How to Calculate the Carbon (CO2) Footprint and Greenhouse Gas (GHG) Emissions of an Office Building

Climate change is influenced by many factors, including greenhouse gas (GHG) emissions from office buildings and businesses. Globally, buildings and offices are responsible for over 40% of the world's energy usage, and a third of total GHG emissions. In the United States, ten states produce over half of building emissions.

When you're a business looking to calculate your GHG emissions, the carbon footprint of your office(s) and any other buildings your company owns or leases is a logical starting place. Here we'll share some actionable tips and steps to measure your office's carbon footprint. Keep in mind office emissions are just one part of your company’s overall carbon accounting inventory.

What's a Carbon Footprint, and How Do You Calculate it?

A carbon footprint is the amount of GHG emissions released over a certain period of time by an entity, asset, or object, like an office building. Greenhouse Gas Protocol, the international standard for carbon accounting, defines a common unit for measuring carbon footprints, as well as three scopes for categorizing your business’s carbon footprint: Scope 1, 2 & 3.

The common, global, established accounting unit for carbon footprint and emissions measurement is the greenhouse gas carbon dioxide (CO2), and "carbon equivalents" (CO2e) - the sum of carbon plus all other emissions like methane converted into carbon

Scope 1, 2 & 3 define the location(s), boundary, and amount of control an organization has over certain types of emissions.

Scope 1, 2, 3 Emissions Calculation for Office Buildings with GHG Protocol

When you calculate and add these different emissions categories and scopes together, the sum is your company’s total emissions, or carbon footprint in CO2e.

Measuring the Carbon Footprint Emissions of an Office Building

Office carbon emissions may include Scope 1, Scope 2, and Scope 3 emissions:

  • If you own a building and control an energy source (like an owned, on-site power generator), those emissions are categorized as Scope 1 "direct emissions"
  • If your office or building purchases electricty, steam, heat, or cooling from an energy utility or municipal source, those emissions are Scope 2 "indirect emissions"
  • Additionally, most offices also have Scope 3 emissions from sources like employee transportation, employee commuting, and waste generated on-site

To calculate your office's full carbon footprint, you'll need to collect your energy, resource use, and activity data in each of these areas, assign an emissions factor to each one, and add everything up. If you're looking for an automated way to do this, our intelligent sustainability software can save time and simplify emissions tracking, measurement, and reporting.

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However, if you don't have budget for sustainability software, you can also perform this type of carbon calculation the "traditional way" in a spreadsheet. This will be easier if you only have one office (or a small number of total buildings), and you have time to research and gather the right emissions factors for each spend, resource, and activity category.

Regardless of your organizaton's size and resources, or whether you own or rent your office, you can still measure and reduce your office’s CO2 emissions, paving the pathway towards being a more sustainable company.

How to Calculate Carbon Emissions from an Office Building

Office Carbon Footprint Measurement Step 1: Energy & Resource Use

Electricity use is one of the most important and straightforward aspects of an office’s carbon footprint. If your office uses limited refrigeration (i.e., there's one refrigerator in the break room, it's reasonably modern, and isn't leaking), then electricity and lighting are likely to be a leading component within your office's resource footprint.

How do you calculate your carbon footprint from electricity?

  • The most common data source for this will be monthly electricity bills from your utility which list the kilowatt hours (kWh) of electricity used. In some cases, you may also be able to access your electricity meter data directly
  • If you own your office, another option is to install wireless sensors throughout your building to automate energy data collection from various sources
  • However, if you rent or sub-lease a portion of a building, or work in a co-working space, you may not have direct access to your bills or meters. In this case, you'll need to make an assumption about your office's electricity usage based on its area (square feet or meters), location, and the type of building. Or try asking your landlord for assistance
  • Once you have your electricity usage data or estimate, use an appropriate emissions factor to convert your electricity usage into CO2e

Next, you'll want to repeat the same process for your office's other energy and resource consumption areas:

  • Heating
  • Cooling and air conditioning (A/C)
  • Ventilation
  • Water

Together, these components typically represent around 15 kWh of energy usage per square foot of office space, based on our research, data, and U.S. averages.

