Air conditioning capacity， or cooling capacity， is measured in British thermal units per hour (BTU/h) or in tons. One ton of air conditioning capacity equals 12，000 BTUs per hour.

The BTU measurement is used to determine how much cooling a particular room or space requires， taking into consideration the size of the room， number of occupants， sunlight exposure， and the room’s insulation. The larger the space and number of occupants， the more BTUs are required.

For example， a room that is 200 square feet， with no direct sunlight exposure， and has good insulation， would require approximately 6，000 BTUs of cooling capacity. However， a room that is 500 square feet， with direct sunlight exposure， and poor insulation， would require approximately 14，000 BTUs of cooling capacity.

When purchasing an air conditioning unit， it is important to consider the cooling capacity needed for the intended space. An undersized unit will not cool the space sufficiently， while an oversized unit will not only be more expensive， but will also lead to excess humidity and moisture problems.

In summary， the air conditioning capacity， or cooling capacity， is measured in BTUs or tons， and depends on the size of the room， number of occupants， sunlight exposure， and insulation. It is important to choose the right size unit to ensure sufficient cooling and avoid excess costs and humidity problems.