Facing the many possible actions for decarbonizing an event (digital badges, vegetarian menus, electric shuttles, hybrid format), one question keeps coming up: where do you start?
The answer lies in a simple hierarchy, directly inspired by the sufficiency logic promoted by ADEME (the French environment and energy management agency): avoid, then reduce, then substitute, and only as a last resort, contribute. The order isn't arbitrary. It ranks actions from most to least effective, and it protects you from the most common trap in "responsible" events: offsetting what you could have avoided emitting in the first place.
Level 1 — Avoid: the most effective lever, and the simplest
Before any optimization, ask whether each object, action, or trip is actually necessary. This is the most powerful lever, because its effectiveness is 100%: an avoided emission needs neither a low-carbon alternative nor an offset.
A few concrete examples:
Promotional giveaways. The best giveaway is the one you don't produce. A promotional item involves raw material extraction, manufacturing (often in Asia), transport, and end-of-life disposal, for an object that's frequently thrown away or forgotten. Non-material alternatives (show tickets, donations to a charity) eliminate this entire emissions chain.
Exhibition carpet. Laid down for a few days and then thrown away, it has become the symbol of avoidable event waste. Removing it avoids both the manufacturing of a single-use plastic product and its end-of-life treatment.
Air travel. As covered in the article on transportation, a kilometer traveled by short-haul flight emits roughly 80 times more CO₂e per passenger than a kilometer by high-speed train (≈260 g versus ≈3 g, according to ADEME's Base Empreinte®). Avoiding a round trip between Paris and Nice by plane in favor of the train saves nearly 400 kg of CO₂e per person — the equivalent of dozens of meals.
Level 2 — Reduce: less volume, less distance, less consumption
What can't be avoided can often be reduced. Here, the nature of the action doesn't change, only its scale.
Food waste is the most striking example: at events, it can account for up to 30% of the volume prepared (source: ADEME, which estimates food waste in France at 10 million tonnes per year, a significant share of which comes from institutional and event catering). Adjusting quantities to the actual number of registered attendees and arranging for surplus donations reduces this item without affecting the attendee experience.
Other reduction levers: optimizing logistics flows (full loads, grouped trips), choosing a turnkey venue to avoid furniture and technical equipment deliveries, and limiting single-use signage to the strict minimum.
Deliveries. Logistics flows can be reduced by choosing a turnkey venue, and also by pooling trips — for example, using the same vendor for both technical setup and general installation.
Communication materials. Designing reusable signage, digitizing badges and programs, and planning a more minimal, 100%-rented stage design all help reduce single-use items and therefore waste.
Level 3 — Substitute: same need, lower-carbon alternative
For everything remaining after avoidance and reduction, look for the lowest-carbon option that delivers an equivalent service. This is the level where the numbers speak for themselves:
The plate. According to ADEME's Impact CO₂ comparison tool, a meal with beef represents about 7 kg of CO₂e, versus about 0.5 kg for a vegetarian meal. At an event with 1,000 attendees, replacing a red-meat lunch with a vegetarian menu saves roughly 6.5 tonnes of CO₂e, for a single meal service alone.
Energy. A generator powered by HVO (hydrotreated vegetable oil) instead of diesel reduces greenhouse gas emissions by up to 80–90% over the fuel's life cycle, according to data from suppliers compliant with the European RED II directive. Grid connection remains, in France, the lowest-carbon option when available.
Tableware and containers. Reusable dishware, deposit-return containers, water fountains instead of bottles: all substitutions that eliminate single-use waste without compromising the experience.
Level 4 — Contribute: as a last resort, never as an alibi
Once the first three levels have been maximized, there remains a balance of unavoidable emissions. This — and only this — is where carbon contribution comes in: the voluntary funding of carbon sequestration or avoidance projects.
Two essential clarifications. First, on terminology: it's called "contribution," not "offsetting" or "compensation," because no project actually "neutralizes" your emissions — carbon neutrality can only be considered at a planetary scale. Second, on requirements: a credible project must meet five criteria — additionality (it wouldn't have happened without your funding), permanence (the carbon avoided or stored stays that way durably), independent verification (certified by a recognized third party), measurability (avoided or sequestered emissions are regularly measured), and uniqueness (each credit is unique and can only be funded once). Contribution should never serve as an alibi for not acting upstream: funding forest preservation or tree planting doesn't make an event designed without any effort toward sufficiency acceptable.
Why this order changes everything
This hierarchy isn't just a principle — it's a daily decision-making tool. Faced with each choice (Is this custom-built booth necessary? Can deliveries be reduced? Is there a lower-carbon alternative?), it requires working back up the chain in the right direction.
And to make these trade-offs, you need to be able to measure them. That's the whole point of an upfront estimate: comparing scenarios (vegetarian vs. traditional menu, electric vs. combustion-engine shuttles) while there's still time to choose. That's exactly what Climeet makes possible, by instantly calculating the impact of each option.
💡 To go further, download our Playbook for a low-carbon event, a complete guide to measuring, reducing, and managing the impact of your events.
