Your heating and air conditioning contractor will probably use the SEER acronym when he’s stressing that your air conditioning system should be of highest efficiency possible.

What does SEER mean? Let’s see what we find on Wikipedia:

The efficiency of air conditioners is often rated by the Seasonal Energy Efficiency Ratio (SEER) which is defined by the Air Conditioning, Heating and Refrigeration Institute in its standard ARI 210/240, Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump Equipment.

The SEER rating of an ac unit is the cooling output during a typical cooling-season divided by the total electric energy input during the same period. The higher the unit’s SEER rating the more energy efficient it is. In the U.S., the SEER is the ratio of cooling in British thermal unit (BTU) to the energy consumed in watt-hours. The connection to the Coefficient of Performance (COP), a more universal dimensionless measure of efficiency, is discussed in the following section.

Now let’s find out what typical SEER specs can be found in ac units today. On the Trane and Carrier website we find specification for split ac units between 13 and 21 SEER. These ratios depend on model (and price) and are specified using the prefix ‘up to’. This mean depending on locale and seasonal conditions, maintenance state and other factors the SEER can be lower. And we have to realize that older systems were not built with today’s technology and provide a much lower SEER.

To put the above in perspective we need to know that since 2006 new ac systems must have at least an SEER of 13. Window units are exempt from this requirement. And to be Energy Star qualified, an SEER of 14 needs to be achieved. This also means that for systems over 10 years old SEER values lower than 9 can be expected, again very much depending on maintenance condition such as cleanliness of the coils (heat exchangers) or pressure of the refrigerant and so on.

Now an example and I’m quoting again Wikipedia:

Consider a 5,000-British-thermal-unit-per-hour (1,500 W) air-conditioning unit, with a SEER of 10 BTU/Wh, operating for a total of 1000 hours during an annual cooling season (e.g., 8 hours per day for 125 days).

The annual total cooling output would be:
5000 BTU/h × 8 h/day × 125 days/year = 5,000,000 BTU/year

With a SEER of 10 BTU/W·h, the annual electrical energy usage would be about:
5,000,000 BTU/year / 10 BTU/W·h = 500,000 W·h/year

The average power usage may also be calculated more simply by:
Average power = (BTU/h) / (SEER) = 5000 / 10 = 500 W

If your electricity cost is 20¢/kW·h, then your cost per operating hour is:
0.5 kW * 20¢/kW·h = 10¢/h

So, using above example means that investing in a new top rated system with an SEER of 20 will save 50% of the cooling cost of an SEER 10 system. This will increase to 75% of the energy cost in case your current system is over 10 years old and we assume an SEER of 5 for such an old system. Your heating and air consultant can estimate the SEER of your current system. Or you can do the calculation or better estimation yourself by reviewing your spring, summer and fall electric power bills.

Want to know more about energy efficiency and ac units? Contact your heating and air contractor or call our technicians for a detail discussion.