What Your A/C SEER Rating Actually Means
When an HVAC unit works efficiently, it will consume less energy as it makes your home feel comfortable. A factor that helps you determine an air conditioner’s efficiency is its Seasonal Energy Efficiency Ratio (SEER) rating. In general, the higher the rating, the more efficient the cooling equipment is. Each state has a minimum SEER rating standard for new air conditioning units, which is 13 or 14 SEER. Understanding what this rating means for you before an A/C installation will help you make an informed decision about the cooling unit that best meets your needs.
SEER ratings are ratios derived by calculating the annual cooling output during the cooling season divided by the total electric energy input. The total cooling output is the A/C’s British thermal unit per hour (BTU/h) multiplied by the number of cooling hours per day and the number of cooling days per year. For example:
6,000 BTU/h x 10 cooling hours per day x 200 days per year = 12,000,000 BTUs per year
Using the example above, if an air conditioner has a SEER rating of 15 BTU per watt-hour (Wh), you could calculate the estimated annual energy use as follows:
12,000,000 BTUs per year ÷ 15 BTU/Wh = 800,000 Wh per year
To calculate the annual average power use, divide the A/C’s BTU/h by the SEER rating. For example:
6,000 BTU/h ÷ 15 SEER = 400 watts (or 0.4 kilowatts)
To calculate the cost of electricity when using the A/C, multiply the average kilowatts from the formula above by your local electricity rate in kilowatts per hour (kWh). For instance, 0.4 kW x $0.25 kWh = $0.10 per hour. The EnergyGuide label on the HVAC unit will also indicate the amount of energy the equipment consumes.
History of SEER Ratings
Universal standards of measurement to rate the efficiency of HVAC equipment did not exist until recently. In 1992, the government established minimum standards for air conditioning units manufactured in the U.S. In the early 1990s, it was common for HVAC equipment to have SEER ratings of around 8 or 9. The Energy Policy Act of 2005 updated the minimum standard to 13 SEER. Each state, however, has the right to set its own minimum standard, as it is not below 13 SEER.
While today’s minimum ratings of 13 or 14 SEER might seem low, they are superior in regards to efficiency when compared to units with an 8 or 9 SEER. Therefore, if you want to replace a 20-year-old air conditioner with a new one that has the minimum SEER rating, there’s a good chance that your energy efficiency will improve instantly.
How SEER Ratings Affect Your A/C Unit
Before an A/C installation, keep in mind that a SEER rating indicates the unit’s maximum potential. This means that when a unit states that it has a value of 21 SEER, for example, the rating can be as high as 21 SEER. It will not always perform at 21 SEER because the laws of thermodynamics limit the rating. Various factors affect an air conditioner’s efficiency and performance, including sun exposure, outdoor temperatures, thermostat settings, building envelope and mechanical problems.
SEER ratings are variable, which means that HVAC units with the highest SEER values may not save you money in the future or “pay for themselves.” If equipment rated at 21 SEER performs at an average of 15 SEER, it may be wiser to save money and purchase an A/C with a lower SEER rating. An HVAC specialist can help you determine the most appropriate SEER rating for your new A/C unit using special equations that average the maximum Energy Efficiency Raito (EER) over the range of expected seasonal temperatures. In general, good SEER values for residential air conditioners are 14 to 16.
Other Factors to Consider in an A/C Unit
While SEER ratings are an important factor when buying an air conditioner, it is also necessary to consider:
- Your budget
- The size of your home
- The size of the air conditioning unit and its air handling capacity; a specialist will tell you the exact size you need
- Your area’s climate
- The length of the cooling season
- The amount of time you spend at home
- The number of hours you plan to use the A/C per day
- The indoor temperatures that you prefer
- EER ratings
- Quiet operations
- The presence of fan-only switches, which would allow you to circulate air in your home without conditioning it
- Automatic-delay fan switch that turns off the fan shortly after the compressor turns off
- Ease of maintenance
- Lifetime costs, including energy, maintenance and repairs
- A unit’s quality and life expectancy
- The manufacturer’s history of reliability
- Warranty terms
The implementation of SEER ratings have made air conditioners more energy efficient and Earth-friendly, creating a win-win situation for all. When planning a new A/C installation, get in touch with the specialists at AAA Heating and Cooling to learn more about the options available and receive expert help with determining the best SEER rating for your comfort and energy savings goals.