Ductless mini-splits provide a high-efficiency alternative to conventional window- or wall-type HVAC equipment. In addition to offering energy efficiency, ductless mini-splits can be installed with minimal modifications to indoor spaces. They can be especially useful in robust construction, such as pre-war apartment buildings where installing ducted HVAC systems is especially challenging.
Based on their function, ductless mini-splits can be classified into two main types: air conditioners and heat pumps. Although AC units are exclusively for space cooling, heat pumps offer reversible operation and can also provide heating during the winter. In heating mode, heat pumps typically consume less than 50% of the electricity required by resistance heaters, or even less than 25% if you opt for a higher-tier unit.
More efficient heat pumps can match the operating cost of gas space heating, but with zero emissions if the electrical energy comes from a clean source.
Mini-Split System Settings
Mini-splits can also be classified based on their physical construction. Both air conditioners and heat pumps are available in the system configurations described below:
|
MINI-SPLIT SETUP |
DESCRIPTION |
|
1) Floor mounted |
Suitable for locations where the upper wall area is limited. A floor-mounted mini-split can easily fit under a window. |
|
2) Thin duct |
Similar in appearance to central AC units, uses minimal ductwork and can be installed in a ceiling or overhead cabinet. |
|
3) Compact cassette |
A very compact type of mini-split, which uses intelligent fans to save energy and evenly distribute air. |
|
4) Wall mounted |
The traditional setup, mounted on top of a wall and connected to the external condenser. Refrigerant line length can be minimized by installing the condensing unit on the other side of the wall. |
Ductless mini-split air conditioning
The efficiency of a ductless mini-split AC is typically described with a performance metric called the Seasonal Energy Efficiency Ratio (SEER). SEER is a ratio of cooling output (BTU) to electricity input (watt-hours) during a typical cooling season and can be compared to the fuel economy figure of a car: just like a 50-liter car. MPG uses half the fuel. Like a 25 MPG car, a SEER 20 AC unit consumes half the power needed by a SEER 10 unit.
Alternatively, you may find cooling efficiency stated as an Energy Efficiency Ratio (EER), which is for specific test conditions rather than the entire cooling season. Some units also display a Coefficient of Performance (COP), which is a ratio of cooling output to power input, both quantities expressed in watts.
Ductless mini-split heat pumps
As stated previously, heat pumps can operate in both heating and cooling mode. When in cooling mode, they are basically air conditioners and their efficiency is described as a SEER value. Conversely, when operating in heating mode, the performance metric is the Heating Seasonal Performance Factor (HSPF), a relationship between heating output (BTU) and electricity input (watt-hours) for a station. typical heating.
Note that a heat pump has separate SEER and HSPF values. SEER is typically higher since heat pumps are less efficient in winter. However, they are still much more efficient than an electric resistance heater:
- A resistance heater provides one kWh of heat for every kWh of electricity consumed.
- Heat pumps provide 2 to 4 kWh of heat for every kWh of electricity, depending on their efficiency.
Incentives for Ductless Mini Splits in New York and NJ
Con Edison manages an incentive program for energy efficiency and renewable generation measures in New York, and ductless mini-splits are covered.
- The rebate for residential consumers is $300 per unit, increasing to $600 per unit in select neighborhoods in Queens and Brooklyn. An additional $135 discount is available if you add an approved smart thermostat ($185 in the Neighborhood Program).
- The rebate for commercial energy consumers is $200/ton in the neighborhoods of Queens and Brooklyn covered by the program.
In the case of New Jersey, incentives are managed through the NJ Clean Energy Program.
- The COOLAdvantage subprogram provides incentives for existing residential construction. The discount for mini-split air conditioners and heat pumps is $500 per unit.
- The SmartStart Buildings subprogram applies to multifamily and commercial buildings. The discount is determined from tables, based on the capacity and efficiency of the equipment.
Find the best HVAC upgrades for your building.
Final Recommendations
HVAC upgrades can provide an excellent return on investment, especially if your building's equipment is very old. For example, window-type and wall-type units are not only inefficient; they also create a gap in the building envelope, increasing heating and cooling loads.
