Powerful greenhouse heater , compact, energy-efficient High ventilation rate up to 460 m³/h. The fan setting. By using the fan setting, all the air in the greenhouse can be circulated even in the summer season. With the window open and the fan on, the greenhouse can be cooled down. Air circulation in the summer is also necessary for the pollination of many flowers and vegetables. Bio Green is a family owned manufacturer for greenhouse heaters since 1984 with a lot of expertise and expirience in the greenhouse heating field.