SEER (Seasonal Energy Efficiency Ratio) measures a system’s cooling output over a season divided by the electricity input—so a higher SEER means better efficiency. For example, modern ductless mini-splits can have SEER ratings from the mid-20s up to nearly 40, translating into significant energy savings and reduced environmental impact.

High SEER ratings are often tied to compact wall-mounted units. When you switch to ducted or ceiling cassette variants, efficiency typically declines into the low 20s—similar to traditional HVAC systems.

Wall-mounted mini-splits typically include only small, basic filters designed to protect the indoor unit—not to significantly clean indoor air. For robust filtration, it's best to supplement with standalone air purifiers or incorporate HRV/ERV systems for ventilation and air quality.