Go to the Cooling Calculator

The Air Conditioning Cost Calculator compares the energy use and cost of different types of residential cooling systems.

1.  Click on the region of the continental US that is closest to your home.  This will select a cooling hours figure for the calculator to use.  You can also enter the cooling hours manually if you have better information (see note A, below.)  Click on the "Accept" button to proceed.  You will be taken to the system input page

2.  Using the drop down menus, select a cooling unit for each system.
  • To compare two air conditioners, select the air conditioner type for each system.  The calculator will assign values for the EER/SEER (see note B, below) and distribution efficiency fields.  Make changes to these values if you have better information (see note C, below.)

  • To compare an air conditioner with an evaporative cooler, select the air conditioner in System 1, then click on the "Compare Evaporative Cooler" button.  Input the size of the cooler, expressed either in HP (motor horsepower) or watts.  If you want to switch back to comparing two air conditioners, click on the "Compare Standard AC" button.
3.  Input the size of the air conditioning units to be compared, and select whether this number is in BTUs or tons (BTU - British Thermal Unit, a measurement of energy; one BTU is approximately the amount of heat released by burning a wooden kitchen match.)  One ton is equivalent to 12,000 BTUs per hour.  Room air conditioners commonly use BTUs; larger systems commonly use tons.

4.  Input your electricity cost.  Your local utility (or current utility bill) is the best source for this information.

5.  When you have made your selections, and made any appropriate changes to the default values, hit the "See Results" button.  From there, the calculator will display a results page, which compares the operating costs between the two systems, and tells you how much you will (or won't) save by using one system over another.  From the results page, you can make changes to the two systems, and re-submit the information for new results.

Notes

A.  Note that the cooling hours data selected from the map are only regional estimates that do not take into account the other factors that affect the cost of operating a cooling appliance.  Size of home, thermostat set point, and individual comfort are only some of the factors that go into the operational characteristics of (and therefore cost of) cooling a home.  However, if you wish, you can adjust the cooling hours up or down to reflect your current situation.
EXAMPLE: you're using the calculator to compare your home's current system (system 1) to a new system (system 2.)  After you submit your information, you find that the operating costs for system 1 doesn't reflect the cost of cooling your home.  First, make sure that the system size, efficiency, and distribution efficiency values are correct (to the best of your knowledge.)  If your cooling costs are still not reflected by the results, you can you increase or decrease the cooling hours number until the system 1 operating costs match your actual (or expected) costs.
B.  EER - Energy Efficiency Ratio. Used to compare the efficiency of room air conditioners.  A measure of the number of BTUs per hour of cooling provided for each watt of electricity used.
SEER - Seasonal Energy Efficiency Ratio.  Used to compare the efficiency of central air conditioning systems.  Measures ratio of the total amount of cooling provided in a typical cooling climate for an entire year to the energy consumed in the same period.

C.  For air conditioners, the calculator will assign values to the EER/SEER and distribution efficiency fields.  Please note that these are default values only, based on an average.  Actual values may vary significantly.  For best results, obtain EER/SEER values from the manufacturer.  The values for your distribution system efficiency are best obtained through performance testing or calculation.

D.  Note that the calculator does not take into account the efficiency of the fuel transmission from the source to your home, only the efficiency of the system within your home.

E.  The calculator is compatible with the Netscape Navigator, Microsoft Internet Explorer, and Opera browsers.  The calculator is optimized for use with versions 4.0 and above for all browsers.  Those with earlier versions of the browsers can still use the calculator, but it may not perform to its full capabilities.  To update to the current version of Netscape Navigator, click here.  To update to the current version of Microsoft Internet Explorer, click here.

F.  The calculator is intended for display at a resolution of 800x600 or higher.  If your display settings are lower than 800x600, the calculator may look jumbled or unreadable.  If you are using Windows 95 or greater click Start|Settings|Control Panel|Display to configure your display settings.  Click the Settings tab and then use the Desktop Area slider control to change your display size to 800x600.

Go to the Cooling Calculator