What if some of my emissions data is missing?
On This Page (5 sections)
Estimate the missing data with a reasonable method, record how you did it, and replace the estimate with real data when you can. Do not leave a large source out because data is missing. Small gaps, filled sensibly and explained, are normal in carbon accounting.
Common gaps and how to fill them
| Gap | Common estimate |
|---|---|
| A missing month of electricity | The average of the months before and after, or the same month last year |
| A site with no meter | Floor area × the kWh per square metre of a similar site |
| Unknown fuel for a vehicle | Distance × an average fuel use for that vehicle type |
| No refrigerant records | Equipment charge × a typical annual leak rate for that type of equipment |
| No supplier data | Spend × an average spend-based factor |
| Incomplete commuting survey | Survey results scaled up to the total number of staff |
How to estimate well
- Find the gap. Note which site, source and months are missing, and why.
- Judge its size. Estimate how much it could change the total. A large gap needs a careful estimate and a plan to fix it.
- Choose the most specific data that you have. Your own data from another period or site is usually better than an industry average.
- Be conservative when unsure. Where an estimate is uncertain, avoid choices that make emissions look lower than they probably are.
- Record the method. Write down the data, the assumption and the result, so that a reviewer can repeat it.
What to disclose
The GHG Protocol asks you to disclose and justify any exclusions. For estimates, explain the main methods and assumptions in your report. IFRS S2 also asks how much of your Scope 3 uses specific or verified data, so estimates must be visible, not hidden.
Leaving a source out is a last resort. It is acceptable only if the source is small and estimating it would cost far more than its value to readers. Say what you left out and why.
Close the gaps over time
- Ask why each gap happened, for example a missing meter or a contractor who did not report.
- Fix the cause before the next period.
- Track the share of your total that is estimated, and aim to lower it each year.
Step 6: Calculate your emissions explains how to choose factors for your estimates.
Sources
- GHG Protocol Corporate Standard, chapters 1, 7 and 9
- GHG Protocol Technical Guidance for Calculating Scope 3 Emissions
- IFRS S2 Climate-related Disclosures, paragraphs B38–B57
