SEER or EER – Does it Matter When Replacing Your AC?

Ensure Your AC Replacement is Energy Efficient

As the New Year begins, you might be considering installing a new AC unit – after all, there’s nothing like being surrounded by cool air to give you that ‘fresh start’ feeling! An AC replacement also provides the perfect opportunity for you to ensure that your next AC unit is as energy efficient as possible. Although the world of energy efficiency ratings can be confusing for someone who isn’t in the industry, it’s important to get to grips with these rating systems and their implications if you’re serious about saving energy with your AC replacement.

Energy efficiency is important
To some, ‘energy efficiency’ is just a fashionable word used by marketers and product developers. But in reality, whether or not your AC unit is energy efficient can make a significant difference to your utility bill. Especially in Florida, where cooling units are in use most of the year, having a more efficient system can save you hundreds of dollars. Another factor to consider is the environment. By upgrading to a more energy efficient AC, you will be reducing your electricity consumption. This means that you will be contributing less to the burning of fossil fuels, and will lower your carbon footprint.

What are EER and SEER ratings?
The energy efficiency of an AC unit measures how effectively it cools down a given area, against the amount of power it has consumed in order to do so. There are two key rating systems which measure this: the EER and SEER systems. EER stands for ‘Energy Efficiency Ratio’, and is generally used for room AC units. SEER stands for ‘Seasonal Energy Efficiency Ratio’, and tends to be used for central AC units. Both rating systems measure the cooling capacity of the AC unit (measured in British thermal units – Btu) in relation to the electrical energy consumed (measured in watts per hour). However, what makes the rating systems different is that they measure energy efficiency under different conditions – SEER measures energy efficiency over one whole cooling season, with varying temperatures, whereas EER measures energy efficiency for stable operating conditions.

How are EER and SEER ratings determined?
EER ratings are calculated using standardized conditions set out by the Air-Conditioning, Heating and Refrigeration Institute (ARHI). The efficiency of the AC is measured using an outdoor temperature of 95°F and inside temperature of 80°F, at 50% humidity. SEER ratings are calculated over varying conditions, using a range of outdoor temperatures (65°F-104°F), and differing levels of indoor humidity. In both rating systems, a higher rating means greater energy efficiency. Since 2015, the Department of Energy has required all AC units in Florida to have minimum SEER rating of 14 – so be sure your AC replacement unit meets this standard.

Comparing EER and SEER
While the U.S. government only requires that SEER ratings be displayed on AC units, many units display EER ratings, too. Generally, EER will indicate the efficiency of an AC in the peak of summer, as it is measured only at one high temperature. SEER, on the other hand, is an average, so it is better for measuring efficiency across the season, but is not as well adapted to predicting efficiency for the hottest summer months in Southern homes. For this reason, EER tends to be more accurate for climates in which the average temperature during AC use is close to or above 95°F. If you’re intending to install a new AC and want expert advice on the matter, then it’s best to consult an AC replacement contractor to find out more about the rating which will best suit your particular household and climate.