Air temperature and humidity of indoor-side and outdoor-side test rooms are controlled in accordance with the JIS conditions. Then, the equipment under test is installed and operated. The test room is equipped with air temperature and humidity measuring instruments and an airflow measuring apparatus capable of measurement with high accuracy. By determining enthalpy from the measurements of temperature and humidity of air entering and leaving the equipment under test, cooling or heating capacity of the equipment under test can be measured with high accuracy. In addition, by providing the outdoor-side test room with the facilities enabling intake of fresh air and discharge of engine’s exhaust gas, test of gas engine-driven heat- pumps is also possible.