Sustainability and resource use
Keeping an event sustainability evidence log
After the event someone will ask what you actually achieved, and the answer needs to be in records, not in memory.
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The short answer
An evidence log lists, for each objective, what was measured, the source record, who collected it, the date and its status: observed, estimated or not measured. Fill it in during the event and in the week after, not months later.
The log is the only source for any statement in your report. If a figure is not in the log, it is not in the report. The benefit evidence tracker is the tool for this, and the log feeds the claim review before anything is published.
What counts as evidence
Evidence is a record that someone else can inspect: an invoice, a delivery note, a supplier's written count, a dated photograph of a storage box, a signed handover form, a registration export.
A verbal remark is a lead, not evidence. Write it down, with who said it and when, and mark it as stated by that person.
The three statuses
| Status | Meaning | Example | May be reported as |
|---|---|---|---|
| Observed | Counted or recorded by your team or shown by a document | 25 programmes printed, shown on the printer's invoice | A fact, with the source |
| Estimated | Calculated from other records with a method you can state | Lunch portions served worked out from the caterer's closing count | An estimate, with the method |
| Not measured | No record was collected | Venue energy use; venue declined to share | Not measured, with the reason |
Rules for a log that holds up
- One row per measure, one named collector, one date.
- Keep the source file or link, not just the figure.
- Record supplier statements as stated, and note where nothing was verified.
- Do not infer an outcome from attendance or satisfaction scores. Record only what was measured.
- Keep personal data out of the log unless the privacy owner has agreed what may be kept and for how long.
Sequence
- Copy each objective into the log before the event, with its measure and owner.
- Tell collectors what to record and where to save the source.
- Collect during the event and on the next working day.
- Review the log with the owners and fill gaps while records are fresh.
- Freeze the log, then write the report from it.
Worked example · Fictional example
A log for three objectives
Fictional organisation and figures, for illustration only.
A fictional institute logs three objectives. For printed materials it records 30 printed against 250 the previous year, from invoices. For food it records ordered and served counts from the caterer. For signage it records seven signs kept, shown by a dated photograph.
Venue energy use is marked not measured because the venue did not provide it. When the report says the institute reduced printing, it cites the two invoices. It makes no statement about energy.
Use this yourself
Sustainability evidence log
Copy one row per measure. Attach the source before you set the status.
| Objective | Measure | Figure | Source record (file or link) | Collected by | Date | Status: observed / estimated / not measured | Notes |
|---|---|---|---|---|---|---|---|
| Print on request only | |||||||
| Record leftover food | |||||||
| Reuse signage | |||||||
| Venue resource data |
Handle it in-house, or bring in help?
Your team can usually handle this when
- Two to four objectives, a few collectors and a team that saves invoices and supplier statements.
- You write a short internal report.
Outside planning help earns its fee when
- Many suppliers and several events feed one report.
- The report will be published, shared with funders or a board, and needs checking first.
- You need to tie the log to supplier requirements and handover documents.
Want the evidence log built into your plan?
An Event Blueprint can set the objectives, the collector for each, the source records and the timing, and tie them to supplier requirements and handover. It keeps observed, estimated and not measured apart. Send your objectives and the suppliers who will hold the records.
Questions organisers ask
How long should we keep the evidence?
Decide with your finance and privacy owners. Keep source files for as long as the report may be referred to, and keep personal data out of the log.
Can a photograph count as evidence?
It can show that an item existed at a time, if it is dated and stored. It does not show how much was saved or what the impact was.
What if we forgot to collect something?
Mark it not measured, note why and add the collection step to next year's plan.
Related resources
Content record: Draft. Written from the cited sources and checked by automated rules; not yet independently reviewed.