An inverter AC will ordinarily cool the room to the desired temperature faster than a fixed speed AC, but that may not make a significant difference in power consumption. Once the room has been cooled to the pre-set level, the compressor will operate continuously, but the variable speed drive will supply just enough power for the compressor to maintain the temperature at the set level. The compressor will consume only 1/4th of its rated power output. Thus, a 1.5KW (1500W) compressor will operate at 375W consumption to maintain the desired temperature.
| Activity | Formula | Power Consumption (KWH) |
| First Hour | ||
| Compressor run for 20 minutes (1/3rd of an hour) | 1/3 x 1500/1000 | 0.50 |
| Compressor run for balance 40 minutes (2/3rd of an hour) | 2/3 x 375/1000 | 0.25 |
| Fan (80W) operates for 60 minutes (1 hour) | 1 x 80/1000 | 0.08 |
| Remaining 9 Hours | ||
| Compressor runs for 60 minutes (1 hour) every hour | 9 x 375/1000 | 3.375 |
| Fan (80W) runs throughout | 80 x 9/1000 | 0.72 |
| Total | 4.925 | |