It is well known that inverter-driven variable speed compressor (or inverter) air-conditioners are more efficient than constant speed compressor air-conditioners. Therefore, most of the countries have adopted part-load assessment test standards such as ISO 16358, EN 14825 and ASHRAE 116 in addition to the conventional ISO 5151 of full load test standard to evaluate appropriately the part-load efficiency of variable speed air-conditioners. However, many countries in the Middle East and South America still stick to ISO 5151 standard for policy or high temperature environmental reasons. In this study, we experimentally verify the energy saving effect of the inverter air-conditioner compared to the constant speed air-conditioner in the Korean climate with distinct temperature changes of four seasons and in the hot climate of Saudi Arabia during the year. ISO 5151 defines test conditions in a purposed single temperature condition, whereas ISO 163 58, EN 14825 and ASHRAE 116 simulate seasonal efficiency using several dimates test results' interpolation. Regardless of all theses test standards, this sturly directly applies the environmental changes during a dqy or season in a qualified test room with specific size. Through the extensive regional and seasonal dimate data in Saudi Arabia and South Korea, changes in temperature conditions are applied direc-tly to the outdoor side and appropriate heat flux conditions to the indoor side of the air-enthalpy type test room. Constant speed and variable speed (inverter) air-conditioner performances are compared in these test room conditions when the same target temperature of indoor side is maintained by the air-conditioner operation. The energy savings of the inverter air conditioner are analyzed experimentally acwrding to the spatial and temporal temperature changes of the two muntries. Results show that energy reduction effects of using inverter air-conditioner are largely depend on the temperature and tooling load changes for a day or a season.