Carbon Emissions Estimator

Formula

TotalCO2e = Scope1(Fuel) + Scope2(Electricity) + Scope3(SupplyChain)

We use the GHG Protocol framework. Emissions are calculated by multiplying activity data (e.g., kWh of electricity, miles flown) by standard Emission Factors (e.g., kg CO2e per unit) to derive a normalized Carbon Dioxide Equivalent (CO2e) in Metric Tonnes.

Worked Examples

Example 1: Small Office

Problem:1000 kWh, 0 Gas, 0 Travel.

Solution:S1=0. S2=0.38t. S3=0. Total = 0.38 Tonnes.

Result:Low Impact

Example 2: Traveling Sales Team

Problem:0 kWh (WeWork), 50k Miles Flight.

Solution:S3 = 7.5 Tonnes.

Result:High Scope 3

Frequently Asked Questions

What is Scope 1?

Direct emissions from sources you own or control. Examples: Gas boilers in your building, fuel burned in company vehicles.

What is Scope 2?

Indirect emissions from the generation of purchased energy. Examples: Electricity, steam, heat, or cooling consumed by your office.

What is Scope 3?

All other indirect emissions in your value chain. Examples: Business travel, employee commuting, waste disposal, and purchased goods/services. Usually the largest category (80%+).

What is CO2e?

Carbon Dioxide Equivalent. A metric that bundles all greenhouse gases (Methane, Nitrous Oxide) into a single number based on their Global Warming Potential (GWP) relative to CO2.

Why measure Scope 3?

It's often the biggest part of your footprint. Regulators (SEC, EU CSRD) are increasingly requiring Scope 3 disclosure.

How accurate is Spend-based data?

Spend-based (EEIO) is a rough proxy ('We spent $10k on steel'). Activity-based ('We bought 5 tons of steel') is far more accurate but harder to track.

What is the GHG Protocol?

The global standard framework for measuring and managing greenhouse gas (GHG) emissions.

How many trees to offset 1 tonne?

Roughly 50 trees growing for one year capture 1 tonne of CO2. Or, preserving 0.1 hectares of forest.

Does WFH count?

Yes, Employee Commuting and Teleworking are Scope 3 categories. WFH reduces commuting emissions but increases home energy use.

How do I calculate my carbon footprint?

Carbon footprint is measured in metric tons of CO2 equivalent (CO2e) per year. Add emissions from energy use (electricity and heating), transportation (miles driven times emission factor), diet, and consumption. Average US individual footprint is about 16 metric tons CO2e per year. Use EPA emission factors for accuracy.

Background & Theory

The Three Scopes Explained

Scope 1 (Burn): Anything you burn. Fleet vehicles, furnaces.
Scope 2 (Buy): The electricity you plug into.
Scope 3 (Beyond): Everything else. Supply chain, travel, waste.

Calculation Methods

Activity-Based: Best. Uses physical units (liters, kWh).
Spend-Based: Okay. Uses financial data ($ spend). Good for screening.

Practical Tips

Start with Energy: Scope 1 & 2 are easiest to get from utility bills.
Engage Suppliers: Ask your biggest vendors for their footprint. Actual data beats estimates.

History

The Kyoto Protocol

In 1997, the Kyoto Protocol operationalized the UNFCCC, committing countries to limit GHG emissions. This created the need for standardized measurement.

The GHG Protocol

In 2001, WRI and WBCSD launched the GHG Protocol Corporate Standard. It invented the concept of "Scopes" (1, 2, and 3) to prevent double counting while ensuring comprehensive reporting. It remains the gold standard today.

The Rise of ESG

In the 2010s, investors began demanding Environmental, Social, and Governance (ESG) data. BlackRock and others pushed for climate transparency. Carbon accounting moved from the "CSR Department" to the "CFO's Office." Software like Watershed and Persefoni emerged to automate the math.

Common Misconceptions

Myth: "We don't manufacture anything, so we have no footprint." Reality: Services companies have massive Scope 3 footprints from cloud servers, travel, and procurement.
Myth: Offsets are a get-out-of-jail-free card. Reality: The Science Based Targets initiative (SBTi) requires *reduction* first. Offsets are only for the last 10%.