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Lexi Zimmerman: My Journey Towards Carbon Neutrality

13 December 2015 – At the beginning of 2015, I decided to start tracking my CO2e emissions. I was interested in quantifying the effects of my lifestyle.

Lexi Zimmerman“I am only one; but still I am one. I cannot do everything; but still I can do something; and because I cannot do everything, I will not refuse to do the something that I can do.”

Edward Everett Hale

I started this year with the goal of measuring and analszing my carbon emissions, with a gameplan to start making behavioral changes in 2016. Instead, I found myself cycling through the iterative process below. This process lead to several additional goals goals (numbers 3–6 below) and an interesting whirlwind of personal experiments in sustainable living.

Goals for 2015

  1. Develop a methodology to collect data and measure my CO2e emissions.
  2. Analyse my first year of carbon tracking.
  3. Install a Nest thermostat; quantify savings in energy, cost, and carbon emissions.
  4. Purchase renewable energy equivalent to 100 per cent of the electricity in my home.
  5. Experiment with making sustainability a top priority in my decision-making for finance, clothing, transportation, and products.
  6. Purchase carbon offsets equal to the emissions that I cannot eliminate.

Goal 1: Develop a methodology to collect data and measure my CO2 emissions

Putting in place a robust personal data collection and management system for my carbon tracking was an intricate process. I had a definitive leg up because I spend a large portion of my professional time facilitating this process for client implementations. First up on the agenda was identifying the various consumption streams I would be measuring.

I decided to look at the use and cost for the following:

  • Home energy – Natural Gas – (therms from my energy bill)
  • Home energyElectricity(kWh from my energy bill)
  • Car travelpersonal (gallons of gas used)
  • Car travelUber (miles traveled)
  • Air traveldomestic (passenger miles traveled)
  • Air travelinternational (passenger miles traveled)
  • Public transit travel train (passenger miles traveled)
  • Hotel stay(days)

I also measured heating degree days, cooling degree days and average daily temperature for weather normalization in my energy use data crunching.

I spent the first few months iteratively building my personal system. I say iterative because it went through several cycles of revisions in terms of:

  • Data collection methodology (e.g. do I want to use my bill dates from my energy bills or do I want to collect monthly?)
  • Indicator Structure (e.g. building out a reporting hierarchy so I could view breakdowns easily)
  • Emission factor methodology (e.g. Would I apply radiative forcing to air travel? There is more about in a previous blog post I wrote here.)

It was very challenging choosing which emission factors to use, primarily because this is the all-important conversion factor from consumption to emissions. Some of the variances between factor sets for the same consumption stream were very large, which lead to very different end numbers in my final CO2e emissions. For example with my personal car use emission factor, I opted to include the indirect emissions and the construction/ manufacturing over the lifetime of the car. This yielded a final emission factor of 11.69 kg CO2e/gallon as opposed to the original 8.78 kg CO2e/gallon published by EPA Climate Leaders. (More about that methodology here.)

Goal 2: Analyse my first year of carbon tracking

I released 19.7 metric tons of Co2e throughout the year. What does that actually mean?

Carbon dioxide equivalent (CO2e) is a standard unit for measuring carbon footprints. The general idea is to express the impact of CH4 and N2O in terms of the amount of CO2 that would create the same amount of warming. The factor sets I sourced from use the IPCC SAR and AR4 Global Warming potentials values.

19.7 metric tons of carbon dioxide equivalent is equal to 10,696 m3 or 3,77,700 ft3 or 2,352,620 gallons.
It might be easier to picture my total annual emissions as filling a 13.8 foot deep football field or 3.6 Olympic sized swimming pools. Yowza!

How do I compare to the global and American average?

Lexi = 19.7 tons of CO2e in 2015
Global average = about 4 tons of CO2e per year
North American average = 20 tons of CO2e each year

What is the breakdown of those 19.7 Metric tons I emitted?

overall pie

  • 40 per cent of my total emissions were from two international trips to London and Qatar.
  • 20 per cent were from five US trips (Tampa, Denver, San Fran, NY, Houston).
  • Uber, hotel, and train combined accounted for less then 1 per cent of my overall emissions

Key learning

Together these finding help me quantify and compare which decisions and actions are the most impactful, i.e. aggressively changing my pattern of use and eliminating Uber trips, hotel stay, and public transit would have a maximum overall effect of .17 metric tons of CO2e (less than 1 per cent of my total emissions) as opposed to not taking my trip to Qatar would lessen my CO2 emissions this year by 4 metric tons or 21 per cent.

What was my trend over time?

monthly breakdown

  • Again, the huge spikes are air travel
  • My highest month was April with 5.74 metric tons of CO2e released (primarily due to my international flight to Qatar and a business trip to New York)
  • My lowest month was August with .21 metric tons of CO2e released (.15 from car travel, .05 from natural gas, and .01 from Uber travel)

What does the trend look like if you remove air travel?

monthly less air

  • Downward trend
  • You can see the seasonal variability starting to come back into play as the Chicago winter sets in later in the year
  • Check out goal 4 below for why the dark blue bar for electricity emissions disappears in July

How did the temperature and heating degree days affect my energy use?

temp nat gas

Obvously when it was colder my natural gas/ heat use went up. (Don't need regression analysis to prove that one.) I did get a feel for my min and max use which was interesting.

Base electricity use: October – 16.54 therms (484.62 kWh)
Base natural gas use: November – 7.94 therms (232.65 kWh)
Highest month of electricity use: January – 31.01 therms (908.53 kWh)
Highest month of natural gas use: January – 165.18 therms (4,839.79 kWh)

Goal 3: Install Nest thermostat and quantify savings in energy, cost, and carbon emissions

I was excited to receive a Nest smart thermostat for my birthday this year. The below figures are from a 8-month analysis from May–December comparing my electricity cost last year to this year. It paid for itself in 7 months which was nice. That carried a lot of weight for several friends debating buying one. Also, the fact that you can take it with you if you move was a deal-maker for some folks.


