Guest Post! What is your Household Carbon Footprint? And What Can You Do About It?

Today we have a guest post from our friend and fellow Concord resident Jessica Forrest! Jessica has developed tools for companies to measure and reduce their environmental impacts, and has worked with her city of Concord, New Hampshire on carbon footprinting and strategic planning relative to their ambitious 100% renewable energy and emissions reductions goals.  While spending most of the last 6 months trying to keep up with her two boys through the pandemic, she has turned her thoughts to things on the home front.

My city of Concord, New Hampshire recently completed a carbon footprint for the entire community.  The study found that just under half of the city‘s greenhouse gas emissions came from residential use, including gasoline for our vehicles (50%), the fuel used to heat our homes (38%),  and electricity to power our lights and appliances (10%).  The findings emphasized, among other things, the importance of homeowner action for reducing greenhouse gas emissions in our community.

With our city’s Fellow crunching these numbers over the summer, my family of four wanted to find new ways to reduce our own household emissions, but we didn’t know where to start.  So, we decided to calculate our household carbon footprint for one year of our Concord, New Hampshire lives.  Here, I’ll tell you about how we went about it, and what we found.

The Tool

There are many carbon footprinting tools available online, including those from Carbon Footprint, The Nature Conservancy and the Environmental Protection Agency (EPA).  My family and I selected that from Carbon Footprint for ease of use, flexibility, and ability to save results.  This tool also allowed us to easily run scenarios to determine the effect of specific lifestyle changes (such as reducing our household meat consumption, or adding one cross-country flight per year)  on our overall carbon footprint.  We chose June 2019 to May 2020 as the baseline year for electricity and heat, and 2019 as the baseline for transportation, since the COVID-19 pandemic had clear impact on our transportation use.  We pulled out our electricity and natural gas bills, which indicate the amount of kilowatt-hours (kwH) and therms we used over the course of one year.

The Results

Needless to say, my family was surprised by the results! Our family burned nearly 45 metric tons of carbon dioxide equivalents (CO2e) in 2019 to support our lifestyle, equivalent to the weight of 45 small cars. This is just about average for an American family of four.  Of this, 11.5 metric tons CO2e came from the fuel used to heat our home, power our two cars, and turn on our electric appliances.  Other major sources of emissions included that annual flight my family likes to take for vacation (releasing 4.8 tons CO2e) and our food consumption (which released 10.5 tons CO2e).  Other sources included the manufacturing of the things we buy and own such as our clothes, computers, and family cars, and our consumption of other tangible and nontangible goods that nonetheless have impact along their supply chain.  These secondary, or indirect emissions sources contributed a whopping 18 metric tons CO2e to our family footprint.

Figure 1. Our total household carbon footprint.The sources of emissions that we have the most control over – fuel, flights, and food – are shown in color.   Fuel and flights are considered direct emissions sources, while food consumption is an indirect source with emissions throughout the supply chain.  Additional indirect or secondary emissions are shown in grey.  The emissions estimated from our fuel consumption and flights are most accurate to our lifestyle.  The emissions estimated from secondary sources such as food consumption, manufactured items, activities, home and insurance, and education are less customized, based on general assumptions on average supply chain emissions (CO2e/$) from consumption of these goods and services (Carbon Footprint 2020, DEFRA 2012).  

Electricity A surprise for us was that we had expected our electricity usage to be a large driver of our annual emissions – in fact, it comprised only 10% of our fuel-related emissions (or 1.21 CO2e), and an even smaller portion of our total carbon footprint.  One reason for this is that Northern New England’s energy mix is already somewhat clean compared with typical heating and transportation fuels, comprised of 30% nuclear and 20% renewable. The remaining 50% of the electricity energy mix is natural gas, coal and oil.  At this point, all but three of New England’s remaining coal plants have been phased out – but two of these remain in New Hampshire – degrading our air quality in addition to producing emissions! Importantly, the Carbon Footprint calculator enables you to enter New England’s conversion factor for electricity to represent our unique grid energy mix.*

My household’s electricity-based emissions were reduced somewhat by measures we had already taken  to improve energy efficiency, such as replacing worn out appliances with EPA Energy Star alternatives,  replacing incandescent light bulbs with LED’s, and refraining from using our electric heat fixtures and air conditioners when possible.  We decided to further reduce our electricity-based emissions moving forward by switching to a competitive electricity provider that was building new wind power in New England.  A list of such providers is available from the Public Utility Commission and Unitil (be sure to select one that provides renewable power).  Another popular option is to install solar power to eliminate your electricity bill completely!

