Experiments on influences of volcano ashfall on building air conditioning equipment are performed. In the experiments, cumulative ashfall depths that can affect the operations of an exterior unit and a cooling tower are mainly concerned because they are placed outdoor and are exposed to ashfall directly at the time of volcano eruption. Through the experiments, cumulative ashfall depths are found to be 10-20mm and 20-30mm for the external unit and the cooling tower respectively, when their operations begin to be recognized deviated from their normal performances.
