A COP (Coefficient of Performance) of 7 indicates that for every 1 kW of electricity consumed, the unit produces 7 kW of heat. To achieve this, buyers should look for EVI (Enhanced Vapor Injection) technology and DC Inverter compressors (such as Panasonic or Mitsubishi). Ensure the unit utilizes R32 or R290 eco-friendly refrigerants, which offer higher thermal conductivity. Additionally, the heat exchanger should be made of titanium or high-grade stainless steel to prevent corrosion and maximize heat transfer efficiency.