Ensuring your home stays cool during the long, hot summer is obviously important, and there are numerous options that can help keep your home cool. Both central air conditioners and ductless mini-split ACs can be a great choice depending on your building and your specific goals. Still, with steadily rising electricity prices, you obviously want to know that whatever option you choose is energy efficient and won’t cost you a fortune to run. To make this easier, we’ve produced this guide to tell you everything you need to know about the energy efficiency of both central ACs and ductless mini-splits.
An Introduction to Mini-Split Air Conditioners
Before we get into energy efficiency, it’s first important to take a closer look at what ductless mini-split ACs are since most people are unfamiliar with them. A mini-split works exactly like a central air conditioner and has the same two main components. There is an AC compressor unit that sits outside, which is connected to an indoor air handler unit. The main difference between central air conditioning and a mini-split is that mini-splits don’t require ductwork to circulate air. Instead, the air handler does all of the work on its own.
Most mini-split ACs have a single air handler and are designed to cool one room or space, whereas central ACs will pump cool air into all areas of the building that are connected to the duct system. However, there are also more advanced mini-split systems that can run multiple air handlers off of the same compressor unit. Often referred to as multi-splits, these systems can potentially provide cooling for an entire building depending on its size. Most of these systems can accommodate up to four air handlers. You can also find more powerful systems that can have as many as eight or more air handlers.
One of the benefits of using a multi-split system to cool the entire home is that each air handler has its own independent control. This means that you can set each air handler to a different temperature without affecting the others. As a result, you can have far more control of your cooling system than you would with central air conditioning.
The AC compressor consumes most of the power when the system runs, but the air handlers also draw electricity. As a result, the more air handlers the system has, the more electricity it will consume.
Understanding SEER Ratings
To properly compare the energy efficiency of different AC systems, you first need to know a bit about SEER ratings. SEER stands for seasonal energy efficiency ratio, and this is the system used to measure the energy efficiency of central ACs, heat pumps, and ductless mini-split ACs.
Unlike furnaces where the energy efficiency always remains constant, the energy efficiency of air conditioners can fluctuate depending on how hot and how humid it is outside. The SEER system was developed to overcome this problem and enable consumers to estimate approximately how much energy an air conditioner will use in total throughout one cooling season.
To calculate SEER, you need to know two things—how many BTUs (British Thermal Units) of cooling the AC produces and how many watt-hours of electricity it consumes. SEER is calculated by dividing the unit’s BTUs by the number of watt-hours the unit uses. The higher this ratio is, the more energy efficient the unit is.
The average US home runs its air conditioner for a total of 1,000 hours in a single cooling season, and you can use this number to estimate how many kilowatt-hours an air conditioner will use in one season. This can be extremely helpful since your electricity provider charges by the kilowatt hour.
Comparing the Energy Efficiency of Mini-Splits and Central ACs
Mini-splits are generally quite a bit more energy efficient than central air conditioners, and this is evidenced by their superior SEER ratings. Most central AC units range from 14 to 22 SEER, but you can find units that are as high as 28 SEER. On the other hand, even the most basic mini-split will usually be at least 20 SEER, and many units are well above 30 SEER.
The EPA estimates that a mini-split is, on average, anywhere from 20 to 30% more efficient than a central AC system. Part of this is due to the superior SEER ratings, but it is also because mini-splits don’t require ductwork. Even if the ductwork isn’t leaking, some energy will always be wasted due to heat loss and heat gain. Leaky ductwork can increase this problem by allowing much of the air to escape. This reduces the effectiveness of the system and means it will need to run for longer to cool the building to the desired temperature.
When comparing energy efficiency, it is important to look beyond SEER ratings. You also need to consider how many hours a day the system runs as this will determine how much total energy it uses. The main issue with mini-splits is that most of them are not controlled by a thermostat like central air conditioning is. A mini-split does have an internal thermostat, but its purpose is only to regulate the temperature of the air coming out of the unit.
Whereas a central AC system will automatically shut off when it reaches the set temperature, most mini-splits usually need to be manually turned on and off at the air handler using its remote control. This can be an issue if you’re attempting to keep your home cool while you’re at work. In this situation, your only option is to either turn the unit on in the morning and let it run all day or leave the unit off and come home to a hot house.
Even if you have an extremely efficient mini-split, leaving it on all day will most likely use more energy than leaving a central AC system switched on all day. The central AC won’t run constantly if it’s working properly, but the mini-split will unless you are home to turn it on and off as needed.
There are smart mini-splits that allow you to overcome this problem. These systems are connected to a smart thermostat that you can control remotely from your phone. The thermostat also monitors the temperature and will automatically turn the mini-split on and off just like a central AC’s thermostat will.
If you already have a mini-split system, you may be able to upgrade it to a smart system. If you already have a smart thermostat, you can install a Wi-Fi controller onto the mini-split. You can also install a smart thermostat that controls the unit. If you choose to go this route, keep in mind you will need a separate thermostat for each air handler.
Expert AC Services and Support
If you have any questions about mini-splits or central ACs, the knowledgeable HVAC experts at Woodward Heating Air Plumbing in Salem have the answers. We install both types of systems, and we can help you choose which is best for your home. Our technicians can also repair and maintain all types of heating and cooling equipment from any manufacturer.
Don’t suffer through another sweltering summer without adequate air conditioning. Instead, give Woodward Heating Air Plumbing a call to enjoy the cool comfort of a new mini-split or central AC.
