What unit is commonly used to express the effectiveness of air conditioning systems?

The effectiveness of air conditioning systems is commonly expressed in BTU per hour (Btu/h). This unit measures the cooling or heating capacity of the system, indicating how many British Thermal Units the air conditioning unit can transfer in one hour. It's a crucial metric because it helps determine whether a system is suitable for the specific cooling load requirements of a space. Understanding this measurement allows HVAC professionals to choose the right system for effective temperature control and energy efficiency.

Other options represent different metrics. CFM, which stands for cubic feet per minute, measures airflow rate but does not directly reflect the cooling or heating ability of the system itself. LPM, or liters per minute, is typically used for measuring fluid flow rates and is not applicable in the context of assessing air conditioning effectiveness. HP, or horsepower, relates to the power output of the compressor or motor in the AC system but doesn't provide a direct measure of cooling effectiveness. Therefore, BTU/h is the most relevant unit for evaluating air conditioning performance.