Introduction

Though the greenhouse effect is a natural phenomenon, the concern is the degree to which it is being augmented by human activities. A multitude of human activities, such as driving cars, using electricity, raising cattle, growing rice, and landfilling waste, all contribute to greenhouse gas emissions. As the amount of greenhouse gases in the atmosphere increases, their ability to trap heat in the Earth’s lower atmosphere is concomitantly causing a rise in the Earth’s average surface temperature. Deforestation magnifies the problem because there are fewer plants to act as a sink for the greenhouse gases accumulating in the atmosphere. This enhanced greenhouse effect is implicated in climate change that can have far-reaching consequences for Earth’s ecosystems as well as for human communities.

In this lab, you will calculate your household’s carbon footprint and explore your personal contributions to this enhanced greenhouse effect. The lab also includes ideas for how to reduce your greenhouse gas emissions.

Lab Directions

1. Use the household carbon footprint calculator developed by the Cool Climate Network.
2. On the Intro page, enter the information about your household size and household annual income. Do not enter information about your location yet. You will see the carbon footprint information for an average U.S. household that matches your parameters of family size and income. Enter the total carbon footprint for the U.S. in Table 12.1 on the Lab Response form.
3. Still on the Intro page, type in information about your location. First type in your state, then your county, then your city. If your city is not included in the program, select the closest city to you in your county. Each time you type in a location, notice if the carbon footprint information changes. Enter the total carbon footprint for your state, county, and city in Table 12.1 on the Lab Response form.
4. Click the Refine Your Estimate button on the bottom to start calculating your household carbon footprint.
5. Calculating your travel footprint: Add or subtract the number of vehicles your family owns, including details about the miles driven per year and the mileage per gallon. To calculate your carbon footprint associated with public transit and air travel, click the Advanced button and enter details about miles traveled by bus and train, and add the number of flights in each category (e.g., short, medium, long, or extended). Enter the details of your travel carbon footprint in Table 12.2 as follows:
   • Calculate the total size of your household’s travel footprint by adding up all the travel categories (vehicles, public transit, and air travel) and enter the information in column 2.
   • Identify the largest contributor to your travel footprint (vehicles, public transit, or air travel) and enter that information in column 3.
   • Enter the comparison to similar households in your community (reported below the travel data in the graph) as percent better, worse, or same in column 4.
6. Calculating your housing footprint: Fill in all the information related to your energy and water use and the size of your home. Enter the details of your housing carbon footprint in Table 12.2 as follows:
   • Calculate the total size of your household’s housing footprint by adding up all the housing categories (electricity, heating, construction of living space, and water) and enter the information in column 2.
   • Identify the largest contributor to your housing footprint (electricity, heating, construction of living space, or water) and enter that information in column 3.
   • Enter the comparison to similar households in your community (reported below the housing data in the graph) as percent better, worse, or same in column 4.
7. Calculating your food footprint: Click on the Advanced button, as you will get a more accurate calculation of your food footprint. Move the slider to indicate the average daily servings for each food group. Enter the details of your food carbon footprint in Table 12.2 as follows:
   • Calculate the total size of your household’s food footprint by adding up all the food categories (meat/fish/eggs, grains, dairy, fruit/vegetables, and snacks/drinks) and enter the information in column 2.
   • Identify the largest contributor to your food footprint (meat/fish/eggs, grains, dairy, fruit/vegetables, or snacks/drinks) and enter that information in column 3.
   • Enter the comparison to similar households in your community (reported below the food data in the graph) as percent better, worse, or same in column 4.
8. Calculating your shopping footprint: Click on the Advanced button for Goods and Services, as you will get a more accurate calculation of your shopping footprint. Enter approximate dollar amounts spent in each category for your household. Enter the details of your shopping carbon footprint in Table 12.2 as follows:
   • Calculate the total size of your household’s goods footprint by adding up all the goods categories (furniture/appliances, clothing, entertainment, paper/reading, personal care/cleaning, auto parts, and medical) and enter the information in column 2.
   • Identify the largest contributor to your goods footprint (furniture/appliances, clothing, entertainment, paper/reading, personal care/cleaning, auto parts, or medical) and enter that information in column 3.
   • Enter the comparison to similar households in your community (reported below the goods data in the graph) as percent better, worse, or same in column 4.
   • Calculate the total size of your household’s service footprint by adding up all the service categories (health care, information/communication, medical, vehicle service, personal business/finance, household maintenance/repair, organizations/charity, and other services) and enter the information in column 2.
   • Identify the largest contributor to your services footprint (health care, information/communication, medical, vehicle service, personal business/finance, household maintenance/repair, organizations/charity, or other services) and enter that information in column 3.
   • Enter the comparison to similar households in your community (reported below the services data in the graph) as percent better, worse, or same in column 4.
9. Click Next and it will take you to the final screen: Reduce Your Impact. On this screen you will see a total carbon footprint calculation. Enter this number in the last row of Table 12.1 and Table 12.2. In addition, in Table 12.2, identify the largest contributor to your household footprint (travel, housing, food, goods, or services) and the comparison to similar households in your community (reported at the top along with the total carbon footprint) as percent better, worse, or same and enter this data in the appropriate column of the last row.
10. Answer questions 1-3 on the Lab Response form.
11. On the Reduce Your Impact screen, there are various actions to reduce carbon footprints listed for three categories: transportation, housing, and food. In each category, identify actions that you would be willing to take to reduce your carbon footprint. NOTE: If you already engage in that action, it will not reduce your carbon footprint, so commit to new actions. By clicking on the action, you will get more detailed information about the action and can make changes to the level of your action. Once you have made the changes you want, pledge the action to see how it changes your carbon footprint. Pledge a minimum of 10 actions and complete Table 12.3 based on this information.
12. Answer questions 4-5 on the Lab Response form.
13. One of the ways to reduce your carbon footprint, as identified in the calculator, is the planting of trees. But the calculator is narrow in that it only focuses on the energy benefits, when in reality, in addition to sequestering carbon and reducing energy use by providing shade, trees provide a variety of other ecosystem services: controlling stormwater runoff, stabilizing soil, improving air and water quality, and providing wildlife habitat. Explore the value of trees on the Arbor Day Foundation website and scroll down the page to the National Tree Benefit Calculator. Enter your zip code to identify your location.  You can choose to do this analysis for a tree of your choice: a tree that already grows in your yard, a favorite tree in a local park, etc. Follow the prompts to select the tree’s species, determine the size of the tree (diameter), and select the land-use type of your chosen tree. Once you have your calculation, scroll through each of the tabs to learn about the benefits your selected tree provides and complete Table 12.4 based on this information. Be sure to include the units of measurement in each case.
14. In the Tree Benefit Calculator under the CO₂ tab, the value of a tree in influencing carbon footprints is described in two different ways. Trees help to sequester carbon, which means that they remove carbon that is already in the atmosphere and “lock” it up in their roots, trunks, stems, and leaves. Secondly, trees prevent carbon from being released in the first place by providing shade, thus reducing the need for air conditioning and the combustion of greenhouse gas-emitting fossil fuels used to produce electricity.

