TRAVIS COUNTY, Texas (KXAN) – After nearly an entire summer without rain, storm clouds finally rolled through Texas this week. The rain brought with it cold temperatures that had been absent for months. While many looked to the sky for relief, residents in Whisper Valley looked underground.
“It’s literally underfoot … the ground you’re standing on,” Greg Wolfson said. He was referring to how homes were cooled this summer: geothermal technology.
“Whether you have snow on the ground or it’s 105 degrees outside, it’s always 72 degrees or 74 degrees underground.” Wolfson is the chief technology officer with EcoSmart Solution. The company offers green building options to developers, including solar panels and geothermal technology.
Each home in Whisper Valley, located in far eastern Travis County, is built with energy efficiency in mind, outfitted with solar panels, Tesla Powerwalls and EV chargers.
What’s missing? Air conditioning units. Instead, each house is cooled using geothermal. “They put out less energy than the equivalent sized traditional air source heat pump or certainly the air conditioner,” Wolfson said.
How does heat from the Earth keep a house cool?
Wolfson said geothermal works just like an AC unit, except homes use the earth instead of a big heavy machine.
A pipe runs from each home’s HVAC system into the ground, descending about 30 feet. This deep in the Earth, the temperature stays a constant 72-74 degrees in Central Texas. This temperature changes over thousands of years, but does not fluctuate otherwise.
That pipe is full of water, which flows continuously. According to Wolfson, water absorbs heat much more easily than air. Heat from the HVAC system is pushed into the water, then flows underground where it releases heat into the ground.
“In the winter, the heat pump spins and will basically pull the heat out of the ground and put it into the house,” Wolfson said.
The water then circulates back into the house to absorb more heat. It’s basically a loop.
Deployment of geothermal technology
The system can be accessed via a hatch in the backyard of each home. “All this connection is done before any house is built.” Bundles of cables emerge from the ground where new homes will be built in the development.
According to Wolfson, all the geothermal in the neighborhood is connected to the grid. All pipes are connected to a power center that regulates the system. Cooling towers are also attached to help during days of extreme weather.
Wolfson said because of the connections, if something happens to one home’s geothermal system, it can rely on other homes in the network.
The mesh also means less drilling is required. Wolfson said that for most homes, three holes and three pipe loops would be required to keep those homes cool. Because of the grid, each house requires only one hole and one loop.
If the system is damaged, which Wolfson said is unlikely, the easiest way to repair the geothermal technology is to drill a new hole.
400 homes in Whisper Valley are currently occupied, with another 400 under construction. This is the first of several stages of development. They hope to build apartments and commercial space in the near future.