In the United States, how is the cooling capacity of air-conditioning equipment expressed?

The cooling capacity of air-conditioning equipment in the United States is commonly expressed in tons. One ton of cooling capacity is equivalent to the ability to remove 12,000 British Thermal Units (BTUs) of heat per hour. This unit of measure originated from the amount of heat absorbed by a ton of ice melting over a 24-hour period. Using tons as a measurement allows for a more intuitive understanding of air conditioner's cooling power in a residential or commercial setting.

While BTUs are also used and important in the industry, the standard expression in tons provides a clearer benchmark for evaluating larger systems where cooling capacities tend to be significant. The options of Pascals and gallons are not relevant in the context of cooling capacity, as Pascals measure pressure and gallons measure volume rather than thermal energy or cooling effectiveness.