The Community Carbon Footprint
Every journey toward net zero begins with understanding where you are today. For a senior living community, this means taking stock of the greenhouse gas emissions that come from daily operations such as heating and cooling buildings, transportation, dining services, and waste.
Together, these sources make up your community’s carbon footprint.
Calculating a carbon footprint provides a clear starting point, or baseline, against which future progress can be measured. Just as residents and administrators rely on budgets to guide financial decisions, a carbon footprint serves as a guide for sustainability planning. It highlights the areas where emissions are highest, allowing communities to focus their efforts where they will have the greatest impact. With this knowledge in hand, your community can set realistic goals, track improvements, and move step by step along the pathway to net zero.
What is a carbon footprint? In short, it is a number. That number represents the tons of greenhouse gas (GHG) emissions produced by your community each year. If the ultimate goal is to bring that number down to zero, the first step is to know what your number is now.
As a resident volunteer, you will likely need some cooperation from your administration. Consider who can help you gather utility bills for a base year (more on this later), and who, perhaps even you, is best suited to enter the data into a carbon footprint calculator.
DIY Carbon Footprint or Contractor?
In some cases, communities choose to hire a contractor to conduct a professional GHG or energy audit. Such audits often include preparation of a comprehensive carbon footprint.
That said, a footprint does not need to wait for outside help. A community can develop a basic version on its own before deciding whether to bring in a contractor, or it can wait and have the footprint completed as part of the audit. Either approach is valid and depends on the resources and timing of the community.
Because each senior living community manages utilities differently, the path to that number can vary. Some campuses have a single master utility account, others have residents billed directly, and many operate with a combination of common-area bills and individual metering. These differences make it especially important to be clear about what is included in your calculations.
Before asking for utility bills or recruiting volunteers, it is important to understand the concept of Scopes. Not all carbon footprints are measured in the same way, so comparing results across communities can be tricky.
A thought experiment:
- Community A reports a carbon footprint of 4,000 tons of GHG emissions per year. Their calculation included on-site energy use, purchased energy from off-site, and even employee commuting habits.
- Community B reports a footprint of 1,000 tons. However, their calculation was based only on electric bills.
At first glance, it looks like Community B is ‘greener’ than Community A. In reality, the two numbers cannot be compared fairly because they were measured using different scopes. This difference highlights the importance of deciding what your community will include when determining a carbon footprint. It is equally important to clearly state what has been measured in order to maintain transparency.
What Should be Measured and How?
To get a handle on what should be measured, and to ensure comparisons are meaningful, we need to talk about both the types of greenhouse gases and the categories, or scopes, in which they are reported.
Carbon dioxide is the most common greenhouse gas, but it is not the only one. Other gases, such as methane and nitrous oxide, also cause atmospheric warming, each with its own level of potency. To simplify this complexity, the Greenhouse Gas Protocol converts the warming impact of all greenhouse gases into an equivalent amount of carbon dioxide, called CO₂e. This common unit makes it possible to report a single number that represents a community’s total emissions. The total amount of CO₂e a community produces in a year is known as its carbon footprint, measured in tons.
Other greenhouse gases besides CO2
Our burning of fossil fuels has created atmospheric CO2 levels far higher than those of any time in the past. CO2 is estimated to be responsible for 75% of global warming. The remaining 25% comes from other greenhouse gases described below.
The global warming potential (GWP) is a metric used to compare the warming impact of different greenhouse gases. They need to be measured over the same time period because each gas stays in the atmosphere for a different length of time and absorbs heat at different rates. A 100-year time period is frequently used and we will follow that convention. By definition, CO2 has a GWP of one.
To compare the contribution to global warming of each GHG we need to consider both the GWP and the atmospheric concentration of that GHG.
Here are some other greenhouse gases to be aware of:
- Methane: Methane (CH4) is the primary component of the natural gas we mine, transport, and burn. It is also produced by cattle, and large quantities are released as permafrost melts. It has a GWP of 28 and at current emission rates, methane is estimated to cause around 15% of global warming.
- Nitrous oxide: N2O is produced by combustion of fossil fuels and by agricultural application of fertilizer. Its 100 yr GWP is 265. It is estimated to be causing around 6% of global warming.
- Fluorinated refrigerants: Some common refrigerants are powerful greenhouse gases. For example, freon (R12) has a 100 yr GWP of 10,900! During normal use, refrigeration equipment will not normally leak these gases. But at end of life, the equipment must be properly disposed of, or these gases will gradually escape into the atmosphere. These refrigerants and other fluorinated gases are currently estimated to be producing about 3% of global warming.
All greenhouse emissions caused by human activity will need to be eliminated or technology that can sequester any remaining humanly caused emissions must be developed and deployed if our goal of net zero emissions by 2050 is to be met.
For more information:
Once we know what gases are being counted, the next step is to see where those emissions come from. To help with this, the Greenhouse Gas Protocol divides emissions into three groups: Scope 1, Scope 2, and Scope 3. These groups set the boundaries of what is included in a carbon footprint and make it easier to compare one community’s results with another.
