night time running and temperature setting of 26 deg C..
i am pretty sure the AC can reach the set temperature and the compressor will reduce speed to save power.
the fan speed of the AC will not consume much electricity.
the main thing is the compressor, but even at 80% running, it'll be around 640W x 10 hours?
6.4kWh.. x 0.5 cents x 30 = RM 96..
try sleeping with your kids 1 night and see read the meter again in the morning!