About

Editorial Policy

The rules we follow so that a number on this site can be trusted, and what we do when one turns out to be wrong.

Last updated

What we publish

We publish calculators and the guides that explain the inputs those calculators depend on. We do not publish news, product reviews or rankings, because those invite the kind of opinion that cannot be checked. Every page must answer a question a reader actually has, in a way the reader can verify.

How calculators are built

  1. The formula comes first. Before any text is written, the calculation is specified as a formula with named inputs, and the formula is printed on the page under “How we calculate this”.
  2. The defaults are sourced. Each default input is traced to a public source, listed in the assumption table with the date it was checked. We prefer official statistics, standards and manufacturers’ own specifications; where a figure is a judgement, the table says so.
  3. The code is tested. Every calculator has a set of test cases with answers worked out by hand, including unit conversions. A calculator is published only when all of them pass, and the tests are kept and rerun whenever the calculator changes.
  4. The examples are the code’s. The worked examples on each page are computed by the same code as the live calculator, so they cannot drift apart.

How guides are written

Guides explain mechanisms, not opinions. Every factual claim must come from a source we can name, and we prefer to show the arithmetic rather than assert a conclusion. Guides end with the calculators they support.

Use of AI tools

We use AI writing tools to draft text, to check arithmetic, to suggest test cases and to find inconsistencies between a calculator and its page. We do not publish anything those tools produce without a person reading it, checking its figures against the sources, and taking responsibility for it. The formulas, the defaults, the sources and the final wording are editorial decisions made by people. We say this because readers should know how the text they rely on was made.

Sources

We cite sources where a figure is used and list the main ones on the methodology page. We link to the source document where it is freely available. When a source is updated, we update the figure and the “last reviewed” date; when a source is withdrawn, we find a replacement or remove the figure.

Advertising and independence

Advertising on the site is served by Google AdSense, is labelled, and is placed by our page templates, not by the advertisers. Advertisers have no influence over what we publish and are not told what we are working on. We do not accept payment for coverage, sponsored content, or links, and we do not carry affiliate links; if that changes, the affected pages will say so clearly.

Corrections

If you find an error, write to contact@hvacscalculator.com or use the contact form. Error reports are checked before anything else. When a calculator is found to be wrong, we fix it, add a test case for the error, and note the change in the page’s update date. When a guide is wrong, we correct the text and, for errors that could have misled a reader, add a correction note at the point of the change.

Updates

Every calculator and guide shows the date it was last updated, and every assumption table shows the date its figures were last reviewed. We review all defaults at least once a year and whenever a source publishes new data.