At least two sensors are required to control the roof fan: one outside and one in the structures (target area). The control unit adjusts the roof fan using the data from the two sensors, and the mobile base station then uploads the data directly to the cloud. Several sensors can be installed in the ventilated area if data is to be collected more widely or more accurately. If the ventilated area has more than one sensor, any one of them can be selected to feed the control unit. Additionally, more control units can be installed with sensors linked to them – for example, on other buildings nearby – and connected to the same mobile base station.