ACHRNEWS

Going Geothermal and Earning Platinum Status

November 10, 2008
For the Sustainable Home, four wells were drilled to a depth of 135 feet and a WaterFurnace geothermal system was installed. The system uses the Earth’s stable temperatures to provide heating and cooling for the house and even the heating for the water heater. (Feature photos courtesy of LiveGreen LiveSmart.)

Visitors to Live Green Live Smart’s The Sustainable House™ will see a number of green building materials and techniques as they tour the home. Inside, the long list includes energy-efficient, compact fluorescent light bulbs, Energy Star appliances, recycled cabinetry and countertops, and automatic on-off faucets with batteries that recharge as water flows up and out.

Outside the remodeled 1948 rambler, rain gardens planted with native plants collect rainwater and allow percolation back into the ground. Native plants requiring less water are established, and hardscapes are paved with permeable materials to reduce runoff.

What visitors to the over $1 million property won’t see are the four 135-foot-deep geothermal wells and the vertical loop system used to provide heat to the home in the winter and air conditioning in the summer.



LEED-ING THE WAY

The Sustainable House in Minnetonka, Minn., is the first remodel to achieve the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) Platinum certification, the highest LEED certification for conservation and renewable energy in home building. The house is also the first to achieve Minnesota’s GreenStar Gold certification, the highest level possible for this green standard as well.

Remodeled as an educational demonstration of green remodeling standards, technologies, and long-term durability, the house was one of more than 120 structures that were screened for the project by Live Green Live Smart, an environmental educational organization, which states it is “dedicated to promoting a sustainable planet through education, linking of resources, and fostering a global green community.”

During the remodel, the interior of the house was stripped to the studs, leaving behind an uncluttered framework in which homeowner and Live Green Live Smart Executive Director Peter Lytle could incorporate systems and materials that offered energy efficiency, water conservation, habitat protection, resource efficiency, and healthy occupancy.

Whenever possible, materials that were removed from the home were recycled into the remodel or other building projects. As building materials were removed, so were plumbing and electrical systems, ductwork, and the home’s furnace and air conditioning system.

In place of the traditional home comfort system, Lytle opted for a geothermal system capable of heating and cooling the 2,300-square-foot home efficiently and in an environmentally friendly way.



Front exterior view of the Sustainable House in Minnetonka, Minn., the first remodel to achieve the USGBC’s LEED Platinum certification, the highest for conservation and renewable energy in home building.

GEOTHERMAL IS THE WAY

A geothermal system is designed to tap into the constant moderate temperatures found a few feet below the surface of the earth. According to Lytle, a series of pipes (an earth loop) buried in the ground “carry an environmentally friendly mixture of alcohol and water solution.”

During the heating mode, Lytle said this fluid circulates through the pipe where heat energy is transferred from the ground (the heat source) to the fluid and then to the geothermal unit. In this case, the parties involved opted for an Envision Series unit from WaterFurnace (Fort Wayne, Ind.). The unit, located in the home, provides warm comfort to the structure, said Lytle. And inside the home, the heat can be distributed through either a conventional duct system or a hydronic radiant heat system, he added.

To provide air conditioning, the process reverses, he explained. Heat is removed from the home and transferred to the loop fluid. As the warm fluid travels through the pipe in the earth, it is cooled. In the cooling mode, the earth serves as, to put it in Lytle’s words, a “heat sink.” In other words, it is a place to deposit the heat removed from the home.

In addition to earth loops, geothermal systems can also use a pond, or a lake as the heat source or heat sink to provide heating and cooling comfort for the home, explained Lytle.

As a bonus, a geothermal unit can provide some or all of a home’s hot water at higher efficiencies, offering additional energy savings. Using a simple connection to a water heater, the geothermal unit will deliver hot water to the tank during the heating and cooling modes. In fact, the heat removed from the home during cooling is deposited into the water heater to provide virtually free hot water, said Lytle.



