How to Build a Geothermal Cooling System

basement with bikes, skis, and a window
  • 2-8 hours
  • Intermediate
  • 20-300
What You'll Need
Two fans
Moisture meter
Dehumidifier (optional)

A geothermal cooling system uses the temperature of the earth to cool homes. The temperature below the surface of the ground fluctuates less and is better regulated by not being exposed to the wind and the sun. A home can use the ground's temperature to cool its own by constructing such a system.

Geothermal cooling systems can be complex or very simple. Some use pumps, heat exchangers, and air ducts. Others simply use a couple of fans to create a cool air passage. This is an inexpensive alternative to cooling your home.

Step 1 - Use the Home's Basement

As the source of the system will be the earth, you will need access to it within the home. This means the home will need to have a portion residing below ground (i.e., a basement).

Step 2 - Reduce Humidity

Reduce the relative humidity in your basement by using a dehumidifier. This may not be necessary if your basement is dry. Run the dehumidifier until the relative humidity has dropped below 60 percent. Use a moisture meter to check the humidity level.

Step 3 - Prepare Air Flow

basement window with grass and flowers outside

To create a way for the air to flow up from the basement to the areas you want cooled, we need to create an airstream. If you have a basement window, it makes this process easier. Open a basement window, if available. Close all the windows on the upper floors. Close the doors to any rooms you don't need to cool. This will divert the cool air to the areas where it's needed most. Now find the highest window in the upper floor. Open this window. Since hot air rises, this is where the heat will escape from the house.

Step 4 - Run the Fans

Now it's time to run fans. You can use portable fans or install permanent ones. The fans will create the stream of air entering and exiting your home, thereby channeling cool air from the basement upward. Turn on a fan in the basement, with the air flow pointed toward the upstairs. Now go to the highest window on the upper floor you opened. Place a fan in the window with the air flow projecting outside the house. This will suck the air blowing up from the basement and discharge the warm air out of the house.

Step 5 - Watch the Time

At some point during the day, the basement may begin to warm up. This is because heat from the sun is warming the earth. If you have a deep basement, you will experience this less. Watch the temperature of your basement. If it begins reaching a temperature near the upper floor, you may have realized your cooling potential. Running your fans after this point may only push warm air into the upper floors instead of cool air.

With this simple system, you should be able to reduce the temperature of your home by several degrees. It will also save you money by not running the air conditioner.