The build quality and type of thermal insulation varies so greatly in the Algarve that sometimes this is difficult to easily quantify.
A very simple and more accurate way of finding out how much your air conditioning is costing is to turn off all your major appliances in the villa and take an initial meter reading. Come back after an hour and take another meter reading and minus this from the initial reading which will indicate your energy consumption in KW per Hour as a base rate. Turn on all your aircon units on maximum and come back after an hour and take a final reading. Use this formula to estimate your maximum aircon consumption:
final reading - (base rate)*2 - initial reading = KW per hour energy consumption of your air conditioning units at maximum.
Check your EDP bill and there will be a Euro Rate per KW hour and use this to calculate how much it is costing per hour.
You might be surprised at the cost.
The reason for this is that most of the cheaper air conditioning units have a very low efficiency rating, (can be rating E and below), which often end up costing you more in the long run. Generally it is better to opt for the "INVERTER" type air conditioners which are more expensive to buy, but can be very efficient (rating A) (cheaper) to run.