HVAC tonnage is a measure of the cooling capacity of a heating, ventilation, and air conditioning (HVAC) system. It is usually expressed in British Thermal Units (BTUs) per hour or in tons. One ton of cooling capacity is equal to 12,000 BTUs per hour. The tonnage of an HVAC system is determined by the amount of heat it can remove from a space in an hour. The higher the tonnage, the more cooling capacity the system has. The tonnage of an HVAC system is determined by the size of the space it is cooling, the amount of insulation in the space, the number of windows, and the climate of the area. The tonnage of an HVAC system is important to consider when purchasing a new system, as it will determine the size and type of system needed to adequately cool the space. Additionally, an HVAC system with too much tonnage can be inefficient and expensive to operate.