What is the evaporation rate of an outdoor pool in Florida?

Answer

Evaporation rates vary depending on many factors such as relative humidity, air temp, water temp, and wind speed. Also running water features such as spitters, water falls, sheer decents greatly increase the surface area of water increasing the amount of evaporation. The swimming pool construction company I work for considers 1/8 in. water loss per day normal evaporation. Pools that run multiple water features for extended periods of time may lose upwards of 1/4 in. per day.

The evaporation rates of occupied and unoccupied swimming pools have been measured to derive empirical equations for calculating loss. Three references are:

1. Smith, Charles C., George O.C. Lof, Randy W. Jones, "Rates of Evaporation from Swimming Pools in Active Use", ASHRAE Transactions, Volume 104, 1998

2. Smith, Charles C., George O.C. Lof, Randy W. Jones, "Measurement and Analysis of Evaporation from an Inactive Outdoor Swimming Pool", Solar Energy, Vol. 53, No. 1, pp. 3-7, 1994

3. Shah, Mohammed, "Calculating Evaporation Rates from Indoor Water Pools", HPAC Engineering, March 2004

A spreadsheet tool for estimating the heat loss due to evaporation from an indoor pool is available at http://www.energyideas.org/documents/spreadsheets/IndoorPoolCalc.xls.

This tool is based on the reference above by Shah.