Sourcing and provenance

Draft — pending legal review. This policy may change before the first public release.

Rules

• Record where every number came from. Each entry lists its basis: the source type, title, link where there is one, and who made any estimate.
• Never copy a paywalled table.
• Label estimates as estimates. An expert estimate is graded D and names its editor.

Source types

From strongest to weakest:

1. Observed data. Opt-in and anonymized, published only as aggregates above a minimum sample size.
2. Public government documents. For example municipal asset management plans (AMPs) and capital asset policies.
3. Manufacturer manuals. Stated in our own words, with a link to the original.
4. Standards. Referenced by clause number only, never by their text.
5. Open research. Only where its licence is compatible with CC BY 4.0.
6. Expert estimates. From named editors, labelled as such.

How many sources agree, and of what type, sets the confidence grade.

Privacy

An observation never identifies an owner, building or address in public output. Observations are described by region and building type only.

Corrections

If a value is wrong, or a source is misrepresented or should not be used, write to [email protected] with the entry link. Corrections are published as a new version; earlier versions stay at their permanent links.