Scope 3 Category 7: how carpooling can reduce employee commuting emissions

Your organisation can change its electricity supplier, improve building efficiency and review business travel. Employee commuting is different: the journeys happen every working day, but the choices belong to your people.

For sustainability and HR teams, that makes commuting both a challenge and an opportunity. Helping people who normally drive separately share a journey can reduce driving, share costs and ease parking pressure. The important next step is understanding what changed.

This guide explains where commuting fits in Scope 3, how carpooling can help, and how Herdy connects employees with more people going their way.

What is Scope 3 Category 7?

Scope 3 Category 7 covers employee travel between home and work in vehicles the reporting organisation does not own or operate. It includes different transport modes, not just cars. Its significance varies by workplace; it is not automatically every organisation’s largest emissions source. See the GHG Protocol’s employee commuting guidance.

How can carpooling reduce commuting emissions?

Imagine two employees who each drive 20 kilometres to the same workplace. Together, their separate one-way journeys involve 40 vehicle-kilometres. If they share one car and the pickup adds two kilometres, the shared journey covers 22 vehicle-kilometres.

That is 18 fewer vehicle-kilometres for those journeys. Repeated over a working week, small changes can add up. But the reduction comes from replacing separate driving, not simply from recording a passenger booking.

If the passenger would otherwise have walked, cycled or taken an existing train service, the comparison is different. Long pickup detours, different vehicles and journeys made specifically to collect passengers can also change the result. Carpooling should complement other suitable transport options.

A worked example: two commuters, one shared car

The following is a fictional example, not an Australian fleet average or a forecast of Herdy results. Assume both employees would otherwise drive alone, both cars have the same operational emissions factor, and the shared car’s factor remains unchanged with an extra passenger.

If the same arrangement works in both directions, three days a week for 46 weeks, the illustrative annual difference is 894 kg CO₂-e: 3.24 × 2 × 3 × 46 = 894.24 kg. This is a result for the two-person arrangement, not a saving to claim twice or a percentage reduction for the whole organisation.

The 0.180 factor is deliberately illustrative. This example excludes upstream fuel emissions, vehicle manufacture and infrastructure. Actual estimates need suitable factors and a consistent boundary, including relevant changes in fuel use.

What should an employer measure?

The GHG Protocol allows fuel-based, distance-based and average-data calculation methods. Its guidance recommends collecting commuting patterns, including distance, transport mode, commuting days and carpool occupancy. Employee surveys or representative samples can help cover people outside a carpooling programme. Read the calculation guidance.

For a workplace carpooling programme, we recommend starting with three practical questions:

• Are people using it? Track completed shared journeys and repeat participation, rather than registrations alone.
• What driving did it replace? Ask what participants would otherwise have done, and account for pickup detours.
• Can the result be explained? Record assumptions, missing information and the calculation method alongside the numbers.

Choose factors that match the activity, vehicle or fuel, geography and reporting period. Keep the units consistent: a factor per vehicle-kilometre is different from one per passenger-kilometre. Australia’s National Greenhouse Accounts Factors are an official resource for emissions estimation, updated annually; selecting a factor still requires a method appropriate to your data.

A commuting inventory and estimated savings answer different questions

An inventory estimates emissions associated with employee commuting during a reporting period. A separate comparison estimates what might have happened without an intervention.

Reduced driving can lower the commuting emissions reflected in an inventory. However, an estimated avoided-emissions figure should not simply be subtracted from that inventory. The GHG Protocol requires avoided emissions to be reported separately, with the comparison and its assumptions explained. Read the GHG Protocol explanation.

For example, do not calculate an employee’s actual shared commute and then deduct the same estimated saving again. Compare reporting periods using consistent methods, and consider changes in workforce size, attendance and travel patterns when explaining progress.

How Herdy helps organisations put carpooling into practice

A workplace community connected to a wider network

Employees verify their work email to join their organisation’s Herdy group. They can find colleagues, but their options extend to the wider Herdy community.

That matters because a suitable match may work in the building next door. An employee living near someone who travels to the same precinct could share a journey even when nobody in their own team follows that route. More potential matches create more opportunities to find a commute that fits.

Employee choice and shared costs

Employees can offer or find rides, chat and agree arrangements through Herdy. Participation is voluntary. Passengers contribute towards agreed running costs, and Herdy takes no commission from that contribution.

For employers, the practical starting point is making the option visible: introduce the workplace group, explain how people join and help employees try a journey that suits them.

Reporting shaped with founding partners

Herdy is working with founding partners to develop useful employer commuting insights. The example dashboard shows participation, shared journeys and illustrative emissions comparisons. It is a prototype with fictional data, not a verified report.

Founding partners help shape measures, exports and methodology documentation. For rides shared across organisations or with other community members, reporting needs an agreed allocation approach so employers account for their employees’ travel appropriately.

Start with one workplace and learn what works

A useful first rollout does not need to solve every employee’s commute. Choose a site or team where people are interested, and give the programme enough support to find out what helps them participate.

• Understand the starting point. Find out which journeys are being driven separately and where people encounter transport difficulties.
• Make participation simple. Explain work email verification, wider-community matching and voluntary participation.
• Bring HR and sustainability together. Agree the employee communications and the questions reporting should answer.
• Review and improve. Look at repeat journeys, employee feedback and the driving replaced before expanding.

Carpooling gives employers a practical way to support change beyond the workplace. Herdy’s role is to help people make those connections—and work with organisations to understand the result.