One of the most common misconceptions about a geothermal system in Northern climates is that a backup is required and costs a lot to operate. This amazing technology can be designed so no backup heat at all is required, also known as “full load heating design”. The unparalleled operating efficiency and heating output of this renewable energy technology is why geothermal costs the least to operate and can take care of any home without help.
Eliminating Backup Heat
Geothermal systems can be designed to require no backup, even during the coldest temperatures. Geothermal professionals will utilize a heat loss analysis and system modeling to confirm your geothermal package will not require backup heating. This model will also estimate the operating costs throughout the year, comparing different system types.
Older geothermal designs would purposely specify backup heat to be used during peak conditions (coldest days) since the equipment was not able to be sized for the full heating load due to the problems with cooling and humidity control. These systems would be able to handle approximately 90% of the heating load and utilize auxiliary heating to supplement during the lowest winter temperatures. Operating the auxiliary heater uses significantly more energy and should only be used sparingly.
Exceptions
There are still cases where a backup heat source is purposely designed for use during extreme conditions. For example, a single geothermal system may only be able to handle 97% of the heating load for a larger home, resulting in approximately $200 per year in additional cost to run the backup heater. The system designer could specify two geothermal units to increase the capacity to 100%, however, the upfront cost increases by $20,000, resulting in a long payback for the extra unit. The auxiliary heater operating cost modeled to operate during extreme conditions is minimal in this case and may be the best choice for this home.
Modern geothermal design, improved installation techniques and technological advancements have made full load heating possible, offering the lowest operating costs possible for a heating and cooling system. Make sure your geothermal installer is modeling your unique home and considering full heating load system design.