Why don “inverter” type air conditioners get a higher star rating?
For standard air conditioners (which use single speed compressors) the efficiency does not vary significantly at part load – reduced load output (heating or cooling) is achieved by cutting in and out of the thermostat or temperature control system. Inverter units use a variable speed drive in the motor system that drives the compressor. While these systems tend to look less efficient at full load (ie their star rating at rated capacity, which is the rating on the energy label, is not always as high as conventional air conditioners), they tend to be very efficient at part load operation, which is a more common mode in a typical household. This is achieved by reducing the continuous compressor output which increases the efficiency of the refrigeration system (as the apparent size of the condenser and evaporator is larger). Performance does vary between models, so the actual part load performance of inverter units should be sought from manufacturers.
