Project design document (PDD)
The founding description of a carbon project: boundary, baseline, methodology, monitoring approach and expected results.
The project design document states what the project is, where its boundary lies, which methodology it follows, how the baseline was determined, and how results will be measured and verified. It is the reference against which later performance is judged.
Because it is written before results exist, the PDD is where assumptions are most exposed. Baseline construction, additionality argument, leakage assessment and permanence arrangements all appear here in full, and each becomes a commitment the project must later honour.
Revisions are permitted but must be justified and, depending on the standard, re-validated. Drift between the design and actual practice is one of the clearest signals that a project is not delivering what it claimed.
Frequently asked questions
Is the PDD public?
Under most major standards it is published in a registry, sometimes with commercially sensitive annexes withheld.
Can a project change methodology later?
Usually only with justification and re-validation, since changing the rules mid-crediting alters what the results mean.