Geothermal Load Calculation

What is a Geothermal Load Calculation?

A proper geothermal load calculation is the "foundation" of the system design procedure. Each home has a unique set of heating and cooling loads and is most commonly expressed in "Tons" to a homeowner. These loads are determined by local weather patterns, the architectural features of the home, the materials and techniques used to build the structure, the type of appliances and the number of occupants.

It is required for a professional that is experienced in determining the geothermal load calculation for a home to calculate the tonnage required for your residence.

Using general rules of thumb or simply making accidental errors in a load calculation can filter through the entire design of the system. These errors can cause discomfort during normal weather conditions, reduce the equipment's ability to control indoor humidity or temperature, increase operating cost, and reduce system efficiency and life expectancy. Additionally it may translate to larger equipment sizing, larger duct airways, and higher installation costs.

Site Visit

Whether your building a new home or retrofitting your existing home reviewing a set of plans, or the site, is essential for Comfortworks to determine the unique loads for your residence. This is also a great time to ask questions about the system, express your expectations of temperature control, operating costs, or design layout.


It is important as a homeowner to also understand that a geothermal heating and cooling system will both heat and cool the home. There is both a heating load and a cooling load for every home. When sizing these systems it is critical to ensure that it will both handle the heating load and cooling load for the home. Many dealers will install electric backup heat strips, or even a duel fuel system in combination with the geothermal system, but may miscalculate the heating load for the home which results in unwanted supplemental heating and high operating costs. After all, you installed this ground loop in the earth for a reason, so ensuring the geothermal system will fully heat and cool the home will maximize the efficiency of the system and significantly reduce operating costs.

Design temperatures of the homeowners expectations are critical when designing a system. Ideally, a thermostat setting of 75 degrees in the summer and 72 degrees in the winter will promote maximum efficiency. In reality, homeowners may desire colder temperatures in the summer or warmer temperatures in the winter. Informing Comfortworks of your expectations will ensure a properly sized system for your home.

Insulation directly effects the heat and air system and its ability to heat and cool the home efficiently and should be of high importance when building or upgrading a home. Lastly, items such as windows, doors, home direction, may have a profound effect on the system and the homes overall comfort, but the benefits need to be calculated. Comfortworks can calculate any building material type into the load calculation for a homeowner to compare its effect on the home and system. In turn, you will find where your money is best spent in your home to achieve a highly energy efficient system at the lowest possible installation cost and calculate the time of payback for these energy efficient upgrades.

Next, the cost of these upgrades needs to be taken into consideration. There is a line to draw between the cost of the upgrade and the benefit or payback of installing that upgrade. By far the greatest impact in any home will be installing a geothermal system. Over 60% of a homes energy use is in the heat and air system.

The materials & techniques used to build a home directly affect the load calculation and required tonnage. Spray foam insulation is a fantastic way of reducing the required tonnage and is explained in the next section. Additionally, items to consider are window types, door types, and the direction the home faces. Using low-e windows can significantly reduce the required cooling load. Insulated doors that lead to the outside or garage areas. Also, if it is possible, face the home in a manner to reduce windows in the south and west exposures to reduce load.

Benefits of Geothermal Load Calculation

An accurate and aggressive load calculation from Comfortworks will provide comfort and humidity control at design conditions, reduce the possibility of indoor mold and mildew, ensure proper system sizing, optimize installation costs, reduce operating costs, improve reliability, and maximize life expectancy.