COP and EER: How Geothermal System Efficiency Is Measured
Geothermal system efficiency is one of the first things to get acquainted with if you’re planning on installing a geothermal system in your Delaware home. Understanding efficiency ratings makes it easier to compare systems and find the ones that will lower your energy bills the most.
Coefficient of performance (COP) — This rating indicates a system’s heating efficiency. The higher the COP, the more efficiently the system heats. The rating is a ratio of heat produced (in Btu per hour) over electrical energy input. Simply stated, it indicates how much home heating you get for the amount of electrical energy the system uses to concentrate that heat. Geothermal heat pumps typically have COPs of 3 to 5.
Energy efficiency ratio (EER) — This number indicates a system’s cooling efficiency. A higher number means greater efficiency. The number is a ratio of the heat removed from your home (in Btu per hour) over the amount of electricity (in watts) the system uses. The average geothermal system has an EER of between 13 and 18. Although geothermal system efficiency is higher than that of most conventional heating and cooling systems, it’s still worth looking for the most efficient model among the geothermal systems available.
To enjoy the greatest efficiency and take advantage of the 30 percent federal tax credit for new installations, look for an Energy Star-qualified geothermal system. To qualify, a closed-loop water-to-air system, which uses sealed pipes buried in the ground, should have a COP of at least 3.6 and an EER of at least 17.1. An open-loop water-to-air system, which uses open pipes in water, should have a COP of 4.1 or higher and an EER of 21.1 or higher. Differences in testing criteria make it difficult to accurately compare efficiency ratings across different system types, such as air-source (conventional) and geothermal heat pumps, so consult a professional for guidance.
For help choosing the most efficient heating and cooling system for your home, contact us at Sobieski Services. Our goal is to help educate our customers in Delaware, Pennsylvania, Maryland and New Jersey about energy and home comfort issues (specific to HVAC & plumbing systems).
Image Credit: kevin.pelrine