How to know the piping are suitable for inverter air-cond? what is the piping size fo normal & inverter?

I prefer for inverter type panasonic & daikin, cause i compare to my electricity bill with my friend using a inverter type save alot. My, 1 unit (1hp bedroom) cost me RM120+-/month. my friend 2 unit (1hp bedroom & 2hp living area) cost him also RM120+-/month. Both of us also 2 person stay, bedroom air-cond from night until morning.

For living area better getting 2hp or 2.5hp, cause if the air-cond sense a tempeture not achive a setting, the compresor will run fully on it. At the end your electricity bill will kaukau. Try to calculate the area to decide a size of air-cond. and the heat will spoile your air-cond if long houes fully run.