Can Geothermal work in Cold Climates like Wisconsin?

 In Geothermal Heating

We are often asked if Geothermal really works in our cold climate. This is usually said with one eyebrow raised since there certainly are many misconceptions and false information out on the internet including statements stating that Geothermal is not ideal or that the heat produced naturally cannot keep up with the cold Wisconsin winter. We are going to use some science mixed in with over a decade of Geothermal experience to answer these questions and put some of these notions to rest.

Let’s start with comparing the difference between air source heat pumps and geothermal heat pumps, where many of the problems in the comparisons stem from.

Air Source Heat Pumps VS Geothermal Heat Pumps

Although the names are similar , it certainly can be used incorrectly just by saying “Heat Pumps”, but we need to understand the main difference, which comes down to where the energy supply is coming from.

Air Source Heat Pump

An air source heat pump (ASHP) is a type of heating system which takes the heat from outside the home and transfers it to the inside of the home by means of a compressor and a condenser to absorb the heat at one place and release it at another. They can also be used as a space heater or cooler, and are sometimes called “reverse-cycle air conditioners”.

The principle is that air above absolute zero contains some energy, and like a refrigerator or freezer, heat is generated when trying to cool the warm air and vice versa.  In colder climates, users often need a secondary heat source to rely on as the temperature drops so low that it cannot harvest any heat from the air. Often this secondary heat source is electric heat, which makes the whole operation inefficient, especially as you start to compare the Coefficient or Performance (COP).

Ground Source Heat Pump

A geothermal heat pump or ground source heat pump (GSHP) is a central heating and/or cooling system that transfers heat to or from the ground.  It uses the earth as a heat source (in the winter) or a heat sink (in the summer). With Geothermal, the energy source is extracted from the temperature from deep in the ground, where it is a constant year-round temperature. Even when the outdoor temperature drops below zero, the ground temperature is still providing a heat source for the ground source heat pump. You never have to use a backup heat, which means a warmer house.

How to Properly Size Geothermal

Unlike traditional furnaces, where you size the unit larger than what you need, geothermal pumps are sized exactly for the size of the home and the lowest temperature of that area. This allows the pump to run at a constant to provide the heat needed on the coldest day of the year. This is what makes the Geothermal heat very efficient. Typically, electric power is used only to operate the unit’s fan, compressor and pump. Maybe this is why many people are confused as to the efficiency of Geothermal to regular furnaces. Homeowners are used to having their furnaces run less as they get more and more efficient, but this is not the case with Geothermal. Geothermal units are designed to run continuously, and they never loose efficiency.

What if Geothermal is Sized Incorrectly?

If sized incorrectly, a geothermal pump wouldn’t be able to keep up with the cold days of winter and a secondary heat source would be needed. This causes a higher utility bill and a colder home. Many installers and providers are guilty of under sizing the units which has tarnished the efficiency of Geothermal Heat Pumps and the industry as a whole. This is where many homeowners think that Geothermal is not right for our climate….from unhappy (and often cold) customers.

Geothermal is more of a fit to our climate than you would think. There are no moving parts on the exterior that can get damaged by storms or covered up with snow. They require low maintenance requirements and life expectancy can last over 20-years. It’s a renewable resource and lessons our dependence on fossil fuels. If sized correctly it can provide year-round heat that will never lose its efficiency.

If interested in gathering information on Geothermal Heating and installation, do not hesitate to contact us.


Pharo Heating & Cooling is a full-service HVAC contractor in Madison. Our team provides top quality service for new construction and replacement furnace and air conditioner needs. For more information about annual furnace inspection or concerns, give us a call at 608-849-5410 or submit a contact form through our website.

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