Nuno,

I have used the IndoorPoolCalc.xls spreadsheet tool for analyzing indoor
pool heating and dehumidification energy.

It is available here:
http://www.energyideas.org/documents/spreadsheets/IndoorPoolCalc.xls

It can be used to find energy savings resulting from using a pool cover,
changing air/water temperature and humidity setpoints, new boiler, new
dehumidifier and so on. It is based on the Shah Method--see "Calculating
Evaporation from Indoor Water Pools", HPAC Engineering, March 2004.

I hope this helps,

Eric Wilson