An event's Bilan Carbone®: which categories weigh most and how to reduce them in 2026

An event's Bilan Carbone® measures its greenhouse gas emissions in tonnes of CO₂ equivalent. It covers three scopes: direct emissions (scope 1, generators and technical fleet), venue energy (scope 2, electricity and air conditioning), and indirect emissions (scope 3, participant transport and accommodation, catering, production and waste). Scope 3 represents 85 to 95% of the total. This is where everything is decided.

The decision weighing 60 to 80% of the footprint is made at the design stage, well before logistics. It concerns format (in person, hybrid, remote) and location (accessible by train or dependent on flights), rather than giveaways, catering or waste sorting. An event that understands this starts with an advantage.

1Why measure an event's footprint in 2026?

Regulation. The AGEC law bans disposable tableware and the free distribution of printed materials at public events. Public procurement has included an environmental clause and criterion in every contract since 22 August 2026. BEGES is mandatory above 500 employees, while, since the Omnibus I Directive, CSRD covers only groups with more than 1,000 employees and €450 million in turnover.

Sponsors and corporate clients. Seminars, conventions and trade shows feed participating companies' scope 3. Buyers assess event providers on their ability to supply a per-participant footprint. An event without a documented assessment loses competitiveness in the corporate segment.

Reputational risk. DGCCRF penalises claims such as "carbon-neutral event", and the European EmpCo Directive has prohibited those based on offsetting since 27 September 2026. Participants ask the question before registering. A credible approach is an asset; having no approach is a risk.

Financial management. Carbon and cost categories overlap: transport, catering, energy and physical production. Making catering plant-based, removing giveaways and going hybrid reduce the footprint and budget simultaneously.

2Transport, catering, production: where emissions lie

The typical emissions breakdown follows a stable pattern from one in-person event to another. Participant transport represents 65 to 85% of the total, by far the dominant category, with air transport accounting for 70-90% of it whenever flights are involved. Catering accounts for 5 to 15%, strongly correlated with the share of meat, especially beef, in menus. Accommodation represents 3 to 10% for multi-day events. Venue energy (lighting, air conditioning, sound) represents 2 to 8%. Physical production (signage, stands, giveaways, printing) accounts for 3 to 10%, peaking at shows with stands. Digital technology and streaming remain marginal for an in-person event (less than 3%) but can reach 5-10% for a poorly designed hybrid event.

Orders of magnitude vary enormously by type. A regional seminar for 200 people accounts for 15 to 40 tCO₂e. A national conference with 500 to 800 participants accounts for 80 to 200 tCO₂e. A trade show with several thousand visitors can reach 400 to 1,500 tCO₂e. An international conference with predominantly air travel passes 500 tCO₂e and can exceed 2,500 t. A public festival ranges from 2,000 to 15,000 t depending on the share of local attendees. The footprint per participant varies by a factor of 10 between a local seminar and an international conference, almost entirely because of transport.

3From collection to action plan: the method in 2-3 months

An initial event Bilan Carbone® takes 2 to 3 months and 20 to 40 hours of internal work. The five steps: defining boundaries (one day, scope, reference edition, scoping note), collecting data (2 to 4 weeks, the bottleneck, where 80% of the assessment's quality is decided), applying emission factors from ADEME's Base Empreinte (1 to 2 weeks), analysis and sector benchmarking (3 to 5 days), a quantified reduction plan with the steering committee (2 to 3 weeks). Collection is the crux: without preparing it beforehand through registration forms and supplier briefs, the rest is improvised.

4Five mistakes that undermine initial event assessments

Incomplete boundaries. Publishing a footprint without participant transport because it is "not directly controlled" removes 65 to 85% of actual emissions. The figure becomes incomparable with any sector reference. An assessment without transport scope is an internal logistics assessment rather than an event assessment.

Measuring everything in the first year. The classic result: stalled collection, discouraged teams, questionable figures and abandonment after a year. The right strategy: one well-run pilot event in the first year, gradual expansion over 2 to 3 years and certification in year 3 once the approach is mature.

