Clean rooms place special demands on their ventilation systems, including sufficient air flow and pressure, precise temperature and humidity control, and consistent air quality. So-called fan filter units (FFU) combine filter systems and fans and are designed for installation in ceilings. For large clean rooms in particular, such a configuration satisfies the requirements. The range of products offered by ebm-papst Mulfingen includes RadiCal centrifugal fans that are specially designed for use in fan filter units and satisfy all mandatory requirements for such applications. The fans cover an air performance range from 1,170 to 2,330 m³/h at a back pressure of up to 300 Pa. GreenTech EC technology is also of particular interest for clean room systems since FFUs equipped with it can reach efficiency levels of more than 50%, which was not previously possible with conventional technology. In addition, strict noise protection regulations apply in clean rooms. The RadiCal impellers, which were optimized according to aerodynamic criteria, ensure low noise emissions; the fans are 6-7 dB quieter than the previous market standard. For operation in accordance with user requirements, the EC fans can be controlled with an analog 0-10 V signal or via a digital RS485 interface. The latter is especially effective for clean room systems, where several thousand fan modules are often at work in the ceilings. In such cases, the networking capabilities offered by MODBUS or ebmBUS have proven very advantageous for controlling and monitoring these complex systems. Besides the production of semiconductors, clean-room conditions are also called for in production processes for optics and lasers, aerospace, medical research and treatment, and foodstuffs and pharmaceuticals. Clean-room technology prevents contamination from compromising production processes and damaging sensitive products, and there are also processes involving materials that must be kept from reaching the outside air. RadiCal fans have demonstrated their capabilities all over the world, for instance in the clean rooms where flat panel displays are produced. The market leaders from Korea and Taiwan relied on GreenTech EC technology from ebm-papst for the production of their large flat panel products.