Ductless mini-split units are a viable alternative to ducted HVAC systems, offering superior energy efficiency and a simpler installation.
Many mini-splits also have a reversible design, which means they can operate as air conditioners during summer and as heat pumps during winter. This means you’re combining two mechanical systems into one, saving on both equipment purchases and installation costs.
As you might imagine from their name, mini-splits are composed of an indoor unit and an outdoor unit, which are connected by insulated refrigerant lines.
Mini-splits are called “ductless” because they don’t need air ducts like traditional HVAC installations, and “split” because they are divided into an indoor and outdoor unit.
The indoor unit circulates air from the room where you install it, lowering or raising its temperature according to the thermostat settings.
Here we will discuss the main advantages of mini-split units when compared with traditional window-type air conditioners and ducted systems. We will also review some of the best mini-split brands available in now for the upcoming year.
Pro Tip: Before upgrading your space heating or air conditioning system, make sure your home is properly insulated and seal any air leaks. This will reduce the workload on the new HVAC equipment, and you will achieve even greater energy savings.
Understanding Energy Efficiency Metrics for Mini-Split Units
When purchasing any type of equipment, having a numerical value that describes energy efficiency is very useful.
For example, we look at the gas mileage value (MPG) when comparing different types of cars, to get an idea of their fuel consumption. In the case of mini-split units, there are two energy efficiency metrics we need to consider.
- The Seasonal Energy Efficiency Ratio or SEER describes the efficiency of a mini-split air conditioner.
- The Heating Seasonal Performance Factor of HSPF describes the efficiency of a mini-split heat pump.
A reversible mini-split capable of operating as either an air conditioner or a heat pump will have both metrics, a SEER for cooling mode and an HSPF for heating mode.
In both cases, a higher efficiency rating translates into less power consumption and lower electricity bills. Understanding these metrics is important before comparing mini-splits from different manufacturers.
The SEER can be defined as the average cooling output per unit of electricity consumed, during the season when air conditioning is typically used.
The cooling output is measured in British Thermal Units (BTU), while the electricity input is measured in watt-hours. This means you can estimate power consumption by dividing the rated cooling output (BTU/hour) by the SEER value.
- As a quick example, consider a mini-split air conditioner with a rated cooling capacity of 12,000 BTU/hour and SEER 24 efficiency.
- Dividing both values, you get an average power consumption of 500 W or 0.5 kW.
Assuming you use this air conditioner for 2,000 hours in a year, you can expect an electricity consumption of around 1,000 kWh. At an electricity tariff of 16 cents/kWh, this adds $160 to your annual power bills.
You should look for the highest possible SEER rating, regardless of the mini-split brand since high efficiency can save you hundreds of dollars in cooling over time.
If you repeat the calculation with the same cooling capacity (12,000 BTU/h) but a lower SEER rating of 13, the annual cooling cost increases to nearly $300.
The HSPF used by heat pumps is a similar concept: the average heating output per unit of electricity consumed. In the case of reversible mini-split units, you will notice that the HSPF for heat pump mode is typically lower than the SEER for air conditioning mode.
While the most efficient mini-split air conditioners reach a SEER of over 30, the most efficient mini-split heat pumps offer an HSPF of around 13-14. This happens because cold weather limits the efficiency of the refrigeration compression cycle used by mini-splits.