Calculation sources
Each tool identifies the formula, units, assumptions and relevant sources for its task. Sources include engineering references, government building-science material, university publications and manufacturer data. Use the edition and operating conditions named on the calculation page.
Independent checks
Worked examples show the supplied inputs, substitution and expected result. They help you follow a method but do not validate the data for your installation. Other calculators can provide useful comparisons; their agreement alone does not establish a standard or a complete design.
Access and evidence limits
Some references require access to a standard, a product table or a specific test configuration. Where the required evidence is unavailable, the page explains what is needed rather than supplying an unsupported coefficient or curve.
Applying a result
Check the original source, compatible pressure or airflow boundary and current project requirements before making a decision. See how to read a result and the calculation disclosure for the next checks.