CO₂ savings are the estimated reductions in greenhouse gas emissions achieved by switching from a higher-emission option to a lower-emission one—most commonly comparing electric vehicles (EVs) to internal combustion engine (ICE) vehicles, or comparing renewable-powered electricity to fossil-heavy electricity. In EV charging, CO₂ savings are usually calculated based on the kWh delivered, the carbon intensity (gCO₂e/kWh) of the electricity, and the emissions from the displaced petrol/diesel driving.
What Are CO₂ Savings?
CO₂ savings represent the difference between two emission scenarios:
– Baseline scenario (what would have happened without the change)
– New scenario (what happens with the cleaner option)
In practice, CO₂ savings are often expressed as:
– kgCO₂e saved per charging session
– kgCO₂e saved per vehicle, fleet, or site per month/year
– gCO₂e saved per km (when translating charging into driving distance)
Why CO₂ Savings Matter
CO₂ savings are used to demonstrate the climate impact of EV adoption and charging infrastructure. They support:
– Customer and fleet sustainability reporting
– ESG metrics and climate disclosures
– Public funding and grant eligibility reporting
– Corporate climate targets tracking
– Marketing and stakeholder communication (when calculated transparently)
For charging operators, CO₂ savings metrics can also strengthen site-host partnerships and differentiate their charging offers.
How CO₂ Savings Are Calculated for EV Charging
A simplified CO₂ savings calculation compares ICE driving emissions to EV charging emissions:
Step 1: Estimate EV Charging Emissions
– EV emissions (kgCO₂e) = kWh delivered × (gCO₂e/kWh ÷ 1000)
This requires a defined electricity emissions factor (average or time-based).
Step 2: Estimate Displaced ICE Emissions
ICE emissions are typically estimated from:
– Vehicle fuel consumption (L/100 km)
– Tailpipe CO₂ per liter of fuel (petrol/diesel)
– Distance driven equivalent to the charged energy
Distance is estimated using EV efficiency (kWh/100 km) or, if available, actual vehicle telemetry.
Step 3: Calculate CO₂ Savings
– CO₂ savings = ICE emissions – EV emissions
A positive result indicates emissions reduction; the size depends heavily on electricity carbon intensity and the baseline vehicle assumptions.
Key Factors That Strongly Influence CO₂ Savings
CO₂ savings can vary widely based on assumptions and data quality. The biggest drivers are:
Electricity Carbon Intensity (CO₂ per kWh)
Lower grid emissions or renewable sourcing increases CO₂ savings.
– Using carbon-aware charging or cleaner time windows can improve savings.
– A clear definition is needed if using clean energy matching or certificates.
Baseline ICE Vehicle Assumptions
Savings depend on what is being replaced:
– A diesel SUV baseline yields higher “savings” than a small efficient petrol car baseline
– Real-world driving and fuel economy can differ from standard values
EV Efficiency and Charging Losses
– Vehicle efficiency (kWh/100 km) changes the km-equivalent of a charging session
– Charging losses (charger + vehicle) slightly reduce savings if included
Better reporting clarifies whether losses are included in the calculation boundary.
Geography and Use Case
– Regional grid mix differences can change EV emissions significantly
– High-mileage fleet electrification often generates larger absolute savings than occasional private charging
CO₂ Savings Reporting Best Practices
To keep CO₂ savings credible and defensible:
– State emissions factor source and timeframe (annual average vs hourly)
– Define boundaries (location-based vs market-based electricity emissions)
– Use transparent baseline assumptions for the ICE comparison
– Provide both total savings and intensity metrics (per kWh, per km)
– Separate measured data (kWh delivered) from estimated data (km driven)
– Avoid overclaiming by implying exact savings when inputs are estimates
Common Pitfalls
– Using generic ICE baselines that exaggerate savings
– Claiming “zero-emission charging” without defining the electricity sourcing method
– Mixing national annual averages with real-time claims
– Ignoring uncertainty ranges and presenting savings as exact numbers
– Double-counting renewable attributes across multiple reporting claims
Related Glossary Terms
CO₂ Savings Reporting
CO₂ per kWh
Carbon Intensity
Carbon-Aware Charging
Clean Energy Matching
Carbon Footprint Reporting
Climate Targets
kWh Delivered per Charger