By: Justine Bula
A top priority for Madison resident Eric Suomi is reducing his carbon emissions and doing his part to address climate change. With a background in electronics engineering, Eric always considers what problems can be solved and what the trade-offs are for different solutions.
Following retirement in 2019, Eric decided to focus on home energy efficiency and electrification projects. His first project was replacing incandescent and flourescent lights with LEDs. Next, he added solar panels to charge his electric Nissan Leaf vehicle so that it runs on clean energy. Then Eric began looking for ways to reduce the amount of natural gas used in his house and started looking into upgrading his heating system.
Eric’s cousin in Minnesota had installed a geothermal heat pump system on his farm, so Eric began looking into options for his home in Madison. Heat pumps work by moving heat from one place to another, instead of generating it, to heat or cool your home. There are different kinds of heat pump systems, including ground source (geothermal), air source, absorption heat pumps (gas-fired), and more. Cold-climate heat pumps (a type of air-source heat pump designed for colder climates) and dual-fuel heat pumps (where there is a heat pump coupled with a natural gas backup system) are the most common types of heat pumps for Wisconsin residents. For decades, though, some homeowners have opted for geothermal systems.
Geothermal heat pumps are considered to be renewable energy because they take advantage of the relatively constant underground temperatures, which ranges from 40 to 70 degrees Fahrenheit. Because of the relatively constant underground temperatures, geothermal heat pumps are more efficient at heating and cooling than cold-climate heat pumps.
The timing for the project worked out great as Eric’s 30+ year old air conditioner and furnace systems were due for a replacement, and the IRA tax credit provided a 30% federal tax credit on the total cost of the new geothermal heat pump system. In addition to the federal IRA tax credits, Eric’s home is located in a national historic district, making it eligible for an additional state tax credit of 25% of the project’s cost. Eric's project was also eligible for a $1,100 rebate through Focus on Energy. With these incentives, the project was more affordable and Eric began to search for an installer.
This step proved challenging, as the geothermal heat pump system that Eric was installing needed to be vertical due to space constraints. Eric's backyard was not large enough for the horizontal heat exchange loop field that his cousin was able to install on his farm in Minnesota. Vertical loop fields are necessary with small spaces but cost 2-3 times more than horizontal loop fields.
Eric eventually found G.O. Loop out of Fox Lake, who could set up the vertical bores in the front yard, which was more accessible for the large drilling equipment needed. G.O. Loop also installed the loop connection from the bores into the basement, then to the flow 
center, and the final loop filling once all the piping was complete. An additional contractor, Pharo Heating from Waunakee, then installed a split dual-fuel system, furnace, geothermal heat pump unit, flow center, and finally connected the flow center to the heat pump unit.
An important note Eric learned through the installation process was understanding your bedrock. For Eric's project, the drilling went through primarily sandstone, making the process faster than anticipated. However, as he learned from the installers, in some areas around Wisconsin where drilling takes place through loose limestone, the bores have the potential to collapse when the drill is removed. Eric waited to order his heat pump until they knew how the drilling would work out, which led to a delay but prevented possible investment in a unit that would not be usable if the required bore did not work.
Once the drilling was complete (225 feet down!), the two vertical loop bores were filled with looping pipe and bentonite, a fine volcanic ash that helps with thermal conductivity. The piping connects to the basement flow center, which includes the heat pumps.
The new geothermal heat pump faced another challenge a few months after being installed; a subzero cold spell that the new heat pump could not keep up with. But, because Eric went with a dual-fuel system that can use the geothermal-powered heat pump or natural gas furnace when needed, the system switched to gas for heating during the severe cold spell. However, in the long-term Eric needed to address the lack of insulation in his house's walls to decrease his monthly energy use and eliminate the need for a back-up system during future cold spells. With new foam insulation, Eric saw an energy use reduction of around 25% using the energy consumption monitor in his smart thermostat.
The next project in the pursuit of energy efficiency was to replace the aging conventional gas water heater with a heat pump water heater that could connect to the geothermal heat pump.
The geothermal system increases Eric’s electric consumption while reducing his use of natural gas; coupled with his solar (that also powers his car) Eric is seeing a reduction in total energy costs.
Like Eric, if you are considering investing in and upgrading to a new, more efficient system, there are imp
ortant factors to consider, including your priorities. Whether your focus is on maximizing energy efficiency or saving money and decreasing your monthly utility bill, there are options for you.
A primary consideration for whether residential geothermal is right for a homeowner vs. an air-source heat pump is yard space. Eric went with a vertical geothermal system to address space constraints, but the system still requires borings on your property. Vertical systems are more energy efficient but come at a higher cost.
Check out Focus on Energy’s Heat Pump page as well as their Guide to Heat Pumps, which includes tips for choosing the right heat pump. The U.S. Department of Energy also has helpful information and resources to find which system might work best for you and your home, although their information is not specific to Wisconsin. In terms of cost, prices can range anywhere from $12,000 - $45,000 for a geothermal heat pump system, depending on factors like the size of the system, property location, and complexity of the installation. An important note is that with a heat pump, you are getting two appliances in one since heat pumps are capable of both heating and cooling. Other important considerations include finding contractors and installers to do the job. If you’re interested in scoping a project for your home, use the Focus on Energy Trade Ally Contractor resource to help get started and find contractors and check out the Home Energy Rebates resource for a list of local IRA registered contractors who can help you with IRA Home Energy Rebates.
Eric is continuing to explore projects that will increase his resilience and reduce his greenhouse gas emissions.
Actions and investments in our homes and communities can go a long way toward reducing emissions. So, when the time comes to replace your old furnace, A/C unit, or even light bulbs, consider investing in a replacement that will increase energy efficiency, reduce emissions, and save money in the long term. If you don't know where to start, check out our Home Electrification webpage for ideas and resources to help you get started.
