The thermodynamics of heated and non heated swimming pools is quite complicated. Here at NOA we wanted to make it easy for pool builders and designers to predict the amount of energy needed to heat a pool, or to calculate the temperature of a pool at a given time during the year. The following calculator uses geographic data combined with solar and wind data to accurately calculate these thermal parameters. The program also incorporates pool features such as pool covers, insulation, and wind breaks. For more complicated pool designs feel free to contact us for consultation.

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Select the Months you plan on heating your pool:

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec


This program utilizes published equations of thermodynamics to compute and chart two major characteristics of an operating outdoor pool, which are:

  1. The average monthly water temperature of a non-heated pool
  2. The monthly cost of heating a pool to a specified water temperature

The computed costs are for heating only and do not include the cost of running circulation pumps and other equipment. The primary benefit of this program is the ability to compare the cost benefits of various energy saving features which can be added to a pool.

The following steps will gather weather data for your location, pool dimensions, if the pool is heated, and what energy saving features you want to include in your design.

Please click begin to start

Step 1 – Choose Location

Water temperature and heat transfer are highly dependent on local weather conditions (temperature, wind, humidity, and solar radiance). This program utilizes 30 year average weather data from the National Climate Data Center (NCDC) data base for major cities throughout the United States.


You should select the closest city to your location, or a city that closely represents the typical weather of your location. Average weather parameters for the selected city are displayed in a chart at the bottom of the results. If a detailed site-specific analysis is desired please contact us.

Step 2 – Pool Dimensions

Input the approximate dimensions of your pool. The most critical number here is the surface area of the pool. Water features extending beyond the footprint of the pool which are only operated periodically may be ignored. However, if water features are to be operated on a regular basis their estimated exposed water surface area should be added to the total surface area of the pool. Where a feature utilizes falling water, its estimated surface area should be doubled to account for both exposed sides of the water.
Pool Surface Area (sq.ft)
Pool Perimeter (ft)
Average Depth (ft)

Step 3 – Heated or Non-Heated? Non-Heated Selected

Choose one of the following two conditions to determine either the monthly water temperature or monthly heating costs:
heated pool

  1. Non-Heated Pool – Program will compute the average monthly pool water temperature and number of “swimmable” days for a user specified minimum swim temperature. Enter the desired minimum water temperature.
  2. Heated Pool – Program will compute the average monthly heating cost to maintain a user specified minimum water temperature. Enter the desired water temperature and select the type of heater to be used. You must also enter the local cost of the appropriate form of energy the heater will use; natural gas, propane, or electricity. The most recent utility bill or delivery invoice should have the unit cost of energy.

Select your pool type:

Desired Water Temperature (F)
Heater Type
Cost per Therm ($) ?
Heater Efficiency ?
Cost per Gallon ($)
C.O.P. ?
Cost per kWh ($)
Select Heating Season Months
Swim Season Water Temperature (F) ?

Step 4 – Select Energy Saving Features

For any conditions selected in the previous three (3) Steps you can specify any number of energy saving features and track their individual or combined effect on water temperature and/or heating costs. The program will chart a history of each set of input parameters. It is a good idea to start by selecting no features and then add them one at a time so that you can compare temperature and/or cost savings of each.

Pool Cover

Pool covers offer the greatest energy savings and swim season lengths. It is important to cover your pool when not in use. Select below to add a cover and also select the type of cover you will be using.

Solar Heater

Roof mount solar collector which heats your pool

Solar collector area (sq. ft)
Solar Heater Efficiency

Wind BreakAdded

If the pool is located in an urban setting with surrounding homes, fences and trees, then a wind break is assumed by default. However, if the pool is in a rural setting or surrounded by a large open area, then please click “Remove Wind Break”.


If your pool is shaded you will lose some solar radiation gains.

Percent of the pool that is shaded. (%)

Insulated Shell

A finite analysis program was used to estimate heat loss into the surrounding soil. Initially the amount may not seem significant when compared to losses off the surface; however, when other energy saving features are utilized such as a cover, the percent of potential savings becomes more significant. Generalized values have been used in this program. If a more site specific analysis is desired or for ideas on ways to insulate a shell, please contact our office.

Results History for Non-Heated Pool
Run Number Set Pool Temp (F) Swim Season Length (days) Options


Monthly Water Temperature (F)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec


Results History for Heated Pool
Run Number Set Pool Temp (F) Est. Annual Heating Cost Options


Monthly Heating Costs
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec



Weather Data for Location (Yearly Average)
Season Average Temperature (F) Humidity (%) Wind Speed (MPH) Solar Radiation (W/m^2)