People call us at Bel-Aire Heating & Cooling in Grand Rapids, Portage, and Three Rivers and ask if mini-splits are more efficient than a central air conditioning system. The answer is that it depends upon your home and your individual use case. Where they are best suited, mini-splits are usually more energy efficient than central air.
How Are Mini-Splits Different From Central Air?
Central air has an outside unit and an inside unit that is usually tucked away in a basement or other hidden area of a home. It uses ducts to transport the cool air to different areas in your home. Often, people leave their attic, garage, and basement without ducts and vents.
A mini-split has an outdoor unit and one or more indoor units. Mini-splits don’t have ducts. This is why they are also called “ductless air conditioning systems.” These ductless units only have a line that carries refrigerant, a drainage line, and an electrical line running to the indoor units. The indoor units, called “heads,” each have a blower fan, evaporator coils, and an air filter. The fan blows the warm air from your room over the coils filled with refrigerant to create a cooling effect. You only need three-inch holes to get these lines through walls, floors, and ceilings.
Mini-splits have some features that make them very energy efficient. One reason for their efficiency is their variable-speed compressors. Most people have central air conditioning units with compressors that are single-speed. Mini-splits, with their variable-speed compressors, can run more efficiently at only the speed needed to keep your room at the desired temperature. This saves energy and eliminates larger changes in the general room temperature. You can buy central air units with multi-speed and variable-speed compressors, though.
Another energy-saving feature found in mini-splits and not in central air conditioning systems is inverters. The inverters in a mini-split convert the alternating current, AC, in your home wiring system to DC, direct current. This saves you energy.
The lack of ductwork is another plus in terms of energy savings. According to the Department of Energy, losses of cool air through ducts in central air systems can add up to as much as 30% of the energy the system consumes. This is especially true if ducts are in a space of the house where the air is not cooled, like your attic or basement.
Also, energy is saved by mini-splits because you can turn down or turn off indoor units in unused rooms. In most central air units, you can only close off vents in unused rooms. When you close vents in a central air unit, unless the unit is equipped with a multi-speed compressor and fan, you are still using the same amount of energy as you did before you closed the vents.
Usage Cases for Mini-Splits
Some people with central air conditioning add a single-head mini-split to provide cooling for a garage or basement that is not supplied by their ductwork. When they are not using that area of their home, they can just turn the mini-split off, saving energy. Other common places to install a mini-split include new additions to the house and granny shacks. Supplying air conditioning for a smaller home is a great usage case for mini-splits, as is cooling a home with smaller rooms. Also, mini-splits are often great where you cannot install ductwork in a cost-effective manner. Some older homes are difficult and/or expensive to retrofit with ducts.
Drawbacks of Mini-Splits
Mini-splits are not energy efficient in supplying conditioned air to homes with open floor plans or larger rooms. You would need multiple indoor units in larger rooms. Each head unit has a limit to the cooling BTUs they can produce.
Mini-splits are also not cost-effective in terms of initial outlay when you need many indoor units. There is a finite number of heads an outdoor unit can accommodate, so some homes would even require two outdoor units. In fact, if you already have ductwork, replacing a central air conditioning unit with another is often around 30% cheaper than installing a mini-split.
There are a few other types of drawbacks of mini-splits in comparison to central air conditioning systems. Mini-splits have far less robust filtration options. Their filters are flimsy, and the units are just recycling indoor air. Central air conditioning units have large, thick, robust filters out of the box. They can easily be modified to create even greater filtration and improve indoor air quality for families that suffer from allergies, for example.
Also, if you need to add a condensate pump to a mini-split system, it will add to the initial cost of the system and to the energy cost of running the system. It will also add noise. Condensate pumps are necessary when the system cannot drain the condensation downhill to get it outside.
Central Air Efficiency and Usage Cases
Central air conditioning systems that most people purchase are in the range of 14 to 15 SEER. As you have seen, though, mini-splits are not as energy efficient as central air if the heads are located in rooms that are too large for one head to cool the entire space.
Also, central air is often a less costly and more energy-efficient alternative for a family with a larger home that needs to keep all of the rooms cooled.
You can purchase central air conditioning systems that have two-stage or multi-stage compressors that will bump up your SEER rating to 20 and over. Since mini-splits with many heads are 30% more expensive to install in a home that already has ductwork, the cost may be comparable.
The bottom line is that mini-splits are not the most energy efficient way of cooling a home in every use case. In homes with smaller, well-defined rooms, a mini-split will usually be more energy efficient and save you money each month on your electric bill. Some combination of central air and mini-splits may be the best for some use cases in larger homes or ones with more open floor plans. There are also other use cases where customers have floor-to-ceiling windows or more window coverage than average that are usually better served with central air, but each home needs an expert evaluation to help the customer find the best cooling system solution for their home and budget.
An HVAC Company You Can Trust
Here at Bel-Aire Heating & Cooling, we have offices in Grand Rapids, Portage, and Three Rivers, MI, and we have served our local community’s heating and cooling needs for the past 61 years. We provide installations, maintenance, and repair for all types of heating and cooling systems. If you need an emergency repair, we provide 24/7 service. We also provide a full range of indoor air quality products and services.
Our team provides free estimates, monthly specials, and financing on approved credit on installations. We actually fill out the forms for you so that you will get your energy-savings rebates. We have a BBB A+ rating and are a Lennox Premier Dealer.
Call us today at Bel-Aire Heating & Cooling in Grand Rapids, Portage, or Three Rivers. We will come out and give you an estimate for an air conditioning installation.