Method

No instrument has been run in any room for this site. Every quantity here belongs to a published study or to a manufacturer's own technical documentation, and the sentence using it says which.

Where do the figures come from?

Peer-reviewed sleep and building-science work first, manufacturer technical sheets second, each linked at the point it is used.

Primary work is preferred to a summary of it. Where only a secondary account exists, the page admits that rather than dressing the citation up as something firmer.

What original work does this site do?

Counting. Where a figure belongs to this site it is a tally of documents read on a given date, and the tally states how many.

A count is not a measurement and is never offered as one. Anybody can repeat a count by opening the same documents. Nobody can repeat a reading that was never taken.

What would change a page?

A superseded study, a document rewritten since it was read, or a reader who demonstrates the tally was wrong.

The fix goes into the sentence that carried the error. The review date at the foot moves when it does.