11,000 pounds per houshold based on national average monthly consumption of 7,680 cubic feet of gas. Source: U.S. Energy Information Administration 1999. A Look at Residential Energy Consumption in 1997.
Fuel Oil
Carbon coefficient for distillate fuel (fuel oil): 161.44 pounds of CO2 per million BTU, or 22.29 pounds per gallon. Source: U.S. Environmental Protection Agency, 1999. U.S. Inventory of Greenhouse Gas Emissions and Sinks: 1990-1997.
"Typical" annual CO2 emissions of 14,500 pounds per household based on national average monthly consumption of 55 gallons of oil. Source: U.S. Energy Information Administration 1999. A Look at Residential Energy Consumption in 1997.
Waste Disposal
Estimates of greenhouse gas emissions from waste disposal were developed using national waste data and life-cycle greenhouse gas emission factors for waste management.
EPA's annual Characterization Report was the source of per capita waste generation and national average rates of recycling, composting, combustion, and landfilling by material type. Source: U.S. Environmental Protection Agency, 1999. Characterization of Municipal Solid Waste in the United States: 1998 Update.
Carbon dioxide equivalent emissions associated with household waste management were calculated using emission factors developed by the U.S. Environmental Protection Agency and presented in the Agency's report on greenhouse gas emissions from waste management and in the online WAste Reduction Model (WARM). These emission factors take into account the full material life cycle, i.e., not only emissions at the landfill, but also emissions and sequestration associated with production, manufacturing, remanufacturing, forest carbon storage due to reduced harvests, etc. For the fraction of waste that was landfilled, we applied emission factors corresponding to "national average recovery practices" (i.e., a weighted average of the emission factors for landfills without gas recovery, landfills with gas recovery and flaring, and landfills with gas recovery and electricity generation). Source: U.S. Environmental Protection Agency, 1998. Greenhouse Gas Emissions from Selected Materials in Municipal Solid Waste. WARM is available on EPA's GlobalWarming website at http://yosemite.epa.gov/OAR/globalwarming.nsf/content/ActionsWasteToolsWARM.html.
"Typical" annual CO2 emissions of 4,800 lbs were estimated based on a household of two people, per capita waste generation of 4.44 lbs/day, a 25 percent recycling rate, no source reduction, and the national average mix of recyclables.
Pounds of CO2 You Can Save Each Year
Transportation
Results are calculated with a simple algorithm derived from the DOE/EPA Fuel Economy website calculator at http://www.fueleconomy.gov.
Recycling
Emissions were estimated using a linear regression equation that defines the relationship between the rate of waste diversion (through source reduction and recycling) and greenhouse gas emissions.
Material-specific maximum rates of recycling and source reduction were established based on expert judgement. Calculations assume that it would be possible for households to recycle 100 percent of all recyclable materials generated as waste; however, the maximum rate of source reduction was determined to be 60 percent of waste generation.
Home Energy Use
Replacing incandescent light bulbs with compact fluorescents: Assumes that lights are on for 5.5 hours per day, or 2,000 hours per year, saving 94 kilowatt-hours per year per lamp.
Replacing old refrigerator with an ENERGY STAR® model: Assumes old model uses 1,600 kWh per year; ENERGY STAR model uses 550 kWh per year.
Turning up thermostat for central air conditioner: Assumes average household electricity use of 1,000 kWh per month, and that air conditioners account for 11.8 percent of residential electricity consumption. Source: EIA 1999. A Look at Residential Energy Consumption in 1997. Also assumes that turning up the thermostat by 1°F yields a 5 percent savings in electricity consumption from May through September. Source: Florida Solar Energy Center, 1996. Monitored Energy Use Patterns in Low-Income Housing. Note that the 5 percent savings is a conservative average estimate for the nation as a whole, based on the 13 percent savings reported in this study of Florida homes.
Turning down thermostat by 10°F in winter: Assumes $50 per month is spent on oil or gas. Assumes 5 percent savings for a 10 degree decrease (conservative estimate) based on U.S. Department of Energy fact sheet on automatic and programmable thermostats (DOE/GO 10097-375, March 1997). Assumes thermostat is turned down for 8 hours each night November through March.
Replacing single-glazed windows with ENERGY STAR windows: Assumes 1850 square-foot house, 250 square feet of glass, heating load of 6.95 Btu/square foot per degree-day with 6,300 heating degree-days. An R1 window transmits 1 Btu per square foot per degree-hour; an R4 window transmits 0.25 Btu per square foot per degree-hour. Source for calculations: Alex Wilson, BuildingGreen, Inc. (background calculations for the American Council for an Energy-Efficient Economy's Consumer Guide to Home Energy Savings).
Replacing an old boiler or furnace with an ENERGY STAR model: Assumes 1850 square-foot house, 6,300 heating degree-days, 81 MMBtu/year heating load. Source for calculations: Alex Wilson, BuildingGreen, Inc. (background calculations for the American Council for an Energy-Efficient Economy's Consumer Guide to Home Energy Savings).