We live in Kowloon. The air-con at the living room will be turned on at 6 p.m. and switched off at 10:30 p.m everyday. Then, we turn on the air-cons of two bedrooms until 6-7 in the morning (the air-con of my daughter's room will be turned off when my daughter wakes up, which maybe 8 or 9 a.m.) Our bill was only $6xx.