Calculating your carbon emissions from electricity use

August 22, 2023

Why you should track this scope 2 emission.

Black and white photo of a power panel on top of purple abstract lights to signify how to calculate your CO2 emissions from electricity use
Infographic: How to calculate emissions from electricity

Did you know that, according to the U.S. Department of Energy, buildings account for over 76% of electricity use? (And only about 20% of electricity comes from renewable sources, a big issue when it comes to climate change.) It tends to be an obvious starting point when calculating your greenhouse gas emissions and carbon footprint because electricity is relatively easy to measure—and just about everyone uses it.

But why would you measure your energy use? It helps you set efficiency targets, cut costs, and reduce your impact on the environment, for starters. One level deeper, measuring how much electricity your organization uses helps you spot trends and identify equipment that consumes large amounts of energy so you can make environmentally friendly adjustments.

Electricity produces varying degrees of greenhouse gas emissions

Unless your business is completely off the grid or uses 100% renewable energy (kudos if you do!), you indirectly create GHG emissions from electricity generation. But the amount of emissions depends on more than just how much energy you use. It also comes down to how your electricity is produced and distributed from the power plant, meaning the breakdown of fuel types your utility provider uses to make electricity. Most electricity in the U.S. (63%) is made from a mix of fossil fuels like natural gas, petroleum, and coal, followed by nuclear (20%), with some sources supplemented with renewables like wind, solar, or hydro. The more your electricity provider relies on fossil fuel combustion to generate electricity, the more indirect emissions you create.

What emissions scope is purchased electricity?

If you’re going to measure your electricity emissions, you should know what emissions scope it falls under. Why? Because emissions scopes help you understand your emitting behaviors and your level of control over these sources.

Purchased electricity is scope 2, meaning it’s an indirect emission because while you buy the electricity, it’s produced elsewhere, where you have limited control over the mix of fuel consumption. Think of these as indirect emissions you create by figuratively (and literally) keeping the lights on. Your purchased electricity also powers some not-so-obvious stuff like your building’s central air or cooling systems, heaters, machinery, computers, on-site servers, other office equipment, and so much more. While you can reduce your consumption and associated emissions with intentional behavior changes like using efficient equipment and appliances or opting for natural daylight instead of electric lighting, the actual generation of the electricity is outside of your direct control.  

Don’t know about emissions scopes? Check out our emissions scope explainer video.

What is needed to calculate electricity emissions?

Electricity generally gets reported in kilowatt-hours (kWh) or multiples of kWh and you can calculate your emissions data from kWh pretty easily. You can get your electricity usage from your monthly bills, whether you access your account online or still receive paper bills. Many electricity companies offer a detailed view of daily usage, too.  

To give you more detail on how carbon footprint is calculated, your total electricity consumption in kWh is then multiplied by an emissions factor (EF) associated with the type of energy source you use and the activity rate (A) or the time in production emissions are put off. Then, multiplying that by any emissions reduction (ER) that is taking place or is to be expected, you can get your effective emissions output (E). According to the EPA, the equation is as such:

E = A x EF x (1-ER/100) 

E = emissions, A = activity rate, EF = emission factor, and ER = overall emission reduction efficiency, in a percentage

To get a more precise estimate, you can use an energy audit software with a purchased electricity emissions calculator to measure your energy consumption more accurately. With Sustain.Life, you can input all of the details about each building or location using monthly energy bills and its estimated energy consumption, and it will calculate your carbon footprint in metric tons (MT) of carbon dioxide equivalent (CO2e). This can help you identify where you are using the most electricity and how to reduce your emissions from electricity use. 

If you can’t get your kWh, we can estimate your emissions based on national averages and your facility type, square footage, and ZIP Code. This helps us determine where your power is produced from, thus getting an understanding if it is from coal, natural gas, oil or hopefully more renewable resources. So where you locate businesses could also be something to consider.

Image of powerlines in the shadow with pink clouds in the background. Links to watch the webinar: "Calculating electricity emissions using location- and market-based methods"

Discover how much electricity you use

Find out if your organization buys electricity directly, or if a property owner or manager buys your electricity, ask them for the data. If you’re in a multi-tenant building, find out if your space is sub-metered. As a last resort, ask if your building can provide a pro-rata share of your energy consumption, inclusive of your share of common areas like cafeterias, fitness facilities, and corridors. Don’t forget to think about each property at your organization—offices, manufacturing sites, retail spaces, warehouses, storage facilities, parking lots, and so on.

You’ll want to calculate your emissions monthly for tracking purposes unless your business depends heavily on electricity use (e.g., commercial real estate management, data center operation).  

Automatically calculate emissions from your electricity

Get access to a full suite of other carbon footprint calculators to measure and manage your GHG emissions.

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What’s next?

After measuring your purchased electricity, it’s time to start thinking about reduction strategies. You’ll want to look for equipment that you can power down when not in use—think computers and other office equipment that pull phantom power—and other efficiency upgrades like switching to ENERGY STAR-rated equipment.  

Beyond that, you can purchase off-site renewable energy or renewable energy certificates (RECs) and start laying the groundwork to see if on-site renewable energy systems are a possibility for you.  

And if you need help doing any of those, Sustain.Life’s carbon accounting platform includes over 100 step-by-step guides to help reduce your company’s emissions.

How to choose the best carbon accounting methods.


1. EIA, “Electricity explained,”,were%3B%20natural%20gas%2038%25%3B%20coal%2023%25%3B%20nuclear%2020%25 Accessed March 30, 2023

2. EPA, “Introduction to emissions factors,” Accessed March 30, 2023

Editorial statement
At Sustain.Life, our goal is to provide the most up-to-date, objective, and research-based information to help readers make informed decisions. Written by practitioners and experts, articles are grounded in research and experience-based practices. All information has been fact-checked and reviewed by our team of sustainability professionals to ensure content is accurate and aligns with current industry standards. Articles contain trusted third-party sources that are either directly linked to the text or listed at the bottom to take readers directly to the source.
Sustain.Life Team
Sustain.Life’s teams of sustainability practitioners and experts often collaborate on articles, videos, and other content.
Alyssa Rade
Alyssa Rade is the chief sustainability officer at Sustain.Life. She has over ten years of corporate sustainability experience and guides Sustain.Life’s platform features.
The takeaway

What to include: Electricity your organization uses for its general operations.

Why measure: The first step is to understand your electricity use and its associated GHG emissions. After you know how much you use, you’ll better understand what reduction strategies are most effective for you.

Emissions scope: Scope 2

How often: Monthly, unless you depend heavily on electricity use (for example, if you’re in commercial real estate management or operate a data center).

What to do next: Start measuring with Sustain.Life’s carbon calculator. Then, integrate renewable energy sources into your energy mix and other strategies to improve the energy efficiency of powered equipment.