What Is a Good SEER Rating for an Air Conditioner?

If you are only going for a new installation, you should choose an air conditioner with at least a 14 SEER rating. Until recently, the SEER rating of 13 was considered a minimum, but the air cons developed and became more efficient in time, so the standard is now 14.

This means that it is more efficient than the old air cons that used to have SEER ratings of 10 and below.

Your SEER rating is not the only thing you must consider when choosing your next air conditioning system. It needs to be observed together with the thermal rating of your home. This is calculated based on your home insulation, orientation and other factors. It is what we call NaTHERS rating:

Your home can be rated anywhere from 0 to 10 stars. Combined with your high SEER rating air conditioner, you will have one energy-efficient household with pleasant air temperature throughout the year.

What is SEER and EER Rating?

You may have noticed that there are the SEER and the EER ratings. The EER rating is the energy efficiency ratio. The SEER rating is the seasoned energy efficiency ratio. EER is calculated based on a steady outside temperature, while the SEER is calculated for a certain temperature range.

EER shows the ratio between the cooling achieved and the energy consumed. This calculation is done for standard climate conditions: outside temperature and humidity. This rating has sound logic, but it is not entirely precise. That’s why we need the SEER.

SEER is the ratio of energy spent to cool a home and the achieved cooling results during the cooling season. The outside temperature, humidity and other factors significantly influence an air con's cooling ability. That’s why these conditions are taken into account to provide more precision.

How Is SEER Measured?

You don’t have to measure SEER. That is something the manufacturers do. The manufacturer puts it on your air-con label. SEER is measured based on the Australian climate zones because the cooling seasons in different zones are not the same.

You just need to read the labels, but if you really want to know the details about how the manufacturers come up with that number, you can always read up on the VIPAC SEER calculator, especially if you don’t mind getting too technical.

What Does 14 SEER Air Conditioner Rating Mean?

So, you have read your air conditioner label, and it says SEER 14. What does that mean? Your SEER rating shows how much cooling you will get compared to how much electricity you will spend. This is the calculation for an average SEER 14 split system air conditioner.

Let’s take a 5 kW air conditioner into account. For the sake of calculations, we will guess that this type of device works 8 hours daily for 125 cooling days a year.

1. Convert kW to BTU. When we convert the 5 kW into the BTU rating, we will get 18,000 BTU. We need that number to calculate our SEER performance.
   

   kW Units	BTU units
   2.5 kW	9, 000 BTU
   3.2 – 3.5 kW	12, 000 BTU
   5 kW	18, 000 BTU
   7 – 7.4 kW	24, 000 BTU
   8.4 kW	30, 000 BTU

2. Calculate the number of cooling hours per season. We said we consider 8 hours a day per 125 days for a cooling season. In our case, this is 1,000 hours per cooling season.
3. Calculate the electricity usage per cooling season. This means multiplying the number of cooling hours with your air con BTU. In our case that’s 18, 000 BTU x 1,000 per year = 18, 000, 000 of BTU/year
4. Factor in your SEER rating. Divide your electricity usage per cooling season with your SEER rating. That is 18 000 000 BTU/ year divided by 14. That is 1,285,714 W, which is roughly 1,286 kWh per year.

This can be shortened by multiplying your BTU with the SEER rating and dividing by 1000 to get your hourly kW spending. In our case, 18 000/14 = 1,285.7 W = 1.28 kW per hour.

When you have that number, multiply it with the expected number of cooling hours in a season.

Is a Higher or Lower SEER Rating Better?

A higher SEER rating is better than a lower SEER rating. It means that SEER 16 is more efficient than SEER 14 and will use less electricity to work in the same amount of time. Now that we know how to calculate the effects of your SEER rating, we can turn these differences into actual electricity bill costs.

For the sake of calculation, let’s say we use devices that work the same number of hours during one season and have the same capacity of 5 kW or 18 000 BTU. Also, let’s say those same devices are SEER 10, SEER 14 and SEER 16. We calculate that the air con works 1000 hours per season, and the average electricity price is $0.26 per kWh.

Notice that there are many variables in this calculation. You may have a 6 kW device or keep your air-con running for 10 hours daily. In some climates, the cooling season lasts 90 days; in others, it lasts 250. That is why these numbers may vary a lot, but you now have the tools to calculate them.

Now that you know your running costs, you need to add to that the costs of your air conditioner and the costs of installation.

Ask for several quotes for your air conditioning installation from Service Seeking professionals. That way, you can reduce your air conditioning costs in the best possible way.