If you’re planning on replacing a central air conditioner or heat pump, one of the most important things you should focus on when choosing a new unit is SEER ratings. SEER stands for Seasonal Energy Efficiency Ratio, and the SEER rating of any central cooling unit tells you how efficient it is and approximately how much energy it uses. In this guide, we’ll explain how SEER ratings are calculated, what they mean, and how they can help when deciding which new AC or heat pump is the best option.
How SEER Ratings Are Calculated
SEER is just a ratio of how much energy an air conditioner or heat pump uses compared to how many BTUs of cooling it provides. Calculating the SEER rating of any cooling unit is simple. All you need to do is divide the BTUs of cooling it produces per hour by the watt-hours of electricity it consumes. The higher this ratio is, the more energy-efficient the unit is.
However, the only way to determine both of these numbers is to test the unit to see how efficiently it performs in various conditions. The reason that these tests are necessary is that the efficiency and effectiveness of any cooling unit that sits outdoors can fluctuate a lot depending on both the indoor and outdoor air temperature and humidity level. The efficiency of a window or portable air conditioner doesn’t change that much since these units sit inside where they generally aren’t exposed to as high of heat. However, outdoor cooling units are directly affected by heat and humidity. In hotter, more humid conditions, an air conditioner or heat pump won’t work as effectively as it does in less hot, less humid conditions.
High heat and humidity make it more difficult for the unit to release the heat it removed from inside. This leads to the refrigerant staying slightly warmer, which means it can’t capture as much heat from the warm air circulating through the system. As a result, the rate of cooling slows down, leading to longer cooling cycles and increased energy consumption. Indoor temperature and humidity also matter. AC systems work more efficiently when the air indoors is drier and the temperature of the air coming into the system is only slightly above the desired temperature.
These issues mean that it is impossible to accurately calculate the energy efficiency of a central AC or heat pump just by looking at one hour or even one day or week. Instead, SEER looks at the average efficiency throughout a typical 1,000-hour cooling season.
Comparing SEER and SEER2
At the start of 2023, the US Department of Energy switched from the original SEER ratings to the new SEER2 rating system. The difference between the two is in the testing parameters, as SEER2 was designed to be more accurate and better reflect real-world operating conditions. Specifically, the SEER2 tests run units in a system with slightly higher static pressure than was used in the SEER tests.
Static pressure refers to the amount of resistance to airflow there is in a ducted, central HVAC system. The majority of homes have various issues that contribute to higher static pressure, such as old or leaky ducts, dirty air filters, etc. High static pressure leads to a decrease in the volume of air the system can circulate per minute. This in turn leads to the system not working quite as efficiently. The fact that most homes have issues with higher static pressure is why the testing requirements were changed. It’s also why SEER2 ratings are a more accurate reflection of a unit’s energy efficiency in the real world and not just in a lab setting.
You don’t necessarily need to fully understand the differences between the two ratings and tests. The most important thing to understand is that SEER and SEER2 are a way to compare the efficiency of various units. They also allow you to estimate how much any AC or heat pump would cost to operate over a full cooling season.
If you want to estimate the potential energy savings with a new unit compared to your existing unit, you can easily convert the SEER rating of your existing unit to SEER2. All you need to do is divide the unit’s SEER rating by 1.05 to find the SEER2 rating.
How to Use SEER Ratings When Choosing a New AC or Heat Pump
The US Department of Energy has minimum energy-efficiency requirements for all new central cooling units sold in this country. All split-system central ACs and heat pumps installed in California and throughout the Southeast and Southwest are required to be at least 14.3 SEER2, which is the equivalent of 15 SEER. The requirement for packaged ACs and heat pumps is 13.4 SEER2.
As SEER ratings increase, energy consumption decreases by approximately 7%. This means that a 16 SEER2 unit would use around 7% more energy than a 15 SEER2 unit. If your existing AC was installed between 2006 and the end of 2014, there is a chance it is only 13 SEER (12.4 SEER2). In this case, you would lower your cooling costs by around 15% if you upgraded to a 14.3 SEER2 unit. If you instead chose an 18 SEER2 unit, you’d end up saving around 45% a year. This type of calculation is helpful when deciding if it is worth it to upgrade a unit that is still working effectively or if you’re better off waiting until it starts to give out.
Comparing SEER2 ratings can also allow you to estimate the approximate lifetime energy usage and operating costs for various units, which is helpful when deciding if a higher-rated unit is worth the higher cost. Let’s say that you need a 5-ton AC or heat pump. In Orange County, a 14.3 SEER2 unit this size would typically cost you somewhere around $700-750 in electricity over an average year. If you went with a 5-ton 16 SEER2 unit, it would save you around 25% per year or around $750 over five years.
The average lifespan for a central AC is around 15 years, which means you’d likely end up saving over $2,000 over the life of your new AC if you opted for the higher-rated unit. If you instead chose to install a 24 SEER2 unit, you’d end up saving well over $4,000 over its 15-year lifespan compared to using a 14.3 SEER2 unit.
Performing this type of calculation makes it easy to strike a balance between the upfront cost of a new unit and its total lifetime operating costs. While the most basic 14.3 SEER2 unit will always be the least expensive to install, it will also cost the most to operate. The price difference between a 14.3 SEER2 and a 16 SEER2 unit will typically be under $2,000. Since the higher-rated unit would likely save you over $2,000 over its life, it will be the less expensive long-term option and the better choice. However, it doesn’t always make sense to install the highest SEER2 unit available since the amount you’d save on energy costs may never outweigh the higher initial cost.
At White Mechanical, Inc., we offer professional cooling and heating installation services for residential and commercial customers in Foothill Ranch and throughout Orange County. We carry an extensive selection of energy-efficient central and ductless air conditioners, heat pumps, and furnaces from trusted brands like Lennox. We also offer expert HVAC maintenance and repairs, and our certified technicians work on all makes and models of HVAC equipment. If you have any questions about SEER ratings or want to schedule a consultation to find the right unit for your home or business, give us a call today.
