How Energy Efficient Are Heat Pumps?
Heat pumps are more energy-efficient compared to air conditioners and furnaces. Instead of generating heat from fossil fuels, heat pumps move heat. You can use them to heat and cool your home.
What Is Efficiency?
The efficiency of heat pumps is dependent on how hard they work to keep a home cool or warm. Efficiency is a measure of the amount of energy a device delivers to your home compared to the amount of energy it consumes. The most efficient systems deliver many times over the amount of energy they consume.
Furnaces and boilers generate energy from burning fossil fuels. These systems have an efficiency that ranges between 78-98%. A heat pump uses electricity instead of fossil fuels. Even then, it is more efficient than other heating and cooling systems that use electricity.
Electric heaters and toasters are 100% efficient. This means they generate as much heat as the energy they consume. A heat pump, on the other hand, delivers up to 300% of energy. You can experience higher efficiencies with ground-source heat pumps, which rely on the constant temperature beneath the earth surface.
Why Are Heat Pumps So Efficient?
Instead of generating heat, heat pumps absorb heat from the air outdoor or underground and deliver it to the house. Heat pumps also collect waste heat from its own fans and circulates it back into your home.
The efficiency of a heat pump is dependent on the cost of fossil fuels vis a vis that of electricity. For instance, Americans prefer a heat pump that uses electricity to a furnace that relies on oil or propane. The cost of these fossil fuels is high in the U.S. However, natural gas is relatively cheaper, and some Americans might go for a furnace that burns natural gas compared to an electric heat pump.
In areas where the cost of electricity is low, a heat pump is a good alternative. Better yet, there are geothermal and solar-powered heat pumps that are even more efficient in the transfer of energy from outside the house to indoors.
Heat Pump Efficiency Grading
Because heat pumps heat and cool your house, they have two separate efficiency ratings. Manufacturers use different metrics to rate residential heat pumps.
SEER (Seasonal Energy Efficiency Rating) refers to the efficiency of a heat pump when in cooling mode. A higher SEER rating shows that a system is highly efficient. The SEER rating considers the amount of heat the pump removes from your home and divides that by the duration the system worked during the cooling season. To get the ratings correct, the system considers changes in temperature throughout the cooling period.
According to the Department of Energy, the minimum SEER rating for the heat pumps is 14. Some of the Energy Star-rated heat pumps have a SEER of up to 27.5. Any heat pump with a SEER of at least 18 is highly efficient.
HSPF ratings are a measure of the heat pump’s efficiency during the heating season. Short for Heating Seasonal Performance Factor, HSPF denotes the amount of heat a pump transfers to your home compared to the amount of electricity it consumes. A high HSPF means more efficiency.
To calculate HSPF accurately, manufacturers consider the changes in outdoor temperature. The Department of Energy recommends 8.2 HSPF as the least efficient rating for heat pumps. Most Energy Star-rated heat pumps have an HSPF rating of between 10 and 13.
Geothermal Heat Pumps Efficiency Ratings
Geothermal heat pumps are more efficient than air-source heat pumps. Instead of relying on the air outside your home whose temperature fluctuates, these heat pumps rely on the temperature underground, which is fairly constant. These heat pumps have different efficiency ratings from the typical heat source pumps.
EER (Energy Efficiency Ratio) refers to the efficiency of geothermal heat pumps during the cooling season. It’s almost the same as the SEER Rating of air source heat pumps, but the rating is at a specific temperature and not varying temperatures.
COP (Coefficient of Performance) is the efficiency of geothermal heat pumps during the heating season. It’s the same as HSPF but measured at a specific temperature. COP ratings use a fixed temperature to give the rating. The ground or water temperature doesn’t fluctuate; COP is, therefore, a more accurate rating of the system’s efficiency.
The Department of Energy recommends 16.1 EER as the minimum cooling efficiency for geothermal heat pumps. Some systems offer an EER of 30 or more, making them highly efficient. For COP, the Department of Energy recommends a rating of 3.1. Some systems have a COP of 4.5 or more.
Factors That Influence the Efficiency of a Heat Pump
The Department of Energy estimates that heat pumps can reduce the consumption of electricity at home by more than 50%. Heat pumps draw their energy from different sources with each type of heat pump having its advantages.
Air source heat pumps transfer heat from outside your home during the heating system. They draw power from electricity. There are split-system heat pumps that consist of a unit inside the home and another outside the home. If you need an affordable heat pump, this will meet your needs, but it is less efficient compared to a geothermal heat pump.
Mini-split ductless heap pumps draw power from electricity. These systems also draw heat from the outdoor air and transfer it into your home. They are mostly ideal when you need to heat a single space.
Geothermal heat pumps are the most efficient as they draw heat either from the ground or from water. These heat sources are fairly constant. Geothermal ground-source heat pumps transfer heat to or from the ground and to or from your house, depending on the season. Although these systems have a high efficiency, they are relatively expensive to install.
Geothermal water source heat pumps transfer heat to or from a water source. Like the ground-source heat pumps, these systems are also more expensive to install. Again, you need a water source near you.
Regional Climate and Heat Pump Efficiency
Heat pumps are more efficient in areas where temperatures are moderate. In areas where the temperatures are very low in winter, say as low as 25 degrees Fahrenheit, the heat pump will work harder to maintain comfortable indoor temperatures. As the heat pump works more, it consumes more electricity. When the temperature drops lower than 25 degrees Fahrenheit, you may need a supplemental heat source in your home.
The heat pumps also work harder when temperatures are very hot outside. However, the system is more efficient in a humid room as it dehumidifies the air.
You need to consider sizing when shopping for a heat pump. An undersized heat pump will not effectively heat or cool your room. On the other hand, an oversized system will be less efficient. Again, when the system is larger than needed, it heats or cools a room very fast and switches off. The on and off operation will affect the performance of the system.
Call Brennan Heating & Air Conditioning Today!
Sizing is best left to our professionals. At Brennan Heating & Air Conditioning, we offer heating, cooling, electric and duct cleaning services to residents in Seattle and the surrounding areas. We also have products such as ductless systems and hydronic heating systems. Call our professionals today for the best home heating and cooling solutions.