Confusing intensity with absolute value. The footprint per participant may fall while the total rises if attendance grows. Both indicators must be monitored together. Assessment without an action plan. An isolated assessment without a quantified trajectory and named people responsible loses all operational value. "Carbon-neutral" communication. Since 2023, DGCCRF has penalised this type of claim and the European Commission has regulated it. Committing to a reduction trajectory (-30% between edition N and N+3) is infinitely more credible than a badge of self-proclaimed neutrality.

5Format, location, catering: measures that change the order of magnitude

Hybrid format (-40 to -60%). A well-designed hybrid, in person for nearby participants and remote for those who would have flown, halves the footprint without compromising the experience. The additional technical cost (dual-stream production, dedicated facilitation) is more than offset by transport and catering savings.

Location choice (-30 to -40%). The venue's geography accounts for a third of the footprint before the first participant registers. A national event in a city served by high-speed rail inevitably emits less than in a city dependent on flights. Internationally, Paris, Amsterdam, Brussels and Frankfurt allow a shift to rail that an isolated destination never will. Modal shift (-10 to -20%): SNCF group fares (Congrès TGV INOUI Pro programme), train tickets included in registration and promoting trains in advance communications.

Plant-based catering (-2 to -3 t for 500 participants). A beef meal: 5 to 7 kg CO₂e. A vegetarian meal: 0.8 to 1.5 kg. Across 500 people and 4 meals, the switch saves 2 to 3 tonnes with zero or negative additional cost. Vegetarian catering quality has improved enormously, making the choice increasingly less divisive.

Reduced physical production. Reusable badges, modular signage reused between editions, 100% digital programmes via QR codes and removing non-essential giveaways (€3 to €8 each, rarely useful). Reduced digital use. Streaming capped at 1080p, no dedicated app if a website is sufficient, and hosting with a provider using a low-carbon electricity mix.

6Our advice: where to start

Three actions to launch this week, with no budget, laying the foundations for a lasting approach.

1. Add two fields to the registration form. Departure city and planned transport mode. This can be configured in five minutes in any tool (Google Forms, Eventbrite, Weezevent). Without these data, calculating transport, 65 to 85% of the footprint, is a rough estimate. With them, it becomes mechanical.

2. Brief your caterer on a predominantly vegetarian option. A beef meal emits 5 to 7 kg CO₂e, a vegetarian meal 0.8 to 1.5 kg. Across 500 people and 4 meals, that is 2 to 3 tonnes saved with zero or negative additional cost. Offer a vegetarian menu by default with meat on request: reversing the default changes everything.

3. Negotiate an SNCF group fare. The Congrès TGV INOUI Pro programme offers participants discounts of 15 to 25%. Include the link in registration confirmations. Automatic effect: 10 to 20% modal shift from flights and cars to trains. Cost for the organiser: zero. Combined impact of these three actions: 10 to 25% reduction from the next edition. Hybrid format and venue choice will follow naturally in the subsequent edition once the first assessment's data have spoken.

7Frequently asked questions

8Key takeaways

• 65 to 85% of an event's emissions come from participant transport: this category determines the footprint.
• Three structural choices dominate the result: format (in person/hybrid), venue (accessible by train) and the audience's geographical composition.
• Collection happens in two places: the registration form (city, transport mode) and invoices (energy, catering, accommodation).
• Three actions with no budget change the order of magnitude: transport fields on the form, predominantly vegetarian catering and SNCF group fares.
• Bpifrance's Diag Décarbon'Action funds the organising company's Bilan Carbone® if it has fewer than 500 employees (€6,000 excluding VAT payable): funding covers the company's GHG inventory as a whole.

A well-executed event Bilan Carbone® does not need to be complex: it needs to be maintained over time. Measure one edition to establish a starting point, set two or three concrete actions for the next, then repeat. This rhythm turns a one-off exercise into an approach credible to clients, local authorities and participants. The three actions to launch this week, transport fields on the form, a catering brief and a group train fare, cost nothing and lay the foundations.