Cost savings: $ 231.74 (original cost was $220.00)
Energy use avoided: 2,485.20 kWh
CO2e avoided: 1.70 Tons

Goal 4: Purchase renewable energy equivalent to 100 per cent of the electricity in my home

In July 2015 I started "sourcing" my home's electricity from 100 per cent renewable sources (primarily wind) through Arcadia Energy. I still use my local utility company, Comed, for the physical poles and wires but Arcadia purchases renewable energy credits (RECs) equal to my electric bill on my behalf.

A REC is a claim on the social, environmental, and other non-power related attributes of electricity produced by renewable sources. Buying RECs is a direct financial investment to renewable projects, helping them to grow and represent more of our power generation. By purchasing RECs, combined with an equal amount of electricity, you are using clean energy.

I used 2,143 kWh of clean energy which is equivalent (somehow) to planting 38 trees (How Arcadia derived the tree stat is a mystery, but thought I would include it because it sure does sound nice).

I highly recommend using Arcadia as the whole process was really easy to setup and I am now supporting renewable energy without ongoing effort. If you are a data nerd, they also have a really nice UI and data dashboards. Check out Arcadia's how it works page and FAQ page for more information.

Goal 5: Experiment with making sustainability a top priority in my decision-making for a choice in the following areas: products, clothing, finance, and transportation

Products: biodegradeable trash bags

Fail. This was frustrating because they didn’t work nearly as well as regular trash bags. They broke more easily and they used twisty ties as opposed to having a drawstring top. They had a nice lemon scent but the fact that they broke so easily drove my crewmate (cousin/roommate) nuts.

Clothing: 333 clothing challenge

Success! This was equal parts experimenting in minimalism as well as sustainability. The basic premise is you pick 33 items of clothing as your entire wardrobe for one season (3 months). I really enjoyed this challenge. Aside from the obvious benefits of lower cost, less stress over picking outfits there was also an interesting culture of camaraderie that developed among folks in my friend/work circle. I started the challenge with one friend and picked up two more curious participants before the end. More info here.

Finance: GreenChoice Bank

Fail. I was very excited to switch my banking over to the first B Corp certified bank, which just happened to be in Chicago and 10 miles away. That was until I went to do some online banking in July and instead of seeing the login screen there was a new landing page informing me that the bank had failed and the FDIC (Federal Deposit Insurance Corporation) had taken over. Talk about a quick way to up your adrenaline and cortisol levels. All fine now, but frustrating none-the-less.

Transportation: biking as my primary form of transportation

Success! Last year I biked 200 miles in three days for climate change awareness. This was an eye opening experience that made me realise I could and should be biking quite a bit more than I do. It’s healthier, cheaper, and often quicker in the city. This year I decided to make biking my primary form of transportation followed by public transport and then my car. I bought an odometer and for 100 days from October–December I biked 175 miles. A large portion of that is the 3 mile commute to and from work, but I also biked to beach volleyball and friends houses regularly. There was even one brave Saturday where Nick and I woke up at 6am and biked the 40 miles to my parents house in the suburbs… and then promptly napped for several hours.

Goal 6: Purchase carbon offsets equal to the emissions I have not yet managed to eliminate

For my emission from H1 I purchased REDD (Reduced Emissions from Deforestation and Degradation) Credits through I Stand for Trees. (I wrote up my experience with offsets here.) I still need to do more research around how best to offset my remaining H2 2015 emissions.

Some possible avenues I will research include:

  • Afforestation / Reforestation (A/R)
  • Improved Forest Management (IFM)
  • Reduced Emissions from Deforestation and Degradation (REDD)
  • Wetland Restoration
  • Fertiliser Management
  • Avoided Conversion of Grasslands & Rangelands
  • Rice Production
  • Livestock Waste Management
  • Improved Cookstoves
  • Water Purification
  • Destruction of Ozone Depleting Substances (ODS)
  • Fugitive Methane Emissions: Transport / Fleet Efficiency

In conclusion...

I thought I should write an "in conclusion" paragraph to neatly sum up everything I learned and what my plan is moving forward. Truly though, living sustainably is an ongoing, somewhat messy, experiment that doesn't have a neat conclusion. It does, however, have an ethos that I think is captured by the Edward Everett Hale quote that I opened this post with....

“I am only one; but still I am one. I cannot do everything; but still I can do something; and because I cannot do everything, I will not refuse to do the something that I can do.”

Every time I read that quote I can't help but feel very inspired and simultaneously very small. No one can do everything but everyone can do something. Internalizing and acting from this strange juxtaposition of empowered and insignificant has been quite an adventure that I will continue to pursue.... On that note, I suppose it's time to brainstorm some goals for 2016! :)

Here we go... Stay humble. Stay hungry.

Read more on Lexi's blog.


17 January 2018, 16.00-17.00

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2018 intake workshop dates

Workshop 1: 16–22 September 2018 
Workshop 2: 31 March–6 April 2019
Workshop 3: 1–7 September 2019   
Workshop 4: 29 March–4 April 2020

2017 intake Workshop dates

Workshop 1: 2–8 September 2017
Workshop 2: 8–14 April 2018
Workshop 3: 2–8 September 2018   
Workshop 4: 31 March–6 April 2019

2016 intake Workshop dates

Workshop 1: 18–24 September 2016
Workshop 2: 26 March–1 April 2017
Workshop 3: 30 July–5 August 2017
Workshop 4: 8–14 April 2018