At start up, during the 20 minutes it takes to cool the room, the compressor will be operating at full capacity and the fan will also be in operation. The compressor will switch on and run when the temperature rises and switch off when the room has been cooled again every 10 minutes. Accordingly, in the first hour, the compressor and fan will be in operation for 40 minutes, and only fan will be in operation for 20 minutes. For the remaining 9 hours, in every hour, the compressor and fan will run for 30 minutes, and only the fan will run for 30 minutes. How much power consumption does that work out to?
| Activity | Formula | Power Consumption (KWH) |
| First Hour | ||
| Compressor run for 40 minutes (2/3rd of an hour) | 2/3 x 1500/1000 | 1.00 |
| Fan (80W) operates for 60 minutes (1 hour) | 1 x 80/1000 | 0.08 |
| Remaining 9 Hours | ||
| Compressor runs for 30 minutes (1/2 an hour) every hour | ½ x 1500 x 9/1000 | 6.75 |
| Fan (80W) runs throughout | 80 x 9/1000 | 0.72 |
| Total | 8.55 | |