Carbon Footprint Analysis

Today’s post is focuses on a the carbon footprint calculation presented by the World Resources Institute (WRI) and features an analysis of carbon footprints for two households.

A carbon footprint measurement is the amount of greenhouse gases released by, in the case of this project, a household. Of course, a carbon footprint can be measured for an individual or a larger body of people, such as a company, municipality, or an entire nation as well. In this way the measurement is effective in determining an entity's contribution to global warming. Carbon dioxide is not the only greenhouse gas, and the WRI takes this into account by converting other greenhouses gases used into a carbon equivalent in terms of “global warming potential.” The specific unit being used in the calculation is pounds of carbon dioxide per month.

The carbon footprint calculation from the WRI combines driving habits and the amount of electricity, natural gas, heating oil, and propane utilized by the individual or group. However, a true carbon footprint would also account for all the energy used to create and maintain all the products that a person or organization uses. Since transportation and home power usage constitute approximately 40% of all energy used by an average American, this “true” carbon footprint would be 2.5 times the value given by the calculation from the World Resources Institute. For the purposes of the blog, however, I will only be using the original footprint value calculated.

Determining Carbon Footprints of Two Houses

I took carbon footprint data from my house in Kalamazoo and from my Aunt Ginger’s home in Interlochen, MI. I choose her home for comparison because I wanted to see if there were emission differences based on rural and urban settings. Specifically, my aunt, living in a rural village, must commute to work in a larger town and must drive farther for standard day-to-day tasks because of rural dispersal of resources. Furthermore, I wanted to see if there was increased energy use at a home in a slightly cooler climate like the northwest Lower Peninsula of Michigan (where Interlochen is located) compared to southwest Michigan.

It should be noted that because I've only lived in the Kalamazoo house since house since mid-August, I'm collecting data for the two homes between September 2010 and and March 2011 only. Accordingly, data will predominately reflect patterns of winter energy use. Once this data was collected I produced a monthly average rate for electric energy and natural gas use. Transportation figures were averaged on a weekly basis. Also please take not that both houses use natural gas for room and water heating.

My House, Kalamazoo, MI

3 residents

Car1: 60mi/week, 23mpg

Car2: 18mi/week, 22mpg

Car3: 70mi/week, 26mpg

277.57 KWh/month

6.65 mcf natural gas

1835lbs carbon dioxide per month (below national average)

72% Home Energy, 28% Transportation Energy

Interlochen, MI

2 residents

150mi/week transportation, 13mpg

446.71 KWh/month

5.97 mcf natural gas

2472lbs carbon dioxide per month (approximately at national average)

60% Home Energy, 40% Transportation Energy

I think it is very clear that my aunt's transportation played a major factor in her increased carbon footprint. She traveled farther and with far worse gas mileage. This makes sense as she has a large pick-up truck and must travel into Traverse City for work at her office (a drive of about 12.5 miles). What I can not ascertain, however, is how my aunt's home used so much more electricity than mine. Perhaps this energy went to a dishwater and a washer and drier for clothing? My house does not have such equipment and her home does. This is a possibility, but I can not be certain.

I believe that my greater rate of natural gas use can be attributed to two major factors. First of all, there is an extra person in the Kalamazoo house, meaning extra showers that use extra natural gas to heat water. This heating use would probably add up fairly quickly. Second, the windows in my home let out significant amounts of heat, so more natural gas must be used to maintain the comfortable temperature. My original conjecture that a house farther north would require more heating from natural gas seems to be proven false by this test, but of course a complete analysis of that hypothesis would require a study of more than two homes.

I am happy to be able to say that my home was below the national average for carbon footprint. What makes this most impressive is that this level was obtained during a period dominated by the winter months, which are extremely energy intensive because of heating requirements. My home does not have air conditioning, so energy use in the summer months would most likely not rise significantly.

However, there is always room for improvement, and being below the United States' average of carbon emissions still makes me a large polluter from a global perspective. For example, I should absolutely apply energy-efficient plastic around my windows to prevent heat loss. Furthermore, although my aunt is not above the national average, she really should invest in a car with better gas mileage. Even those who are not the major contributors to the problem must help to alleviate it. As always, we're in this together.