Full Description Standard 221 prescribes a field evaluation and test method to measure andscore the performance, in terms of delivered cooling or heating capacity or cooling efficiency, of an installed unitary HVAC system.This standard* Defines performance scoring methods for cooling and heating system delivered capacity and cooling system efficiency* Establishes uniform methods of measurements and testing procedures for airflow, temperature, enthalpy, and power* Specifies test instruments, specifications, and calibration requirements for performing such measurements and tests* Specifies data required and calculations to be used* Applies to single-zone unitary split and packaged direct expansion (DX) cooling, air-source heat pump, and combustion furnace HVAC systems of any capacity and with forced-air distribution systems