Geo-exchange Technology

Low-cost Renewable Energy for Heating and Cooling

Geothermal heat pump systems are among the most efficient heating and cooling systems available. According to the International Ground Source Heat Pump Association, they can reduce energy consumption by up to 50% when compared to conventional systems.

Heat from the sun warms the earth and keeps the underground temperature relatively constant throughout the year. A geothermal heat pump system takes advantage of this ground temperature, providing free, renewable energy for heating, cooling and domestic hot water.

RAUGEO is a system of piping placed underground that captures the earth's energy. This system works well on its own or, for optimal efficiency, when used in tandem with our radiant heating and cooling systems.

How it Works

Unlike outdoor temperatures that fluctuate with the changing seasons, the temperature of the soil four to six feet beneath the ground remains relatively consistent year-round for a given location. A ground source or earth energy geothermal system taps into earth’s natural heating and cooling properties through an underground loop heat exchanger system connected to an electric heat pump within your home or business.

Energy Transfer – From the Ground to Your Heat Pump

In the winter, a fluid  with antifreeze and water circulating through the ground loop system absorbs stored heat from the ground and carries it indoors. The heat pump, using the same refrigeration principle as your refrigerator, then compresses the heat to a higher temperature for  distribution  throughout the building. In the summer, the heat pump works in reverse, drawing heat from the building and carrying it through the loop system for rejection back into the earth.

Hydronic System Maximizes Energy Efficiency

Unlike conventional systems, geothermal systems don’t use burn  fossil fuels (natural gas, oil, propane) to generate heat. They simply exchange heat to and from the ground, depending on the conditions. Electricity is  used to operate the heat pump’s compressor, a circulating pump for the fluid in the ground loops and the electronics.


Components of the RAUGEO system:

1. RAUGEO U-bend vertical ground loop
2. RAUGEO Collect horizontal ground loop
3. Balancing manifold
4. Geothermal heat pump
5. Radiant heating and cooling distribution piping system

Benefits

Supplies Energy Efficiently

In heating mode, a geothermal system can be three-to-four-times as efficient as the most efficient conventional system. Because geothermal systems do not burn fossil fuel (i.e. gas, oil, propane) to make heat, they provide three to four units of energy for every one unit used to power the system, through electricity. In cooling mode, geothermal systems can be two- to three-times more efficient than traditional air conditioners or air-to-air heat pumps. This improved efficiency translates directly to reduced operating costs.

Reduces Maintenance Costs

Closed-loop geothermal systems are practically maintenance-free. When installed properly, the buried ground loop of crosslinked polyethylene piping will last for generations. And the other half of the operation-the heat pump’s compressor and circulating pump-is housed indoors, protected from the harsh weather conditions. Usually, periodic checks and air filter changes (for forced air distribution) are the only required maintenance.

Minimizes Environmental Impact
A ground source heat pump system can reduce energy consumption by up to 50% as compared to conventional systems, according to the International Ground Source Heat Pump Association.  In addition, a typical residential system reduces carbon dioxide emissions by more than 200 tons over a 20-year period, which is equivalent to removing two cars from the road.

Installation

A closed loop system is the most common type of geothermal system installation. The term "closed loop" is used to describe a geothermal heat pump system that uses a continuous loop of special buried plastic pipe as a heat exchanger.  The pipe is then connected to the indoor heat pump to form a sealed, underground loop through which an antifreeze solution is circulated. 

During system operation, fluid constantly circulates in buried pipes/loops, absorbing stored heat from the earth during the winter months and carrying it indoors and taking heat from indoors and rejecting it back into the earth during summer.

There are several loop configurations available for closed loop systems:

RAUGEO U-bend Vertical Ground Loop

Where space is limited and energy demand is significant, such as in most commercial applications, vertical ground loops are inserted in boreholes which are several hundred feet deep using a well-drilling rig. The RAUGEO double U-bend design requires up to 30 percent less borehole footage than a single HDPE U-bend. 

RAUGEO Collect Horizontal  Ground Loop

Where there is plenty of open space and suitable soil conditions, ground loops can be installed in long horizontal trenches about 5 to 7 ft (1.5 to 2 m) below ground.  This method requires more available land than other installation methods and can cause a disturbance to lawns and landscaping, but is the most economical option from an installation cost standpoint.

