Geothermal Heat Pumps Provide Sustainable Alternative for Architects

by Russell Boniface
Associate Editor

How do you . . . use the constant temperatures below ground to create an active, cost-efficient solar heating and cooling device for a home or business?

Summary: Direct exchange geothermal heat pumps are an efficient, sensible form of renewable energy, says Peter Gumpert, vice president and chief operating officer of Brookline, Mass.-based EarthSource Energy Solutions, Inc. The firm manufactures the EarthSource Geo Direct™ line of direct exchange geothermal heat pumps that heat and cool a home or business without burning gas, oil, or other fossil fuels. They also provide low-cost domestic hot water. Gumpert believes that architects should increase their awareness of this renewable energy technology, which he says can save home and business owners 40-70 percent in heating, cooling, and water heating costs. A geothermal heat pump is small enough to fit into a closet, and its technology simply requires inserting copper loops underground.

Tapping the stored solar energy in the ground
Direct exchange geothermal heat pumps do not involve water pumps or deep drilling, and require little land to install. Geothermal heat pumps work because the ground below the surface remains at a relatively constant temperature throughout the year, like a cave. The geothermal pumps transfer this energy into a building for heating and cooling.

“The pumps are called direct exchange because the exchange is not through an intermediate water source but through copper pipes in the ground that carry refrigerant directly from the ground to the building,” says Gumpert. “It works exactly the same as a refrigerator, which is a heat pump. In the summertime, our device dumps heat from the building to the ground, and in the wintertime it picks up heat from the ground. Essentially it’s a reversing system. The device is picking up the ground’s solar energy. It’s always operating in the range of peak efficiency, so it doesn’t have to heat zero-degree air or cool down 100-degree air. No fossil fuels are burned. We are just taking advantage of the fact that the Earth stores huge amounts of energy.”

Heat pumps for this kind of application are approximately a two-foot cube. “The heat pump itself fits easily into a utility closet and is very quiet,” says Gumpert. A compressor in the heat pump compresses and expands the refrigerant, and un-needed heat is used for domestic hot water. The copper pipes, or loops, are installed in the ground. In vertical installations, the copper loops are inserted 55 feet in boreholes 3-4 inches in diameter, then the copper loops are surrounded by conductive grout. The copper loops can also be installed diagonally and horizontally, where a pit is excavated for the loops, which are then protected by finely ground stone.

Gumpert says the technology dates back to the 1940s, but is not well known among architects. “It’s been improved over the years, but never as well known as the water-source heat-pump technology, which architects know more about. Geothermal heat pumps reduce the cost of heating, cooling, and hot water. The reason is that three-quarters of the energy that you are using to heat the house already exists in the ground. The device is bringing that energy up or sending it down.”

Increasing awareness
Gumpert believes architects should increase their awareness of geothermal heat pumps but points out that the problem for architects and developers has been cost. “There is a greater upfront cost, but once a home- or business owner makes the initial investment, they reap immediate lifelong benefits. The systems don’t have to be replaced and can last indefinitely. The homeowner begins to reap the rewards because heating, cooling, and hot water costs are reduced 40 to 70 percent. The architect’s responsibility is greatest in respect to people with more modest means who are being affected by unstable fossil fuel prices.” Gumpert adds that the devices can also reduce greenhouse gas emissions.

“From an architect's point of view,” he adds, “the aesthetic advantage of geothermal heat pumps is that it doesn’t compromise the look of a building like a roof full of solar panels, or a lifestyle, such as the requisite changes in temperature for a passive solar house.”

It would make sense, Gumpert says, for architects, builders, and banks to form partnerships to provide durable and affordable homes and office buildings. “Due to an increase in mortgage payments and a slumping economy, heating costs have at least doubled in the past few years. If we are going to design and build affordable houses and encourage people to purchase and live in them, we owe it to them to include solutions that mitigate economic instability as much as possible.