Office Water Meter to Calculate Carbon Emissions and Footprint

And yes, water does have emissions associated with it. Water use requires energy to supply, treat, and transport it, including electricity used during water purification, or to heat up hot water. For more, see our guide to calculating emissions from water usage.

Office Carbon Footprint Measurement Step 2: Refrigeration and Cooling

Refrigeration is often overlooked in emissions measurement, but can be a significant carbon footprint source depending on your office's cooling needs and usage. Globally, cooling from refrigeration and air conditioning accounts for an estimated 10% of worldwide CO2 emissions.

Common refrigerant chemicals - hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) - are potent greenhouse gases that are thousands of times more potent than carbon dioxide. As a result, it's important to audit and calculate your office's cooling and refrigeration use:

  • How many refrigerators do you have?
  • What's the make and model of each refrigerator? Is it Energy Star certified? Does it receive regular maintenance and inspection?
  • What other sources of cooling does your office rely on? How energy and emissions-intensive are they?
  • Are vehicle air conditioners in scope?

It's important to audit and research these questions, or you might be under-counting refrigeration emissions. On average, refrigeration and equipment account for most of the energy used in a commercial building.

Seasonal temperature changes, office location, construction approach, and level of use can all impact your office’s carbon footprint as well. For example, if you have an office in a state like Arizona, Florida, or Texas, your A/C use will likely be higher, particularly in the summer. Make sure you consider these factors in your calculation for more accurate results.

Office Carbon Footprint Measurement Step 3: Employees

It’s important to remember your office has a Scope 3 emissions footprint as well - one that's closely linked to your employees. Employee commuting, business travel, and waste management can also be material contributions to your office's GHG emissions.

Transportation accounts for 38% of CO2 emissions in the U.S., primarily from air travel and driving gas-powered cars and trucks. At an employee level, it's important to understand how your non-remote employees get to work each day. If your office is in a densely populated city, and most of your employees commute via public transportation, biking, or walking, your footprint will be lower compared to offices with lots of suburban or remote commuters driving to work.

While employee commuting emissions might seem like an individual’s responsibility, those emissions must be included in your company’s Scope 3 emissions calculation. By comparison, if you have employees working remotely, your business does not need to account for an employee's home energy usage while working - however you're welcome to take that into account if you choose to.

To perform this analysis:

  • Find your company’s total number of employees
  • Find or estimate what percent of your employees work remotely
  • Account for any part-time or hybrid employees who are commuting into the office less than five days a week
  • Segment your employees by office location
  • If you’re able to, conduct a commuting survey to determine the number of car, bus, and rail miles or km your employees travel within a given month or year. If you can't survey, use estimates.
  • Apply an appropriate emissions factor to each commuting method, and count up your carbon
Office Employee Commuting Carbon Calculation

If every American who can work remotely does, it'll cut annual, total U.S. GHG emissions by 3-4% (~215 million MT of CO2e)

Follow a similar set of steps for employee business travel. Gather your travel and expense data, segment travel activities by type, estimate the distance traveled, then use it to calculate the emissions impact of employee travel.

Office Carbon Footprint Measurement: Full Checklist

For a comprehensive Scope 3 emissions assessment, go category-by-category. For example, what purchased goods and services does your office use? You'll need to assign emissions factors to office furniture, equipment, food, waste, and other resource consumption aspects of your operations.

If you're not using an automated carbon accounting tool like Brightest, make sure your full carbon calculation checklist accounts for:

  • Electricity
  • Heating
  • Refrigeration and cooling
  • Ventilation
  • Water
  • Waste
  • Vehicles and equipment
  • Employee commuting
  • Employee travel
  • Property maintenance and management like lawn care and landscaping (if applicable)
  • Servers (if applicable)
  • Purchased goods and services

Whichever method you choose to calculate your office's carbon footprint, a sound emissions measurement baseline is one of the best steps for ongoing management and improvement. Once you've calculated your business's carbon footprint, you can start taking smart steps to reduce it, including purchasing renewable energy, improving operational energy efficiency, and developing more environmentally responsible travel and commuting policies.

If we can be helpful to you or your organization’s sustainability journey, please be in touch.