Employee commute and working from home emissions calculation

Best-Approach Hierarchy (per GHG Protocol)

The Protocol lists three general methods for calculating Category 7: Employee commuting emissions, ranked by accuracy:

1. Employee Survey Method (Activity-based)

   • Gather commuting patterns (distance, mode, frequency) directly from employees via surveys or HR data.

   • Multiply passenger-km or vehicle-km by appropriate emission factors.

   • Most accurate when response rate is high and the sample is representative.

2. Employer Data Method

   • Use known office locations, employee home postcodes, work schedules, and reasonable assumptions about travel modes/distances.

   • Often combined with public transport maps or GIS tools.

3. Spend-Based Method

   • Use money spent on commuter benefits, parking subsidies, or public transport passes, multiplied by spend-based emission factors.

   • Least accurate and generally a fallback when no activity data is available.

If Few Employees Respond to a Survey

The GHG Protocol anticipates low response rates and recommends:

• Assess Representativeness

  • Compare survey demographics (location, role, department) to the total workforce.

  • If respondents are skewed (e.g., only office staff), results may be biased.

• Upscale the Data

  • If responses are representative, extrapolate average distance/mode/frequency to the full employee population.

• Hybrid Approach

  • If the sample is not representative, combine survey data with:

    • HR address data to model commuting distances for non-respondents.

    • Mode split estimates from regional travel surveys or census data.

    • Industry averages or peer benchmarks.

• Document Limitations

  • Clearly state assumptions, the response rate, and how you adjusted or weighted the data.

  • Flag the estimate for improvement in future inventories.

Trace’s Recommended Approach for Employee Commute Emissions

At Trace, we recommend the survey method as the preferred approach for calculating employee commute emissions. This method not only delivers the most accurate, activity-based data but also serves as an opportunity to actively engage employees in your organisation’s net zero journey.

By asking employees to share their commuting patterns, you open the door for conversations about sustainable travel choices and reinforce the shared commitment to reducing emissions.

Participation Targets

• We recommend aiming for more than 40% total participation in the commute survey to ensure results are robust and representative.

• To support this, Trace provides a participation toolkit within the app — including templates, reminders, and best-practice guidance — to help you encourage employees to take part.

If Participation Falls Below Target

If survey participation is below 40%, we recommend contacting the Trace support team. We can help you:

1. Assess Representativeness – Determine whether the responses reflect the broader workforce’s commuting habits.

2. Decide on Next Steps –

   • If the sample is representative, we can extrapolate results confidently.

   • If not, we may recommend alternative methods such as using HR location data combined with regional travel statistics.

Trace's Transparency in Reporting

Regardless of the method used, Trace ensures that:

• All assumptions (e.g., mode splits, distances, frequency) are clearly stated.

• All calculation steps are documented for audit readiness and stakeholder transparency.

This approach ensures your reported employee commute emissions are credible, traceable, and aligned with GHG Protocol best practice.