Start with runtime, not marketing claims
Cooling cost falls when the compressor draws less power, runs for fewer hours, or operates at a lower average load. Thermostat set point, direct solar gain, air leakage, filter condition, room size, humidity, and equipment condition all influence that runtime.
Test one operational change at a time
Compare a modestly higher set point, targeted fan use, closed doors, shaded windows, and clean filters under similar weather. Avoid comparing an unusually cool day with a heat wave. A smart meter, plug meter, or equipment app can provide stronger evidence than a bill alone.
Know when equipment efficiency matters
Replacement can make sense when an older or poorly sized system runs heavily, but simple efficiency labels do not guarantee short payback. Compare installed cost, expected annual energy, maintenance, climate, and remaining equipment life across low, typical, and high-use scenarios.
Run your own scenario