Ive been in the game for many years. Im quite interested in how people are sizing up the capacity of the units. I seem to go to many houses and find the systems under capacity. I know some people size by the meter square and i know alot of domestic air conditioning guys guess.

http://www.calculator.net/btu-calcul...heat&x=51&y=11

I have come across this site and it seems to be most practical as it accounts ambient temp but not other factors. Then there are some sites which are useless and hard to understand.

I quote for the air conditioning unit to be able cool and heat the whole house with out zoning of half the house or undersizing units. I always calc the size and go the next size up.

There was a way at tafe to size up houses but cant seem to get hold of it. Your comments are appreciated.