Further resources

Frequently asked questions

1How much does an event Bilan Carbone® cost?

Between €4,000 and €12,000 excluding VAT for an initial assessment alone of a medium-sized event (500 to 2,000 participants). Between €10,000 and €30,000 including an action plan and team support. If the organiser is a company with fewer than 500 employees, Bpifrance's Diag Décarbon'Action can fund 40% of a €10,000 excluding VAT fixed fee for the company's own Bilan Carbone®, rather than an isolated event, leaving €6,000 excluding VAT payable.

2How long does an event Bilan Carbone® take?

2 to 3 months for the first edition measured, including 20 to 40 hours of internal work over that period. Timing depends on suppliers' responsiveness (caterer, venue, technical services) and the quality of data gathered through registration. Anticipated from design, collection is almost mechanical; reconstructed afterwards, it becomes a nightmare.

3What are an event's main emission categories?

Participant transport (65 to 85%), catering (5 to 15%), accommodation (3 to 10% over several days), venue energy (2 to 8%) and physical production (3 to 10%). Transport alone concentrates most of the footprint, and this is where the largest reduction measures lie, through format and location choices and incentives for modal shift.

4Should an event's footprint be published with or without participant transport?

With, every time. An assessment without participant transport removes 65 to 85% of actual emissions and makes the figure incomparable with any sector reference. Good practice is to publish the complete assessment, clearly distinguishing directly controlled emissions (venue, catering, production) from transport-related emissions (indirectly controlled through location choice and incentives). This transparency is expected by public specifications and corporate sponsors.

5Is a 100% remote event really low carbon?

Yes, substantially. A remote participant emits 1 to 5 kg CO₂e for a day compared with 150 to 300 kg for short-haul flying, or 50 to 100 times less. But it is not zero: video streaming, devices and hosting have a real footprint. To reduce it, cap resolution at 1080p, turn cameras off when they add nothing, and host with a provider using a low-carbon electricity mix.

6Can you claim a "carbon-neutral" event?

Technically possible, commercially risky, legally exposed. Since 2023, DGCCRF has penalised unsubstantiated claims, and the European EmpCo Directive has prohibited any neutrality claim based on offsetting since 27 September 2026. Since 2022, ADEME has recommended avoiding this wording. Defensible practice is to publish the total footprint, reduction actions implemented and any offsetting of residual emissions with complete traceability (project, methodology, third-party verification). A documented reduction trajectory is infinitely more credible than a neutrality badge.

7What are typical orders of magnitude for emissions per event?

A regional seminar for 200 people accounts for about 15 to 40 tCO2e, and a national conference with 500 to 800 participants for 80 to 200 tCO2e. A trade show with several thousand visitors can reach 400 to 1,500 tCO2e. An international conference dominated by flights exceeds 500 tCO2e, sometimes 2,500 tCO2e, and a public festival lies between 2,000 and 15,000 tCO2e depending on the share of local attendees. The footprint per participant varies by a factor of 10 between a local seminar and an international conference, almost entirely because of transport.

8Which measures reduce an event's footprint?

Measures changing the order of magnitude are decided at the design stage. A well-designed hybrid format, in person for nearby participants and remote for those who would have flown, cuts the footprint by 40 to 60%. Choosing a venue served by high-speed rail accounts for 30 to 40%, and rail incentives (group fares, a ticket included in registration) deliver 10 to 20% modal shift. Next come vegetarian catering by default, saving 2 to 3 tCO2e for 500 people and 4 meals, then reduced materials: reusable badges and signage, and removing giveaways.

9What method and standards framework apply to an event's carbon footprint?

The calculation follows the Bilan Carbone® method across the 3 scopes, using ADEME's Base Empreinte emission factors; scope 3 (participant transport and accommodation, catering, production, waste) represents 85 to 95% of the total. An initial measurement takes 2 to 3 months in 5 steps: scoping, collection, applying factors, analysis and reduction plan. Beyond calculation, ISO 20121 governs sustainable event management and can be certified by a third party, a step to target once the approach is mature, often in the 3rd year.

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