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Household Emissions Calculator Frequent Questions
- How comprehensive is the calculator?
- What are the estimates in the calculator based on?
- Why does the calculator ask for my Zip code?
- How do I determine my average monthly electricity, natural gas, or fuel oil use?
- What if my utilities are included in my rent or condo fee?
- Why don’t you include emissions from air travel?
- What if I use public transportation?
- What if I am already taking the actions described in the calculator?
- When will I see the greenhouse gas and dollar savings reported by the calculator?
How comprehensive is the calculator?
There is a fine balance between providing the ability to capture all potential emission sources/actions and keeping the calculator easy to use. This calculator is one of the more comprehensive tools available. However, you may find that there are certain emission sources and/or actions that aren’t captured, or you may want a more detailed analysis. The “Related Links” box on the first page of the calculator provides links to other calculators that can provide more detail.
What are the estimates in the calculator based on?
The calculator’s equations and assumptions are based on a range of respected national and international sources. For a full list of sources and assumptions, visit the Assumptions and References page.
Why does the calculator ask for my Zip code?
Greenhouse gas emissions from electricity production vary widely across the country, depending on the mix of power sources used by electricity providers. The calculator uses your Zip code to pull the appropriate emissions value per kilowatt-hour for your area. EPA does not keep your Zip code information and it cannot be used to identify you.
How do I determine my average monthly electricity, natural gas, or fuel oil use?
Because your energy consumption can vary widely by season, it’s best to total up your consumption (or the amount you paid) over an entire year and divide by 12. Most utility bills will tell you how much electricity, natural gas, or fuel oil you consumed each month, in addition to how much you paid. If you don’t keep your utility bills, ask your utility company to provide a summary for the previous year.
What if my utilities are included in my rent or condo fee?
If possible, check with your building manager for information specific to your unit. If the information is not available, use the national averages that are listed throughout the calculator.
Why don’t you include emissions from air travel?
EPA does not currently include airline travel in the household greenhouse gas emissions calculator, but may do so in the future. Greenhouse gas emissions per aircraft passenger mile vary according to factors such as aircraft type, length of trip, occupancy rates, and the weight of baggage and cargo. Furthermore, scientists are still studying the climatic effect of greenhouse gas emissions released at high altitudes, as well as the effects of contrails (the white trails that often appear in the sky behind airplanes). As a rough estimate, based on data from the 2005 National Transportation Statistics and EPA’s Greenhouse Gas Inventory, the average domestic commercial flight in 2005 emitted 0.59 pounds of CO2 per passenger mile. You may use this figure to roughly estimate your emissions associated with airline travel, using the complete in-air distances shown on your plane tickets or travel summary (including travel to hubs that serve as transport points). You should also consider emissions associated with ground travel to and from the airport (i.e. the drive, cab, or train ride).
What if I use public transportation?
Good choice! In general, buses and trains emit less CO2 per passenger mile than household vehicles do. According to data from the Transportation Energy Data Book, Highway Statistics 2005, and EPA’s Greenhouse Gas Emissions Inventory, buses emitted an average of 0.24 lbs CO2 per passenger mile, and rail emissions range from 0.37 to 0.41 lbs CO2 per passenger mile (depending on whether it is transit rail, commuter rail, or intercity rail). The average CO2 emissions per passenger mile for an individual train or bus depend on the vehicle’s passenger load (i.e., the more passengers on board, the less CO2 emitted per passenger mile) as well the technologies and energy sources used by your public transportation system. For example, a subway system running on electricity that is produced mainly by hydropower will have lower greenhouse gas emissions than a system in a region where most electricity is produced by coal. City buses running on electricity, compressed natural gas, or biodiesel will have lower greenhouse gas emissions than those using conventional diesel. Your local transit authority may have more representative information for your area.
Whatever mode of travel you choose, there are things you can do to minimize your carbon and overall environmental footprint. When possible, it is better to choose mass transit. EPA has additional tips on how people can reduce their carbon footprint in the What You Can Do section of the site.
What if I am already taking the actions described in the calculator?
That’s great! Encourage others to follow your lead. You can also take additional steps to reduce your emissions, such as buying local produce, looking for products that have reduced packaging and/or have recycled content, or using public transportation. You’ll find suggestions for other activities in the What You Can Do section of EPA’s Climate Change site.
When will I see the greenhouse gas and dollar savings reported by the calculator?
All estimates are calculated on an annual basis. In other words, if you implement one of the actions listed in the calculator, it will take one full year to realize the estimated emission savings. Some of the actions listed in the calculator are behavioral changes and don’t have an upfront dollar cost. For these actions, it will take roughly one year of consistently adopting that behavior to realize the estimated dollar savings. For those actions listed in the calculator that are technological changes and have an upfront cost, the cost is spread over the technology’s lifetime and is subtracted from the estimated dollar savings for that year. For information on assumptions of upfront costs for each action, see the “cost (dollars)” column of the calculator.