Credits and licences

Last updated 2026-10-11

Our own code

The tools and page layouts are written for this site. The pages make no requests to other servers.

The calculators use published equations and constants, typed into our own code:

Refrigerant saturation pressures (PT charts, superheat and subcooling): tables generated once with CoolProp (MIT licence) from the published equations of state it implements; the pure fluids match the NIST Chemistry WebBook within 0.01 %. Blends (R-454B, R-448A) come from CoolProp’s mixture model and can differ from a manufacturer’s chart by 1–2 psi.
Psychrometrics (dew point, wet bulb, enthalpy, humidity ratio): the ASHRAE Handbook—Fundamentals psychrometric equations (Hyland–Wexler saturation pressure), with the Magnus (Alduchov & Eskridge) and Stull formulas as cross-checks.
Room air conditioner sizing: the ENERGY STAR room air conditioner sizing chart and adjustments (U.S. EPA / DOE).
Duct friction: Darcy–Weisbach with the Colebrook friction factor; rectangular-to-round equivalence by the Huebscher equation.
Heat loss: conduction U × A × ΔT plus infiltration from air changes per hour; radiator output correction with the exponent 1.3 used for panel radiators (EN 442 test method).
Units: international table BTU (1,055.05585262 J); 1 ton of refrigeration = 12,000 BTU/h.

No third-party code, fonts or data files are loaded by the pages (data/credits.json, rendered below).