Is grey fleet included in Scope 1 or Scope 3?

Grey fleet is Scope 3 Category 6 (Business Travel) because the vehicles are owned by employees, not the company. The company does not have operational control over these vehicles. Only company-owned or leased vehicles under operational control are Scope 1.

How do I calculate grey fleet emissions without knowing vehicle types?

Apply DEFRA’s average car emission factor to total claimed business miles. This gives a reasonable estimate. For better accuracy, collect vehicle registration numbers from employees and use DVLA data to identify vehicle types and apply specific emission factors.

Grey Fleet

Grey fleet refers to employees’ personal vehicles used for business travel, with emissions typically reported under Scope 3 Category 6.

What is Grey Fleet?

Grey fleet is the often-overlooked component of business travel emissions. When employees use their own cars for work journeys and claim mileage expenses, the associated emissions are the company’s responsibility under Scope 3 Category 6 (Business Travel). Grey fleet can be significant for organisations with dispersed operations, mobile workforces, or inadequate pool car provision.

Calculating grey fleet emissions requires mileage data (from expense claims) and assumptions about vehicle type and fuel efficiency. DEFRA publishes average car emission factors that can be applied when specific vehicle data is unavailable. More accurate calculations use employees’ actual vehicle makes and models.

Grey fleet management has safety, cost, and environmental dimensions. From a carbon perspective, organisations can reduce grey fleet emissions by providing pool cars or EV pool cars, offering salary sacrifice EV schemes, promoting public transport alternatives, and implementing virtual-first meeting policies.

Practical Examples

A social care provider discovers that 500 staff members claim a combined 3 million business miles per year in their personal cars, representing 900 tCO₂e of grey fleet emissions.

A company introduces an EV salary sacrifice scheme and within two years, 30% of grey fleet miles are driven in employee-owned EVs, reducing grey fleet emissions by 25%.

An NHS trust replaces grey fleet journeys with pool EVs at key sites, reducing both mileage costs and Scope 3 emissions while improving duty of care.

How Climatise Helps

Climatise calculates grey fleet emissions from mileage expense data, applying DEFRA factors by vehicle type. The platform tracks the shift from ICE to EV grey fleet vehicles and quantifies the resulting emission reductions.

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