# A meter failed for a month. What does the UK CBAM expect?

Canonical: https://senseible.earth/answers/uk-cbam-missing-meter-data

Fill the gap with a conservative estimate and record how you did it. HMRC's UK CBAM guidance suggests, for example, the average flow rate for the same period plus a supplement such as one standard deviation. The method must be written in your monitoring plan before the gap happens.

## Conservative means

The substitute must not understate emissions or overstate production. When in doubt, the estimate leans towards more emissions.

## HMRC's examples

- Missing lab analysis of a fuel: use a standard value.
- An unweighed delivery truck: use the average of similar loads in the same period plus a supplement, for example one standard deviation.
- A failed flow meter: use the average flow rate for the period plus a supplement, or estimate conservatively if no other instrument exists.
- Missing heat measurement: estimate from the process efficiency over the period, plus a supplement.
- A meter reading with higher uncertainty can still be used while it is repaired, as it gives a conservative value.

## What to do now

1. Write your gap-filling methods into the monitoring plan.
2. Keep purchase invoices: they are an independent check on what the meter should have read.
3. Repair or replace the instrument as soon as possible, and review the methods regularly.

## Worked example: gas flow meter down for 30 days

- Daily gas use over the other 335 days: average 4,200 SCM, standard deviation 350 SCM.
- Substitute per day: 4,200 + 350 = 4,550 SCM.
- Gap total: 4,550 x 30 = 136,500 SCM, against 126,000 SCM at the plain average.
- The extra 10,500 SCM keeps the estimate conservative.

## What Senseible does here

Senseible reads monthly fuel and power invoices, which give an independent total to compare against a failed meter. We build the figure from your records and check every figure in-house; for the UK it must then be verified by a verifier accredited for UK CBAM. Have your own verifier? Send it to them.

- [How to fill data gaps](https://senseible.earth/answers/how-to-fill-gaps-in-scope-3-data)
- [CBAM Suite](https://senseible.earth/cbam-suite)

Sources: [HMRC, UK CBAM monitoring, reporting and verification technical guidance (October 2026)](https://assets.publishing.service.gov.uk/media/6ad219fe0f7b53973e02680f/CBAM_technical_guidance.pdf)

Last reviewed 2026-11-02.