10.5% of live EPC certificates could not be retrieved at all — 14 of 133 sampled across twelve postcodes on 2026-09-05.
One reported instance (tenure: 'ND') turned out to be three variants of the same mistake: assuming a single upstream shape where the government sends several.
| Field | Value | Certs | Schemas |
|---|---|---|---|
tenure |
'ND' |
3 | SAP 16.1, 19.1.0 |
built_form |
'NR' |
5 | RdSAP 21.0.1 |
co2_emissions_* |
{"value": 1.8, "quantity": "tonnes per year"} |
6 | SAP 13.0 |
ND ("unknown") and NR ("Not Recorded") are first-class keys in the upstream code tables, not absences — so they are carried and labelled rather than normalised away.
No contract change. Verified live: 133/133 certificates fetch, 0 failures.
Code-only release — the PPD snapshot artifact is untouched.
Full detail in CHANGELOG.md.