CO₂ reporting is becoming increasingly relevant for companies. The main drivers are new European reporting obligations, rising customer requirements, and audits across supply chains. Companies with electrified vehicle fleets, in particular, face a very practical question: How should electricity be accounted for when electric company cars are charged at employees’ homes?
When charging at home, electricity is supplied via employees’ private meters. From the company’s perspective, however, this electricity still constitutes a business-related energy consumption that must be correctly measured, allocated, and included in CO₂ reporting. This article explains how that works, how charged kilowatt-hours are converted into reliable CO₂ values, and what needs to be considered when dealing with green electricity and the risk of double counting.
What Is CO₂ Reporting and Why Is It Gaining Importance Now?
CO₂ reporting refers to the structured collection, calculation, and disclosure of a company’s greenhouse gas emissions. It is based on internationally established standards such as the Greenhouse Gas Protocol. In the European Union, these requirements are being further specified through the European Sustainability Reporting Standards (ESRS).
With the Corporate Sustainability Reporting Directive (CSRD), the group of companies subject to mandatory reporting is expanding significantly. Many small and medium-sized enterprises are also affected indirectly—for example, because large customers request emissions data or require sustainability information for supply chain assessments.
The goal of CO₂ reporting is to make emissions transparent, enable comparability, and support informed decisions on emission reduction measures.
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Classifying Emissions by Scope 1, 2, and 3
For CO₂ reporting purposes, emissions are divided into three categories:
Scope 1 includes direct emissions generated by the company itself, for example from combustion-engine vehicles or on-site heating systems.
Scope 2 covers indirect emissions from purchased energy, primarily electricity that is sourced from external suppliers rather than generated internally.
Scope 3 includes other indirect emissions along the value chain, such as business travel or employee commuting.
This distinction is crucial for correctly classifying the home charging of electric company cars.
Correctly Allocating Home Charging of Electric Company Cars
When electric company cars are charged at home, electricity is drawn from the employee’s private household supply. Nevertheless, this electricity represents a business-related energy consumption, as it is used exclusively for business travel.
To include this consumption in CO₂ reporting, the charged electricity must be clearly measured and allocated to the company. From 1 January 2026, flat-rate reimbursements will no longer be permitted in Germany. Instead, consumption-based recording of charged kilowatt-hours will be a prerequisite for tax-free reimbursement.
From a CO₂ reporting perspective, electricity used for home charging is generally assigned to Scope 2, as it represents purchased energy attributable to the company. Employee commuting remains clearly separate and continues to fall under Scope 3, Category 7.
Technical Requirements for Reliable Data
Various technical solutions can be used to ensure proper allocation of electricity consumption. These often include separate meters or wallboxes equipped with MID-certified meters. In certain cases, systems compliant with German calibration law (Eichrecht) may also be required.
It is essential that metering data is digitally available and can be documented in an audit-proof manner. Only then can electricity consumption be reliably used for both reimbursement and CO₂ reporting purposes.
With the Charge Repay Service from Phoenix Contact, these consumption data are already available on a per-vehicle basis. They provide a robust foundation for CO₂ accounting. Direct CO₂ reporting based on this data is currently in preparation.
From Kilowatt-Hours to CO₂ Emissions
Emissions are calculated based on the amount of electricity charged. First, kilowatt-hours are recorded per vehicle and reporting period. These values are then multiplied by an appropriate emission factor.
In Germany, the Federal Environment Agency (Umweltbundesamt) provides quality-assured emission factors that can be used for CO₂ accounting. While the calculation itself is straightforward, methodological consistency is critical.
Companies must define whether they report their Scope 2 emissions using a market-based or location-based approach and document this decision clearly and consistently.
Correctly Accounting for Green Electricity
It is often assumed that electricity can automatically be treated as emission‑free if green electricity is shown on the invoice. For CO₂ reporting purposes, this is only permissible if robust and auditable accounting evidence is available.
In Germany, this evidence is provided through Guarantees of Origin, which are cancelled in the official Guarantees of Origin Register operated by the German Environment Agency (Umweltbundesamt). Only if such certificates are available may electricity be reported as renewable in CO₂ accounting.
Home charging in particular offers significant potential to optimize the carbon footprint. Without appropriate evidence, emissions must be calculated using the emission factor of the German electricity mix. If employees can provide proof that they purchase certified green electricity, these energy volumes may be accounted for differently.
When implemented correctly, the use of verified green electricity can reduce the need for compensation measures and thus lead to cost savings.
Why Commuting Must Be Considered Separately
Employee commuting—regardless of the type of vehicle or drive system—must always be assigned to Scope 3, Category 7. These emissions must be recorded separately and must not be mixed with electricity used for business-related charging processes.
Clear separation ensures transparency and avoids errors in reporting.
Outlook: CO₂ Reporting Directly from the Charge Repay Service
The required consumption data are already available. In the future, these data will be directly converted into CO₂ metrics, including the consideration of green electricity logic. The goal is an automated Scope 2 calculation per vehicle that can be used directly for CSRD and ESRS reporting as well as for internal sustainability KPIs.
