Generally ​​20–30 BTU per square foot​​ (a 200 sq.ft. room needs ​​4000–6000 BTU). Adjust for factors like direct sunlight (add 10% for west/south-facing rooms) or high ceilings (add 15% if over 8 ft.). Avoid undersized units (constant running = higher bills) or oversized ones (energy waste + uneven cooling).

Aim for ​​SEER ≥16​​ and ​​EER ≥11​​ (higher in hot climates). You will embrace a greener lifestyle with high SEER2 rated AC unit. Better to look for ENERGY STAR-certified models with minimal environmental impact and tax credits (up to ​​$3,000​​).

Humidity Control​​: Choose models with ​​≥30 pints/day dehumidification​​ (ideal for humid areas like Florida). Smart Control​​: Alexa/Google Home compatibility for remote adjustments. Zoning​​: Multi-stage systems for large homes to set different temperatures per room.

Indoor units: ≤48 dB (like a whisper). Outdoor units: ≤58 dB (quieter than a vacuum). Those air conditioners with inverter technology usually run softly. Opt for sleep modes and install outdoor units away from bedrooms. Use soundproof kits if needed.