# What kiln temperature records does a biochar verifier ask for?

Canonical: https://senseible.earth/answers/kiln-temperature-log-what-verifier-wants

Under Verra VM0044 v1.2, production temperature is logged continuously by an instrument with a recordable signal, such as a thermocouple, and averaged for the year. The sensor is calibrated against a primary device from an independent accredited lab. Without a measured temperature, a default factor of 0.56 applies and credits drop.

## Why temperature changes the credit

For biochar in soil, VM0044 v1.2 sets how much carbon counts as lasting 100 years by production temperature: 0.89 above 600 °C, 0.80 from 450 to 600 °C and 0.65 from 350 to 450 °C. Where temperature is not measured, recorded and reported, the factor is 0.56.

## What the log must show

- A continuous record, rolled up to an annual average.
- A digital or analogue instrument that records its signal, such as a thermocouple or thermoresistor.
- Calibration against a primary device from an independent accredited lab, as often as the maker specifies.
- Written operation and maintenance logs.
- An offsite electronic backup of all logged data, with access for the verifier.

## High technology status needs it too

A facility counts as high technology only if pyrolysis gases are recovered or burnt, at least 70% of the pyrolysis heat is used, pollution controls meet emission limits, and production temperature is measured and reported. Only high technology biochar can go into concrete, asphalt and other non-soil uses.

## Is there a minimum temperature?

VM0044 v1.2 sets no minimum temperature as an eligibility condition. Its permanence table starts at 350 °C, with lower factors for cooler bands. A project can choose a stricter floor, such as 450 °C, to keep every batch in the medium band.

## Example: the same biochar, logged and not logged

- Carbon stored in the biochar before the permanence factor: 100 tonnes CO2
- Kiln logged between 450 and 600 °C: 100 x 0.80 = 80 tonnes counted
- Kiln not measured: 100 x 0.56 = 56 tonnes counted
- Project emissions from fuel and transport are deducted after this

Factors from VM0044 v1.2, Table 3 and footnote 21. The 100 tonnes is an example figure.

## What Senseible does here

On a Senseible project, kiln sensor temperature logs keep each batch's heat record with its lab result, and the automatic flags with kiln at least 450 C, H:Corg at most 0.7, spreading inside the plot and transport distance catch a cold batch on the spot. Senseible prepares and checks the record; an accredited verifier checks it again.

- [Carbon removal projects](https://senseible.earth/carbon-removal/projects)
- [What a biochar lab test checks](https://senseible.earth/answers/biochar-lab-test-what-labs-check)
- [CO2 in a tonne of biochar](https://senseible.earth/answers/how-much-co2-does-a-tonne-of-biochar-remove)

Sources: [Verra, VM0044 v1.2 methodology document: applicability conditions 9 to 14, Section 7 (additionality), Tables 3 and 4, Section 9 (monitoring)](https://verra.org/documents/vm0044-biochar-utilization-in-soil-and-non-soil-applications-clean/)

Last reviewed 2026-11-02.