BELIEVES IN THE (UNDERGROUND) SYSTEM

According to Jim Cusack, general manager at UMR Geothermal, the firm that installed the system at The Sustainable Home, a geothermal system offers the homeowner numerous benefits, beginning with significantly lower operating costs when compared to a traditional home comfort system.

“A geothermal system operates more efficiently than an ordinary heating and air conditioning system because it can deliver an astounding four units of energy for every one unit of electrical used,” said Cusack. “That translates into an efficiency rating of 400 percent, compared to the most efficient gas furnace, which rates only 94 percent. By combining stored earth energy with safe electric power, many homeowners realize savings up to 70 percent on heating, cooling, and hot water.”

Cusack said the efficiency of the system and reduced energy costs typically offset the costs associated with the installation of a geothermal system. In new homes, most homeowners will experience an immediate positive return on investment when the system cost is added to the mortgage, he offered.

“In remodels, homeowners will find that any added investment over the cost of an ordinary system is generally recovered in energy savings within a few years,” said Cusack.

He also pointed to improved comfort levels as a benefit of a geothermal system.

“Conditioned air is provided at a more constant rate, eliminating hot and cold spots throughout the home thanks to two-stage heating and cooling,” said Cusack. “And maintenance is minimal. Systems do not need to be cleaned and checked like conventional furnaces and air conditioning units.”

Also important to this project is the fact that “geothermal systems reduce the carbon footprint by as much as 40 percent, even with the coal-fired power plants in Minnesota,” said Cusack. The system reduces carbon dioxide, carbon monoxide, and other greenhouse gas emissions, which are considered to be major contributors to environmental air pollution, he noted. In addition, dual systems, like the one installed at The Sustainable House, give power companies the flexibility to postpone construction of new power plants, he said.



ENERGY AND ENVIRONMENTAL SAVINGS

All parties agreed that the advantages of the unit in particular - and geothermal systems in general - played an important role in securing LEED Platinum status for The Sustainable House. The house needed to meet a rigorous set of guidelines that required exceptional attention and innovation on the part of builders and designers.

In the end, more than 250 people and seven teams of professionals carefully selected materials and technologies to meet stringent, but energy-efficient, guidelines. The parties involved combined to minimize the carbon footprint and preserve natural resources with as much energy independence as possible, in the process. The end result is a comfortable, sustainable home for the Lytles, and a laboratory for homeowners everywhere “that demonstrates and evaluates best practices in sustainability,” said Lytle.

For more information, visit www.livegreenlivesmart.org/about.aspx.



Sidebar: Breaking Down

Jim Cusack, general manager at UMR Geothermal, had more than a few positive comments to make regarding the Envision Series unit that anchors The Sustainable Home’s geothermal system.

“This particular unit offers the most energy-efficient, environmentally friendly system available, not just for this unique installation, but for any installation where the owner is looking to combine green technology with proven significant energy savings,” said Cusack.

According to the manufacturer, the Envision’s two-speed compressor unit, installed in Lytle’s home, features a Scroll UltraTech™ compressor which can reach a 4.3 coefficient of performance (COP) in heating and a 24.5 energy efficiency ratio (EER). WaterFurnace said certain models from its Envision Series are capable of reaching a 5.0 COP in heating and a 30 EER in cooling.

These ratings make the Envision Series the most efficient heating and cooling system ever rated by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI). The unit uses environmentally friendly and nonozone depleting R-410A refrigerant, designed to enhance efficiency and savings.

According to the manufacturer, the Envision unit also offers whisper-quiet operation and improved comfort. It said its ultraquiet scroll compressors are mounted on double-isolation plates made of acoustically treated metal and wrapped in a compressor blanket, all designed to reduce noise. In addition, two-speed compressor technology is designed to improve IAQ by allowing extended run times, said the manufacturer.

For additional information, visit www.waterfurnace.com.

Publication date: 11/10/2008