Your Carbon Footprint

Have you wondered how to reduce your household carbon footprint? It turns out that it’s not hard to do.

First, start by getting a baseline. What do you use today? There are any number of websites that make this easy for you to calculate. For this example, I’ve used the EPA’s carbon footprint calculator. You’ll need your monthly heat and electricity bills, plus the mileage on your car if you want to do this yourself.

The EPA calculator starts by asking about your household, and how you heat. We’re a two-person household, heat with electricity, and use an average of 1,465 kWh each month. According to the EPA calculator, that equates to 14,890 lbs of CO2e annually. That’s 36.4% higher than the average in our zip code, which is 10,910 lbs. Ouch! The calculator makes some suggestions, like switching to ENERGY STAR lighting and appliances, but we’ve already done many of those things.

Next the calculator ask about driving habits. We have two vehicles. I drive about 10,000 miles annually, and Joanne around 2,500. The calculator also wants to know what the fuel mileage for your vehicle is. If you don’t know it yourself, the Department of Energy maintains a handy site at fueleconomy.gov where you can look it up. The DOE rates my Tesla Model Y at 125 mpg, and Joanne’s Audi at 30 mpg, which equates to another 3,245 lbs of CO2e. That moves us to 18,135 lbs of CO2e annually, but now we’re ahead. The average household in our zip code clocks in at a whopping 31,878 lbs annually! Apparently, they drive big gas guzzling vehicles…

“Wait, wait”, I hear you saying. “Isn’t your Tesla an EV? Why is it rated in mpg?”. Yes, it is. However the DOE rates it at 125 mpg because there is a cost to generating the electricity that powers it. They use a fairly crude measure, which is the amount of gasoline required to deliver the same kWh of energy used by the Tesla to drive a specific distance. More on that in a minute.

The last part of the EPA calculator is to give you credit for recycling. The average two-person household in our area sends waste to the landfill equivalent to 1,383 lbs of CO2e annually. We recycle aluminum, glass and paper but not all plastic, so they give us a credit of 511 lbs, meaning our waste CO2e is reduced to 872 lbs. We’d like to recycle more plastic, but Recology restricts the types we can recycle.

The calculator produces us a report like the one below. It shows our emissions at 19,007 lbs of CO2e annually, primarily from household electricity consumption. Note that I haven’t taken any of the suggested “planned actions”. Most of them, like replacing old appliances and lightbulbs, we’ve already done.

Next, try to reduce your footprint. You could use the EPA calculator suggestions, but as I mentioned above, we’ve already done most of them. Given that the bulk of our CO2e footprint comes from electricity consumption, it makes sense to try and focus on making the electricity we use cleaner. The answer is renewable energy. Alas, we live in a condo and it would require other owners to all agree in order to install solar panels on the roof of our complex. Plus, we live in the Pacific Northwest which has prolonged periods of cloud cover in the winter, which might make solar less efficient. However, it turns out that Puget Sound Energy provides us the option, for an extra $.01/kWh, to buy “Green” energy. This is 95% generated by wind and solar, and 5% from biogas.

So we did this, with dramatic results. It costs us less than $15/mo on the electricity bill, and basically eliminates the CO2e footprint for our home, and for the Tesla. Returning to the EPA calculator, I calculate that we have now reduced our annual household CO2e footprint to just 3,352 lbs. That’s 10% of the average CO2e footprint of similar households in our neighborhood. Sweet!

This method is imperfect. The EPA calculator only calculates household impacts. It doesn’t take into account things like food or air travel, and it uses assumptions about average households that probably will vary somewhat for most individuals. But it’s a good start.

So what’s your household carbon footprint? Grab your utility bills, head over to the EPA website to find out. Can you reduce it? Tell us how you did, below.