You can also check out our reviews of the leading portable air conditioners. In this post, we tell you exactly what their EER ratings are.
Air con units come attached with different energy-efficient ratings that allow you to know how many BTUs per hour are consumed for each watt of power they draw. For instance, the ratings for room conditioners are measured in terms of Energy Efficient Ratio or EER.
On the other hand, central air conditioners ratings are taken in terms of the Seasonal Energy Efficiency Ratio or SEER. These ratings can be seen as the Energy Guide label on all new units.
How do I measure EER?
EER is the British Thermal Unit (BTU) rating over its wattage. For instance, if one unit having a 10,000 BTU consumes 1,200 watts, its EER can be calculated as (10,000 BTU/1,200 watts) = 8.3 EER. An air con with greater EER would be considered more efficient as against a lower EER value. However, a higher EER air con comes attached with a higher price tag.
Is it worth it to invest in a portable unit with higher EER ratings?
Let’s compare air conditioners with two different EER ratings — one 10,000 BTU air con unit with 8.3 EER consuming 1,200 watts; the other 10,000 BTU unit with 10 EER consuming 1,000 watts. Now consider that the price difference between the two air conditioners is $100. To find which one is an expensive unit, you need to know two basic things as mentioned below:
1. The operational time in hours per year
2. The rate of a kilowatt-hour (kWh) in your area
Let’s consider that you will be using a model in the summer (about 5 months a year) and the average operational time would be 8 hours a day. If the cost of a kilowatt-hour in your area is $0.10 — the difference in energy consumption between the two units will be two hundred watts. This simply means that every five hours the less expensive unit will use one extra kWh as compared to the more expensive unit.
Let’s say that there are 30 days in a month and you are operating the air conditioner during the summer months.
5 months x 30 days/month x 8 hr/day = 1200 hours
[(1200 hrs x 200 watts) / (1000 watts/kW)] x $0.10/kWh = $24.00
The price difference between the two is approximately $100. The above calculation demonstrates that it will take about 4 years for the more expensive air conditioner unit to break even.
A note for buyers:
You cannot trust all BTU ratings. Some manufacturers overstate when it comes to BTU units in order to sell their products. So, it is important not to consider just EER ratings while buying an air conditioner. Do a comprehensive research while buying a particular unit and get the best deal for the same.