Cord wood vs crib wood test fuel
Crib wood is a standardized lab fuel — dimensional lumber nailed into open cribs — used in the traditional EPA test; cord wood testing burns real split logs, closer to how people actually use stoves. The 2020 NSPS allows either: 2.0 g/hr crib-tested or 2.5 g/hr cord-wood-tested.
Crib tests are highly repeatable but flatter than real life; cord-wood tests better predict in-home performance, which is why the EPA and several states have pushed toward them. The database records which fuel each certification used.
When comparing two stoves' g/hr figures, check the test fuel: a 2.4 g/hr cord-wood result and a 1.9 g/hr crib result are not directly comparable numbers.