Assume that you decided to plant sufficient trees to offset your household’s carbon footprint. How many trees of the species and size you selected for the Tree Benefit calculation above will it take to absorb the carbon dioxide you release in a year?

HINT 1: Remember not to use the total carbon reduction value for your tree. Instead, just use the amount of carbon sequestered. The carbon you are looking to offset will already be in the atmosphere, so you are looking to the trees to remove it.

HINT 2: Since your carbon footprint was calculated in tons and the carbon sequestration potential of the tree was calculated in pounds, you first have to convert one of the measures so that they are both in the same units. Here is the conversion formula: 1 ton = 2,000 pounds.

15. Answer questions 6-7 on the Lab Response form.

References

Cool Climate Network. (n.d.). Household Calculator. Retrieved April 15, 2025, from https://coolclimate.berkeley.edu/index

Arbor Day Foundation. (n.d.). National Tree Benefit Calculator. Retrieved April 15, 2025, from https://www.arborday.org/value

Lab 12 Response: Energy Audit

Questions

1. How does your household’s total carbon footprint compare to similar households in your town, county, state, and in the U.S.? Discuss possible reasons for any differences.
2. Discuss what you learned about your household’s contributions to greenhouse gas emissions from this audit. Specifically, discuss what you learned about contributions in each category (travel, housing, food, goods, and services). What surprised you? What aspects do you feel good about due to low greenhouse gas emissions? What elements could/should be changed to reduce greenhouse gas contributions?
3. How do the details of your carbon footprint compare to similar households in your town? For each category (travel, housing, food, and shopping), discuss possible reasons for any differences.
4. Explain why you picked the actions that you did in Table 12.3. What will the overall reduction in your carbon footprint be as a result of implementing all 10 actions? Discuss the cost–benefit analysis associated with implementing the actions you selected (savings versus upfront costs relative to reduction in carbon footprint). Will making these changes be worth it, in your estimation? Explain your thinking.
5. Reflect on all the actions available (not just the ones you selected). Do you think such individual actions would make a difference in reducing the enhanced greenhouse effect and addressing climate change in the long run? Explain your thinking.
6. Was planting trees one of the actions you committed to as a way to reduce your household’s carbon footprint? Explain why you did or did not choose this action. How does the additional information from the National Tree Benefit Calculator about the benefit that trees provide influence your decision about whether and how many trees you would pledge to plant? Which benefits did you find the most compelling? Explain your thinking.
7. How many trees of the size and species you selected for the tree benefit calculation will it take to absorb the carbon dioxide your household releases in a year? Provide details about the tree species and size and show your calculations.