Projects


Arcadia University (Glenside, PA)

The Commons at Arcadia University is a 62,000 ft2 (5,760 m2) addition featuring student lounges, activity and dining areas and flexible meeting rooms. The Commons was designed with several energy-saving elements including both solar and geothermal systems to provide sustainable, renewable energy sources. While original specifications for the geothermal piping system called for traditional HDPE ground loops, Arcadia University was encouraged to switch from HDPE to RAUGEO PEXa pipe from REHAU. 

Download the PDF


Biohaus Environmental Living (Bemidji, MN)

The Waldsee BioHaus in Bemidji, MN is the first certified German Passivhaus in North America. The educational facility provides a level of energy efficiency beyond that of the US Green Building Council’s LEED standard, using 85 percent less energy than comparable US structures. Geo-exchange technology from REHAU is among the numerous innovative energy saving systems incorporated into the structure's design.

Download the PDF


Drake Landing Solar Community (Alberta, Canada)

The first community of its kind in North America, Drake Landing is modeled after a proven European technology known as "solar seasonal storage." Each home is heated by a system designed to store an abundance of solar energy underground during the summer months and redistribute the energy throughout the winter, fulfilling 90 percent of each home's space heating requirements. The solar energy system is composed of an array of 800 flat plat solar collectors and the RAUGEO geothermal heat exchange system, which includes high-pressure cross-linked polyethylene (PEXa) pipes from REHAU.

Download the PDF


Minnie Howard School (Alexandria, VA)

The renovation of this 54-year old school incorporated REHAU Geo-exchange technology in combination with solar technologies to cut natural gas consumption by 66%. The well field for the RAUGEOTM ground loop heat exchange system features 65 boreholes reaching 300 ft (90 m) deep to tap into the earth's natural energy for heating and cooling the school. In each borehole, REHAU PEXa pipe is fitted with RAUGEO Double U-bends for greater energy extraction. The RAUGEO system is anticipated to contribute to $400,000 life cycle cost savings over the next 20 years, as well as reduce greenhouse gases by 110,000 lbs of CO2 per year.

Download the PDF


Old Town Alexandria Residence (Alexandria, VA)

Retrofitting this historic home with a geothermal system presented a unique challenge for the owners and contractors. Typical boreholes for the ground loops require 20-foot spacing, but the backyard space wasn't big enough for the number of wells needed to accommodate the system's Btu requirements. The solution was found in the RAUGEO™ PEX-based ground source heat exchange system from REHAU, which includes double U-bends that collect of up to 30 percent more energy per borehole. 

Read More  Download the PDF


Village Green Homes (Loudoun County, VA)

When Robert Lauten, of Lauten Construction, wanted to incorporate technologies that would make his homes the first in Loudoun County to meet the US Green Building Council’s LEED standard, he turned to REHAU. Bringing REHAU’s leading edge heating and cooling systems into the design for his traditionally sized homes enabled Lauten to capitalize on a ground loop heat exchange system that has the potential to deliver 9 million Btu’s of energy, per year, to its eventual homeowners. This would offer a carbon offset of almost 3 million metric tons, compared to a traditional energy source.

Read More  Download the PDF

Whisper Valley Entrance

Whisper Valley Net-Zero Capable Community (Austin, TX)
One of the ten biggest developments of its kind in the US, this sustainable, master-planned community features 7,500 Net-Zero ready homes. All structures will be geothermal and solar equipped, capable of achieving the Net-Zero energy (or carbon neutral) standard adopted by the City of Austin’s Municipal Building Code for all new construction homes. Homeowners incur no upfront costs for the geothermal system, as the ground loop infrastructure is pre-installed throughout the community.

Read More  Download the PDF

Media & Tools

Tax Incentives
Commercial project owners can take advantage of a 10% uncapped U.S. federal tax credit as well as an accelerated depreciation schedule (5 years vs the typical 25+ years), with 50% taken in year 1. Consult your tax adviser.

REHAU RAUGEOTM Geothermal Ground Loop Wins Alternative Energy Product Innovation Award