Event emissions inventory: how to measure and offset

Why measure an event's emissions

Corporate events, congresses, trade fairs, conventions, award ceremonies, festivals: they are intense concentrations of economic activity in a short window of time. Thousands of people travel, use energy, generate waste, and consume food and materials. The result is a significant carbon footprint that, without measurement, goes unnoticed.

Pressure for sustainable events is growing on three fronts. First, participants and sponsors expect environmental responsibility, particularly at events tied to ESG, innovation and sustainability. Second, regulation is starting to require transparency: ISO 20121 (sustainable event management) and PAS 2060 (carbon neutrality) set out frameworks for carbon-neutral events. Third, measurement is a precondition for improvement, because without knowing where the emissions sit you cannot cut them in the next edition.

Measuring an event's footprint also produces a powerful communications asset. A carbon-offset seal with full traceability demonstrates genuine commitment, unlike vague sustainability claims with nothing behind them.

Emission sources at events (travel, energy, catering, waste, materials)

An event's emissions fall into five main categories.

Participant travel. Usually the largest source, at 70-80% of the total footprint. It covers flights, ground transport (car, coach, taxi, ride-hailing) and accommodation. The average distance travelled and the transport mode determine the volume. International events with participants from other continents have disproportionately larger footprints than regional ones.

Venue energy. Electricity for lighting, climate control, sound, video, exhibition equipment and technical infrastructure. The footprint depends on the length of the event, the size of the space, the venue's energy efficiency and the emission factor of the local grid. Venues with their own solar generation or renewable energy contracts cut this share.

Food and drink. Catering generates emissions in food production (agriculture, livestock, processing), transport and refrigeration. Meals heavy in beef have a significantly larger footprint than vegetarian or vegan options. Food waste makes it worse.

Waste. Disposables, packaging, food waste, and build-up and break-down materials. Final destination (landfill, recycling, composting) determines the emission factor. Events with waste management, source separation, composting of organics and reverse logistics cut this share substantially.

Materials and build. Temporary structures, set design, print, giveaways, signage. New materials carry a larger footprint than reused ones. Build and break-down logistics (equipment transport, diesel generators for installation) also contribute.

GHG Protocol methodology for events

An event emissions inventory follows the same logic as the corporate GHG Protocol, adapted to the temporary, concentrated nature of an event.

Setting boundaries. Which emissions to include? The recommendation is to draw them wide: participant and staff travel, venue energy, catering, waste, materials and logistics. Leaving out relevant categories undermines the credibility of the inventory.

Data collection. Each source needs specific data. For travel, you need the origin of participants, the mode used and, ideally, the cabin class for flights. Pre-event surveys (via the registration form) and data from partner airlines are the main sources. For energy, the venue supplies consumption data. For catering, the caterer reports volumes and menu. For waste, post-event weighing documents what was generated.

Calculation. Each piece of activity data is multiplied by its emission factor. MCTI factors for Brazilian fuels and electricity. Defra for international flights. IPCC for waste. The total in tCO2e is the event's footprint.

Report. The report documents boundaries, data sources, emission factors, assumptions and results by category. It has to be clear enough to be verified by a third party and understandable to non-technical stakeholders.

Offsetting with certified, verified credits

Once the footprint is measured, the company can offset residual emissions by buying and retiring certified carbon credits. Offsetting does not replace reduction: the hierarchy is always measure, reduce, then offset the residual.

For events, offsetting usually covers 100% of the measured footprint, which supports a claim of "carbon-offset event" or "carbon-neutral event" (subject to the applicable standard, such as PAS 2060 or ISO 14068).

Credit selection follows the same integrity criteria discussed in the article on REDD+ credits: additionality, permanence, independent verification and co-benefits. Mangue Tech, in partnership with Carbonext, offers Amazon forest conservation credits certified under Verra VCS.

The carbon-offset certificate

Once the credits are retired in the Verra registry, Mangue Tech issues a carbon-offset certificate carrying: the event's name and date, the total measured footprint (tCO2e), the number of credits retired, the carbon project identification (name, location, standard), the serial numbers of the credits, and the signature of the technical lead.

That certificate is a valuable communications asset. It can be published on the event site, on social media, in press materials and in the sustainability reports of sponsors. Full traceability, from inventory to credit to project, protects against accusations of greenwashing.

How to engage us

Engaging Mangue Tech for an event inventory is straightforward.

1. Briefing. You tell us the type of event, estimated number of participants, location, duration and the scope you want. Mangue Tech prepares a proposal with a schedule specific to your event.

2. Data collection. The Mangue Tech team sets up the collection forms (integrated into the registration platform where possible) and coordinates with the venue, the caterer and suppliers.

3. Calculation and report. After the event, the data is processed on the Mangue Tech platform and the report is produced for internal review before final delivery.

4. Offsetting and certificate. The credits are bought and retired in the Verra registry, and the certificate is issued once the report is approved.

For recurring events, Mangue Tech offers annual contracts with differentiated terms and benchmarking across editions, so you can measure reduction progress over time.