Commons' Guide to Carbon Footprint Tracking

Fossil fuels are a big source of greenhouse gas emissions, but they’re not the only source. Emissions also come from our land use and waste systems. The products, services, and energy that we use rely on these emissions-generating processes at every step — from manufacturing to disposal. These greenhouse gases are heating up our planet and causing the global climate crisis. Your carbon footprint is an estimation of all the emissions that come from the products, services, and energy that you use.

Reclaiming our carbon footprints 

The carbon footprint concept draws a lot of speculation because of its troublesome history. The concept was originally developed at the University of British Columbia to calculate the demands on an ecosystem and monitor resources. Decades later, it was co-opted by Big Oil as a way to divert climate responsibility onto individuals. The irony is that Big Oil companies are manufacturing the leading cause of the climate crisis — fossil fuels. 

It’s time to reclaim our carbon footprints and use them the way they were first intended — as a metric to help us understand our biggest opportunities for impact.  

Measuring the emissions of everything we buy

The Commons app is a free, easy tool that automatically estimates the emissions of your purchases to calculate your carbon footprint. Having a carbon footprint is not inherently a bad thing. We all have different factors that affect our carbon footprints, and discovering those factors can help us make more intentional choices. 

Commons combines unique information about your lifestyle and your spending history with third-party datasets to give you a personalized carbon footprint and a real-time feed of your emissions. These insights can help you prioritize your choices so you can make the most impact.

Here's how to start tracking your carbon emissions:

  1. Download the app, then take the 3-minute Carbon Survey to get a high-level estimate of your emissions based on where you live and your lifestyle habits. 
  2. Then, securely link your credit and debit cards to personalize and refine your carbon footprint in real-time, based on each of your transactions.

We take privacy seriously. You own your data and we don’t see or store sensitive information about you or your finances. We don’t share your data without your consent, and we never sell your data. Tracking your carbon emissions is free, and always will be.

Download the app to get started → 

How Commons Calculates Your Carbon Footprint

To convert each transaction from its financial currency (money) into the Earth's currency (carbon), Commons’ team of data scientists and carbon analysts use rigorous methodologies from academia, governments, and other trusted sources, along with national and local datasets from 180 purchase categories.

Here's a simplified example. If you buy a chair at IKEA for $50, Commons multiplies the dollar value of this transaction by the average carbon intensity (in kg CO2e per dollar) of a furniture purchase.

Commons carbon footprint calculation

Some types of purchases are straightforward like this. Others may factor in information from your Carbon Survey. For example, your location is a factor for determining the cost of gas which makes your gasoline emissions more accurate. Or the frequency that you eat meat will be considered when calculating emissions for your food purchases. Commons' algorithm is made up of three key data sources: (1) user-inputted information, (2) real-time, automated spending data, and (3) rigorous third-party data sets.

1. User-inputted information

Not all parts of your carbon footprint can be calculated with spending data alone. Some lifestyle factors like dietary preferences and where you live will impact the carbon footprint of your purchases in more personalized ways. Other types of purchases might be too ambiguous to discern from transaction data alone.

To create a personalized footprint, Commons asks users to provide answers to questions about diet, lifestyle, and home through our Carbon Survey, which most users complete as part of their app onboarding process. By combining insights from these answers with additional external datasets, such as those from Oxford University and the US EIA, Commons is able to fill in the gaps to create a more complete estimate of your total carbon footprint.

2. Automated spending data

Commons uses the Plaid API, a secure financial tech platform, to connect your bank account(s), and evaluate information about your purchases. Plaid is trusted by leading financial apps like Venmo, Robinhood, and Mint to securely process bank-related information. Commons doesn’t store any sensitive information about accounts, but rather evaluates the names, categories, and amounts of your transactions.

When you connect your card(s) to Commons using Plaid, we cannot (and will not) charge your account, withdraw or transfer money, or create a transaction on the account in any way. We take your data privacy and security very seriously, and never sell your data.

Read our full privacy policy → 

3. Third-party data sets

Commons uses a rigorous, national-level dataset from the United States Environmental Protection Agency (EPA) called the US Environmentally-Extended Input-Output (US EEIO) model. The EEIO combines macroeconomic data with National Greenhouse Gas Inventories to provide a per-dollar estimate of carbon emissions from 405 US industry sectors. These estimates include carbon impacts starting at the beginning of the supply chain (i.e. raw material extraction) up through to the manufacturer’s gate.

We applied additional research from Yale University to extend these climate impacts to the customer point-of-purchase, creating a unique, proprietary mapping between financial transaction categories and USEEIO's environmental industry sectors. With this mapping, we have carefully crafted carbon weights for each transaction category to provide our community with improved, granular estimates of the carbon impacts of their purchases.

Read more about how Commons calculates carbon footprints → 

Building a carbon intuition

Measuring the emissions of everything you buy helps you cultivate an intuition for where carbon emissions are embedded in the supply chains and power sources we rely on. When you understand the carbon emissions of a cross-country flight versus a beef burger, you can start to assign a climate value to your purchases and actions using the Earth’s currency, carbon. As you build your carbon intuition, you can better understand where to focus your efforts and how to reduce emissions.


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Commons team hiking
Thrive Market
Wholesaler of healthy food from leading organic brands
Commons Team
March 6, 2023
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