Heating Fuel

The largest perpetrator of our carbon emissions was the natural gas used to heat our home and cook with.  These sources contributed 60% of our household fuel related carbon emissions!  This is a tough one for us, as we have an old home and we live in New England where winters are cold!  We had already undertaken the process of weatherizing our home in 2012 with assistance from NH Saves, replacing our old boiler and hot water tank with the most efficient natural gas versions available at the time, replacing old windows, and reducing our thermostat a couple degrees in winter.  These steps had already reduced our energy use and natural gas bill substantially.  However, we clearly have a lot more to do to phase out our use of natural gas!  Next steps include using less hot water in our shower and washer, further weatherizing the remaining leaky areas of our home, replacing our cooking stove and gas fireplace with electric alternatives, and installing air source heat pumps and solar hot water.  This process is going to take some time!

Transportation

Another huge emissions source for my family are our cars, contributing 30% of our fuel related emissions.  We already drive one hybrid car, using this car for longer trips and commutes.  We use a small All-Wheel Drive car around town and on snowy days.  This result shows that we need to redouble our efforts to drive less and carpool, bike and walk more.  Eventually, we plan to replace our existing cars with electric vehicles (EVs), which are becoming more available and affordable each year.  In fact, some economies plan to ban the sale of gasoline vehicles entirely.  So, we need to get with the program and buy EV’s!

Other Emissions Sources

Other common sources of household emissions included air travel, food, and material good consumption.  If we cut out that annual family air trip per year and stay local, we would knock 4.8 CO2e metric tons (>10%) off our total carbon footprint, more than our total gasoline emissions from driving for an entire year!  Food made up over 20% of our total carbon footprint!  Indeed, our family members eat meat – but becoming vegetarian would reduce our food-related emissions by 5 metric tons CO2e annually (that’s 5 cars worth in weight)!  Buying local and minimally packaged food where possible also helps to decrease food transportation and manufacturing emissions.In most American households, the purchase of manufactured items such as clothes, cars and furniture contributes more than 10% of the average U.S. carbon footprint.  Reducing this element includes buying only what we really need, buying used, and buying local.  Other strategies my family identified moving forward to reduce our secondary emissions include divesting from fossil fuels, planting trees, and offsetting our carbon footprints by investing in renewable energy infrastructure, energy efficiency, and forest conservation and reforestation projects around the world.

Moving Forward

Completing this household carbon footprint gave us some real data about our biggest emissions sources, and tangible strategies for reducing our emissions.  Scientists warn that to avoid the worst effects of climate change, global emissions need to be reduced by 45% by 2030 compared with 2010 levels. By 2050, we need to move towards <2 metric tons GHG emissions per person per yearIf we adopt the 2030 global target for our household, we will need to reduce our most direct and measurable emissions (from fuel, flights and food) from 27 to 15 metric tons CO2e by 2030.  Beyond the consumer choices that we have at the moment, reducing our direct and indirect emissions substantially can be best accomplished with collective action (beyond our household) and company or political leadership that make more reduced and zero net carbon options and technologies available.

My advisor used to tell me that “you can’t change what you can’t measure.”  I tend to agree that measuring certainly helps us to make the best and most efficient decisions.  Now that our household measurements are done (for now), we have some hard work ahead.  Check back with us next year as we recalculate our footprint and see how we are doing!

*In the Carbon Footprint tool, I accounted for the specifics of Northern New England’s energy mix by using the conversion factor of 0.2671 kg CO2e/kwH.  This was calculated by using the northern New England (NEWE) conversion factor of 0.56372 lbs CO2e/kwH increased by the by the grid loss factor of 4.49% and converted to kilograms) (USEPA eGrid 2018).  If not in New England, you can get your electricity conversion factor from your utility.

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